document_title: Earth

question_text: what is the real name of the earth

question_tokens: what is the real name of the earth

text: Earth

text: Name and etymology

text: The modern English word  Earth developed from a wide variety of Middle English forms,[n 6] which derived from an Old English noun most often spelled eorðe.[40] It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō. In its earliest appearances, eorðe was already being used to translate the many senses of Latin terra and Greek γῆ (gē): the ground,[n 7] its soil,[n 8] dry land,[n 9] the human world,[n 10] the surface of the world (including the sea),[n 11] and the globe itself.[n 12] As with Terra and Gaia, Earth was a personified goddess in Germanic paganism: the Angles were listed by Tacitus as among the devotees of Nerthus,[49] and later Norse mythology included Jörð, a giantess often given as the mother of Thor.[50]

text: Originally, earth was written in lowercase, and from early Middle English, its definite sense as "the globe" was expressed as the earth. By Early Modern English, many nouns were capitalized, and the earth became (and often remained) the Earth, particularly when referenced along with other heavenly bodies. More recently, the name is sometimes simply given as Earth, by analogy with the names of the other planets.[40] House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name (e.g. "Earth's atmosphere") but writes it in lowercase when preceded by the (e.g. "the atmosphere of the earth"). It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing?"[51]

text: Chronology

text: Formation

text: The oldest material found in the Solar System is dated to 7000456720000000000♠4.5672±0.0006 billion years ago (Bya).[52] By 7000454000000000000♠4.54±0.04 Bya[53] the primordial Earth had formed. The bodies in the Solar System formed and evolved with the Sun. In theory, a solar nebula partitions a volume out of a molecular cloud by gravitational collapse, which begins to spin and flatten into a circumstellar disk, and then the planets grow out of that disk with the Sun. A nebula contains gas, ice grains, and dust (including primordial nuclides). According to nebular theory, planetesimals formed by accretion, with the primordial Earth taking 10–7001200000000000000♠20 million years (Mys) to form.[54]

text: A subject of research is the formation of the Moon, some 4.53 Bya.[55] A leading hypothesis is that it was formed by accretion from material loosed from Earth after a Mars-sized object, named Theia, hit Earth.[56] In this view, the mass of Theia was approximately 10 percent of Earth,[57] it hit Earth with a glancing blow and some of its mass merged with Earth.[58] Between approximately 4.1 and 7000380000000000000♠3.8 Bya, numerous asteroid impacts during the Late Heavy Bombardment caused significant changes to the greater surface environment of the Moon and, by inference, to that of Earth.

text: Geological history

text: Earth's atmosphere and oceans were formed by volcanic activity and outgassing. Water vapor from these sources condensed into the oceans, augmented by water and ice from asteroids, protoplanets, and comets.[59] In this model, atmospheric "greenhouse gases" kept the oceans from freezing when the newly forming Sun had only 70% of its current luminosity.[60] By 7000350000000000000♠3.5 Bya, Earth's magnetic field was established, which helped prevent the atmosphere from being stripped away by the solar wind.[61]

text: A crust formed when the molten outer layer of Earth cooled to form a solid. The two models[62] that explain land mass propose either a steady growth to the present-day forms[63] or, more likely, a rapid growth[64] early in Earth history[65] followed by a long-term steady continental area.[66][67][68] Continents formed by plate tectonics, a process ultimately driven by the continuous loss of heat from Earth's interior. Over the period of hundreds of millions of years, the supercontinents have assembled and broken apart. Roughly 7002750000000000000♠750 million years ago (Mya), one of the earliest known supercontinents, Rodinia, began to break apart. The continents later recombined to form Pannotia 7002600000000000000♠600–540 Mya, then finally Pangaea, which also broke apart 7002180000000000000♠180 Mya.[69]

text: The present pattern of ice ages began about 7001400000000000000♠40 Mya and then intensified during the Pleistocene about 7000300000000000000♠3 Mya. High-latitude regions have since undergone repeated cycles of glaciation and thaw, repeating about every 7012126230400000000♠40,000–100,000 years. The last continental glaciation ended 7011315576000000000♠10,000 years ago.[70]

text: Origin of life and evolution

text: Chemical reactions led to the first self-replicating molecules about four billion years ago. A half billion years later, the last common ancestor of all current life arose.[71] The evolution of photosynthesis allowed the Sun's energy to be harvested directly by life forms. The resultant molecular oxygen (O2) accumulated in the atmosphere and due to interaction with ultraviolet solar radiation, formed a protective ozone layer (O3) in the upper atmosphere.[72] The incorporation of smaller cells within larger ones resulted in the development of complex cells called eukaryotes.[73] True multicellular organisms formed as cells within colonies became increasingly specialized. Aided by the absorption of harmful ultraviolet radiation by the ozone layer, life colonized Earth's surface.[74] Among the earliest fossil evidence for life is microbial mat fossils found in 3.48 billion-year-old sandstone in Western Australia,[75] biogenic graphite found in 3.7 billion-year-old metasedimentary rocks in Western Greenland,[76] and remains of biotic material found in 4.1 billion-year-old rocks in Western Australia.[30][31] The earliest direct evidence of life on Earth is contained in 3.45 billion-year-old Australian rocks showing fossils of microorganisms.[77][78]

text: During the Neoproterozoic, 7002750000000000000♠750 to 580 Mya, much of Earth might have been covered in ice. This hypothesis has been termed "Snowball Earth", and it is of particular interest because it preceded the Cambrian explosion, when multicellular life forms significantly increased in complexity.[79] Following the Cambrian explosion, 7002535000000000000♠535 Mya, there have been five mass extinctions.[80] The most recent such event was 7001660000000000000♠66 Mya, when an asteroid impact triggered the extinction of the non-avian dinosaurs and other large reptiles, but spared some small animals such as mammals, which at the time resembled shrews. Mammalian life has diversified over the past 7001660000000000000♠66 Mys, and several million years ago an African ape-like animal such as Orrorin tugenensis gained the ability to stand upright.[81] This facilitated tool use and encouraged communication that provided the nutrition and stimulation needed for a larger brain, which led to the evolution of humans. The development of agriculture, and then civilization, led to humans having an influence on Earth and the nature and quantity of other life forms that continues to this day.[82]

text: Future

text: Earth's expected long-term future is tied to that of the Sun. Over the next 7000110000000000000♠1.1 Bys, solar luminosity will increase by 10%, and over the next 7000350000000000000♠3.5 Bys by 40%.[83] The Earth's increasing surface temperature will accelerate the inorganic carbon cycle, reducing CO2 concentration to levels lethally low for plants (6995099999999999999♠10 ppm for C4 photosynthesis) in approximately 7002500000000000000♠500–900 Mys.[84] The lack of vegetation will result in the loss of oxygen in the atmosphere, making animal life impossible.[85] After another billion years all surface water will have disappeared[86] and the mean global temperature will reach 70 °C (158 °F).[85] From that point, the Earth is expected to be habitable for another 7016157788000000000♠500 Ma,[84] possibly up to 7016725824800000000♠2.3 Ga if nitrogen is removed from the atmosphere.[87] Even if the Sun were eternal and stable, 27% of the water in the modern oceans will descend to the mantle in one billion years, due to reduced steam venting from mid-ocean ridges.[88]

text: The Sun will evolve to become a red giant in about 7000500000000000000♠5 Bys. Models predict that the Sun will expand to roughly 1 AU (150 million km; 93 million mi), about 250 times its present radius.[83][89] Earth's fate is less clear. As a red giant, the Sun will lose roughly 30% of its mass, so, without tidal effects, Earth will move to an orbit 1.7 AU (250 million km; 160 million mi) from the Sun when the star reaches its maximum radius. Most, if not all, remaining life will be destroyed by the Sun's increased luminosity (peaking at about 5,000 times its present level).[83] A 2008 simulation indicates that Earth's orbit will eventually decay due to tidal effects and drag, causing it to enter the Sun's atmosphere and be vaporized.[89]

text: Physical characteristics

text: Shape

text: The shape of Earth is approximately oblate spheroidal. Due to rotation, the Earth is flattened at the poles and bulging around the equator.[91] The diameter of the Earth at the equator is 43 kilometres (27 mi) larger than the pole-to-pole diameter.[92] Thus the point on the surface farthest from Earth's center of mass is the summit of the equatorial Chimborazo volcano in Ecuador.[93][94][95][96] The average diameter of the reference spheroid is 12,742 kilometres (7,918 mi). Local topography deviates from this idealized spheroid, although on a global scale these deviations are small compared to Earth's radius: The maximum deviation of only 0.17% is at the Mariana Trench (10,911 metres (35,797 ft) below local sea level), whereas Mount Everest (8,848 metres (29,029 ft) above local sea level) represents a deviation of 0.14%.[n 13]

text: In geodesy, the exact shape that Earth's oceans would adopt in the absence of land and perturbations such as tides and winds is called the geoid. More precisely, the geoid is the surface of gravitational equipotential at mean sea level.

text: Chemical composition

text:
Chemical composition of the crust[98][99]

Compound

Formula

Composition

Continental

Oceanic

silica

SiO2

60.6%

48.6%

alumina

Al2O3

15.9%

16.5%

lime

CaO

6.41%

12.3%

magnesia

MgO

4.66%

6.8%

iron oxide

FeOT

6.71%

6.2%

sodium oxide

Na2O

3.07%

2.6%

potassium oxide

K2O

1.81%

0.4%

titanium dioxide

TiO2

0.72%

1.4%

phosphorus pentoxide

P2O5

0.13%

0.3%

manganese oxide

MnO

0.10%

1.4%

Total

100.1%

99.9%

text: Earth's mass is approximately 7024597000000000000♠5.97×1024 kg (5,970 Yg). It is composed mostly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8%), calcium (1.5%), and aluminium (1.4%), with the remaining 1.2% consisting of trace amounts of other elements. Due to mass segregation, the core region is estimated to be primarily composed of iron (88.8%), with smaller amounts of nickel (5.8%), sulfur (4.5%), and less than 1% trace elements.[100]

text: The most common rock constituents of the crust are nearly all oxides: chlorine, sulfur, and fluorine are the important exceptions to this and their total amount in any rock is usually much less than 1%. Over 99% of the crust is composed of 11 oxides, principally silica, alumina, iron oxides, lime, magnesia, potash, and soda.[101][100][102]

text: Internal structure

text: Earth's interior, like that of the other terrestrial planets, is divided into layers by their chemical or physical (rheological) properties. The outer layer is a chemically distinct silicate solid crust, which is underlain by a highly viscous solid mantle. The crust is separated from the mantle by the Mohorovičić discontinuity. The thickness of the crust varies from about 6 kilometres (3.7 mi) under the oceans to 30–50 km (19–31 mi) for the continents. The crust and the cold, rigid, top of the upper mantle are collectively known as the lithosphere, and it is of the lithosphere that the tectonic plates are composed. Beneath the lithosphere is the asthenosphere, a relatively low-viscosity layer on which the lithosphere rides. Important changes in crystal structure within the mantle occur at 410 and 660 km (250 and 410 mi) below the surface, spanning a transition zone that separates the upper and lower mantle. Beneath the mantle, an extremely low viscosity liquid outer core lies above a solid inner core.[103] The Earth's inner core might rotate at a slightly higher angular velocity than the remainder of the planet, advancing by 0.1–0.5° per year.[104] The radius of the inner core is about one fifth of that of Earth.

text:
Geologic layers of Earth[105]

Earth cutaway from core to exosphere. Not to scale.

Depth[106]km

Component layer

Densityg/cm3

0–60

Lithosphere[n 14]

—

0–35

Crust[n 15]

2.2–2.9

35–60

Upper mantle

3.4–4.4

  35–2890

Mantle

3.4–5.6

100–700

Asthenosphere

—

2890–5100

Outer core

9.9–12.2

5100–6378

Inner core

12.8–13.1

text: Heat

text: Earth's internal heat comes from a combination of residual heat from planetary accretion (about 20%) and heat produced through radioactive decay (80%).[107] The major heat-producing isotopes within Earth are potassium-40, uranium-238, and thorium-232.[108] At the center, the temperature may be up to 6,000 °C (10,830 °F),[109] and the pressure could reach 360 GPa (52 million psi).[110] Because much of the heat is provided by radioactive decay, scientists postulate that early in Earth's history, before isotopes with short half-lives were depleted, Earth's heat production was much higher. At approximately 7016946728000000000♠3 Gyr, twice the present-day heat would have been produced, increasing the rates of mantle convection and plate tectonics, and allowing the production of uncommon igneous rocks such as komatiites that are rarely formed today.[107][111]

text:
Present-day major heat-producing isotopes[112]

Isotope

Heat releaseW/kg isotope

Half-lifeyears

Mean mantle concentrationkg isotope/kg mantle

Heat releaseW/kg mantle

238U

6995946000000000000♠94.6×10−6

7009447000000000000♠4.47×109

6992308000000000000♠30.8×10−9

6988291000000000000♠2.91×10−12

235U

6996569000000000000♠569×10−6

7008704000000000000♠0.704×109

6990220000000000000♠0.22×10−9

6987125000000000000♠0.125×10−12

232Th

6995263999999999999♠26.4×10−6

7010140000000000000♠14.0×109

6993124000000000000♠124×10−9

6988327000000000000♠3.27×10−12

40K

6995292000000000000♠29.2×10−6

7009125000000000000♠1.25×109

6992369000000000000♠36.9×10−9

6988108000000000000♠1.08×10−12

text: The mean heat loss from Earth is 7001870000000000000♠87 mW m−2, for a global heat loss of 7013442000000000000♠4.42×1013 W.[113] A portion of the core's thermal energy is transported toward the crust by mantle plumes, a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts.[114] More of the heat in Earth is lost through plate tectonics, by mantle upwelling associated with mid-ocean ridges. The final major mode of heat loss is through conduction through the lithosphere, the majority of which occurs under the oceans because the crust there is much thinner than that of the continents.[115]

text: Tectonic plates

text:
Earth's major plates[116]

Plate name

Area106 km2

  Pacific Plate
103.3

  African Plate[n 16]
78.0

  North American Plate
75.9

  Eurasian Plate
67.8

  Antarctic Plate
60.9

  Indo-Australian Plate
47.2

  South American Plate
43.6

text: Earth's mechanically rigid outer layer, the lithosphere, is divided into tectonic plates. These plates are rigid segments that move relative to each other at one of three boundaries types: At convergent boundaries, two plates come together; at divergent boundaries, two plates are pulled apart; and at transform boundaries, two plates slide past one another laterally. Along these plate boundaries, earthquakes, volcanic activity, mountain-building, and oceanic trench formation can occur.[117] The tectonic plates ride on top of the asthenosphere, the solid but less-viscous part of the upper mantle that can flow and move along with the plates.[118]

text: As the tectonic plates migrate, oceanic crust is subducted under the leading edges of the plates at convergent boundaries. At the same time, the upwelling of mantle material at divergent boundaries creates mid-ocean ridges. The combination of these processes recycles the oceanic crust back into the mantle. Due to this recycling, most of the ocean floor is less than 7015315576000000000♠100 Ma old. The oldest oceanic crust is located in the Western Pacific and is estimated to be 7015631152000000000♠200 Ma old.[119][120] By comparison, the oldest dated continental crust is 7017127177128000000♠4,030 Ma.[121]

text: The seven major plates are the Pacific, North American, Eurasian, African, Antarctic, Indo-Australian, and South American. Other notable plates include the Arabian Plate, the Caribbean Plate, the Nazca Plate off the west coast of South America and the Scotia Plate in the southern Atlantic Ocean. The Australian Plate fused with the Indian Plate between 7001500000000000000♠50 and 55 Mya. The fastest-moving plates are the oceanic plates, with the Cocos Plate advancing at a rate of 75 mm/a (3.0 in/year)[122] and the Pacific Plate moving 52–69 mm/a (2.0–2.7 in/year). At the other extreme, the slowest-moving plate is the Eurasian Plate, progressing at a typical rate of 21 mm/a (0.83 in/year).[123]

text: Surface

text: The total surface area of Earth is about 510 million km2 (197 million sq mi).[13] Of this, 70.8%,[13] or 361.13 million km2 (139.43 million sq mi), is below sea level and covered by ocean water.[124] Below the ocean's surface are much of the continental shelf, mountains, volcanoes,[92] oceanic trenches, submarine canyons, oceanic plateaus, abyssal plains, and a globe-spanning mid-ocean ridge system. The remaining 29.2%, or 148.94 million km2 (57.51 million sq mi), not covered by water has terrain that varies greatly from place to place and consists of mountains, deserts, plains, plateaus, and other landforms. Tectonics and erosion, volcanic eruptions, flooding, weathering, glaciation, the growth of coral reefs, and meteorite impacts are among the processes that constantly reshape the Earth's surface over geological time.[125][126]

text: The continental crust consists of lower density material such as the igneous rocks granite and andesite. Less common is basalt, a denser volcanic rock that is the primary constituent of the ocean floors.[127] Sedimentary rock is formed from the accumulation of sediment that becomes buried and compacted together. Nearly 75% of the continental surfaces are covered by sedimentary rocks, although they form about 5% of the crust.[128] The third form of rock material found on Earth is metamorphic rock, which is created from the transformation of pre-existing rock types through high pressures, high temperatures, or both. The most abundant silicate minerals on Earth's surface include quartz, feldspars, amphibole, mica, pyroxene and olivine.[129] Common carbonate minerals include calcite (found in limestone) and dolomite.[130]

text: The elevation of the land surface varies from the low point of −418 m (−1,371 ft) at the Dead Sea, to a maximum altitude of 8,848 m (29,029 ft) at the top of Mount Everest. The mean height of land above sea level is about 797 m (2,615 ft).[131]

text: The pedosphere is the outermost layer of Earth's continental surface and is composed of soil and subject to soil formation processes. The total arable land is 10.9% of the land surface, with 1.3% being permanent cropland.[132][133] Close to 40% of Earth's land surface is used for agriculture, or an estimated 16.7 million km2 (6.4 million sq mi) of cropland and 33.5 million km2 (12.9 million sq mi) of pastureland.[134]

text: Hydrosphere

text: The abundance of water on Earth's surface is a unique feature that distinguishes the "Blue Planet" from other planets in the Solar System. Earth's hydrosphere consists chiefly of the oceans, but technically includes all water surfaces in the world, including inland seas, lakes, rivers, and underground waters down to a depth of 2,000 m (6,600 ft). The deepest underwater location is Challenger Deep of the Mariana Trench in the Pacific Ocean with a depth of 10,911.4 m (35,799 ft).[n 17][135]

text: The mass of the oceans is approximately 1.35×1018 metric tons or about 1/4400 of Earth's total mass. The oceans cover an area of 361.8 million km2 (139.7 million sq mi) with a mean depth of 3,682 m (12,080 ft), resulting in an estimated volume of 1.332 billion km3 (320 million cu mi).[136] If all of Earth's crustal surface were at the same elevation as a smooth sphere, the depth of the resulting world ocean would be 2.7 to 2.8 km (1.68 to 1.74 mi).[137][138]

text: About 97.5% of the water is saline; the remaining 2.5% is fresh water. Most fresh water, about 68.7%, is present as ice in ice caps and glaciers.[139]

text: The average salinity of Earth's oceans is about 35 grams of salt per kilogram of sea water (3.5% salt).[140] Most of this salt was released from volcanic activity or extracted from cool igneous rocks.[141] The oceans are also a reservoir of dissolved atmospheric gases, which are essential for the survival of many aquatic life forms.[142] Sea water has an important influence on the world's climate, with the oceans acting as a large heat reservoir.[143] Shifts in the oceanic temperature distribution can cause significant weather shifts, such as the El Niño–Southern Oscillation.[144]

text: Atmosphere

text: The atmospheric pressure at Earth's sea level averages 101.325 kPa (14.696 psi),[145] with a scale height of about 8.5 km (5.3 mi).[3] A dry atmosphere is composed of 78.084% nitrogen, 20.946% oxygen, 0.934% argon, and trace amounts of carbon dioxide and other gaseous molecules.[145] Water vapor content varies between 0.01% and 4%[145] but averages about 1%.[3] The height of the troposphere varies with latitude, ranging between 8 km (5 mi) at the poles to 17 km (11 mi) at the equator, with some variation resulting from weather and seasonal factors.[146]

text: Earth's biosphere has significantly altered its atmosphere. Oxygenic photosynthesis evolved 7000270000000000000♠2.7 Gya, forming the primarily nitrogen–oxygen atmosphere of today.[72] This change enabled the proliferation of aerobic organisms and, indirectly, the formation of the ozone layer due to the subsequent conversion of atmospheric O2 into O3. The ozone layer blocks ultraviolet solar radiation, permitting life on land.[147] Other atmospheric functions important to life include transporting water vapor, providing useful gases, causing small meteors to burn up before they strike the surface, and moderating temperature.[148] This last phenomenon is known as the greenhouse effect: trace molecules within the atmosphere serve to capture thermal energy emitted from the ground, thereby raising the average temperature. Water vapor, carbon dioxide, methane, nitrous oxide, and ozone are the primary greenhouse gases in the atmosphere. Without this heat-retention effect, the average surface temperature would be −18 °C (0 °F), in contrast to the current +15 °C (59 °F),[149] and life on Earth probably would not exist in its current form.[150] In May 2017, glints of light, seen as twinkling from an orbiting satellite a million miles away, were found to be reflected light from ice crystals in the atmosphere.[151][152]

text: Weather and climate

text: Earth's atmosphere has no definite boundary, slowly becoming thinner and fading into outer space. Three-quarters of the atmosphere's mass is contained within the first 11 km (6.8 mi) of the surface. This lowest layer is called the troposphere. Energy from the Sun heats this layer, and the surface below, causing expansion of the air. This lower-density air then rises and is replaced by cooler, higher-density air. The result is atmospheric circulation that drives the weather and climate through redistribution of thermal energy.[153]

text: The primary atmospheric circulation bands consist of the trade winds in the equatorial region below 30° latitude and the westerlies in the mid-latitudes between 30° and 60°.[154] Ocean currents are also important factors in determining climate, particularly the thermohaline circulation that distributes thermal energy from the equatorial oceans to the polar regions.[155]

text: Water vapor generated through surface evaporation is transported by circulatory patterns in the atmosphere. When atmospheric conditions permit an uplift of warm, humid air, this water condenses and falls to the surface as precipitation.[153] Most of the water is then transported to lower elevations by river systems and usually returned to the oceans or deposited into lakes. This water cycle is a vital mechanism for supporting life on land and is a primary factor in the erosion of surface features over geological periods. Precipitation patterns vary widely, ranging from several meters of water per year to less than a millimeter. Atmospheric circulation, topographic features, and temperature differences determine the average precipitation that falls in each region.[156]

text: The amount of solar energy reaching Earth's surface decreases with increasing latitude. At higher latitudes, the sunlight reaches the surface at lower angles, and it must pass through thicker columns of the atmosphere. As a result, the mean annual air temperature at sea level decreases by about 0.4 °C (0.7 °F) per degree of latitude from the equator.[157] Earth's surface can be subdivided into specific latitudinal belts of approximately homogeneous climate. Ranging from the equator to the polar regions, these are the tropical (or equatorial), subtropical, temperate and polar climates.[158]

text: This latitudinal rule has several anomalies:

text:
Proximity to oceans moderates the climate. For example, the Scandinavian Peninsula has more moderate climate than similarly northern latitudes of northern Canada.
The wind enables this moderating effect. The windward side of a land mass experiences more moderation than the leeward side. In the Northern Hemisphere, the prevailing wind is west-to-east, and western coasts tend to be milder than eastern coasts. This is seen in Eastern North America and Western Europe, where rough continental climates appear on the east coast on parallels with mild climates on the other side of the ocean.[159] In the Southern Hemisphere, the prevailing wind is east-to-west, and the eastern coasts are milder.
The distance from the Earth to the Sun varies. The Earth is closest to the Sun (at perihelion) in January, which is summer in the Southern Hemisphere. It is furthest away (at aphelion) in July, which is summer in the Northern Hemisphere, and only 93.55% of the solar radiation from the Sun falls on a given square area of land than at perihelion. Despite this, there are larger land masses in the Northern Hemisphere, which are easier to heat than the seas. Consequently, summers are 2.3 °C (4 °F) warmer in the Northern Hemisphere than in the Southern Hemisphere under similar conditions.[160]
The climate is colder at high altitudes than at sea level because of the decreased air density.

text: The commonly used Köppen climate classification system has five broad groups (humid tropics, arid, humid middle latitudes, continental and cold polar), which are further divided into more specific subtypes.[154] The Köppen system rates regions of terrain based on observed temperature and precipitation.

text: The highest air temperature ever measured on Earth was 56.7 °C (134.1 °F) in Furnace Creek, California, in Death Valley, in 1913.[161] The lowest air temperature ever directly measured on Earth was −89.2 °C (−128.6 °F) at Vostok Station in 1983,[162] but satellites have used remote sensing to measure temperatures as low as −94.7 °C (−138.5 °F) in East Antarctica.[163] These temperature records are only measurements made with modern instruments from the 20th century onwards and likely do not reflect the full range of temperature on Earth.

text: Upper atmosphere

text: Above the troposphere, the atmosphere is usually divided into the stratosphere, mesosphere, and thermosphere.[148] Each layer has a different lapse rate, defining the rate of change in temperature with height. Beyond these, the exosphere thins out into the magnetosphere, where the geomagnetic fields interact with the solar wind.[164] Within the stratosphere is the ozone layer, a component that partially shields the surface from ultraviolet light and thus is important for life on Earth. The Kármán line, defined as 100 km above Earth's surface, is a working definition for the boundary between the atmosphere and outer space.[165]

text: Thermal energy causes some of the molecules at the outer edge of the atmosphere to increase their velocity to the point where they can escape from Earth's gravity. This causes a slow but steady loss of the atmosphere into space. Because unfixed hydrogen has a low molecular mass, it can achieve escape velocity more readily, and it leaks into outer space at a greater rate than other gases.[166] The leakage of hydrogen into space contributes to the shifting of Earth's atmosphere and surface from an initially reducing state to its current oxidizing one. Photosynthesis provided a source of free oxygen, but the loss of reducing agents such as hydrogen is thought to have been a necessary precondition for the widespread accumulation of oxygen in the atmosphere.[167] Hence the ability of hydrogen to escape from the atmosphere may have influenced the nature of life that developed on Earth.[168] In the current, oxygen-rich atmosphere most hydrogen is converted into water before it has an opportunity to escape. Instead, most of the hydrogen loss comes from the destruction of methane in the upper atmosphere.[169]

text: Gravitational field

text: The gravity of Earth is the acceleration that is imparted to objects due to the distribution of mass within the Earth. Near the Earth's surface, gravitational acceleration is approximately 9.8 m/s2 (32 ft/s2). Local differences in topography, geology, and deeper tectonic structure cause local and broad, regional differences in the Earth's gravitational field, known as gravity anomalies.[170]

text: Magnetic field

text: The main part of Earth's magnetic field is generated in the core, the site of a dynamo process that converts the kinetic energy of thermally and compositionally driven convection into electrical and magnetic field energy. The field extends outwards from the core, through the mantle, and up to Earth's surface, where it is, approximately, a dipole. The poles of the dipole are located close to Earth's geographic poles. At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10−5 T, with global magnetic dipole moment of 7.91 × 1015 T m3.[171] The convection movements in the core are chaotic; the magnetic poles drift and periodically change alignment. This causes secular variation of the main field and field reversals at irregular intervals averaging a few times every million years. The most recent reversal occurred approximately 700,000 years ago.[172][173]

text: Magnetosphere

text: The extent of Earth's magnetic field in space defines the magnetosphere. Ions and electrons of the solar wind are deflected by the magnetosphere; solar wind pressure compresses the dayside of the magnetosphere, to about 10 Earth radii, and extends the nightside magnetosphere into a long tail.[174] Because the velocity of the solar wind is greater than the speed at which waves propagate through the solar wind, a supersonic bowshock precedes the dayside magnetosphere within the solar wind.[175] Charged particles are contained within the magnetosphere; the plasmasphere is defined by low-energy particles that essentially follow magnetic field lines as Earth rotates;[176][177] the ring current is defined by medium-energy particles that drift relative to the geomagnetic field, but with paths that are still dominated by the magnetic field,[178] and the Van Allen radiation belt are formed by high-energy particles whose motion is essentially random, but otherwise contained by the magnetosphere.[174][179]

text: During magnetic storms and substorms, charged particles can be deflected from the outer magnetosphere and especially the magnetotail, directed along field lines into Earth's ionosphere, where atmospheric atoms can be excited and ionized, causing the aurora.[180]

text: Orbit and rotation

text: Rotation

text: Earth's rotation period relative to the Sun—its mean solar day—is 86,400 seconds of mean solar time (86,400.0025 SI seconds).[181] Because Earth's solar day is now slightly longer than it was during the 19th century due to tidal deceleration, each day varies between 0 and 2 SI ms longer.[182][183]

text: Earth's rotation period relative to the fixed stars, called its stellar day by the International Earth Rotation and Reference Systems Service (IERS), is 86,164.0989 seconds of mean solar time (UT1), or 23h 56m 4.0989s.[2][n 18] Earth's rotation period relative to the precessing or moving mean vernal equinox, misnamed its sidereal day, is 86,164.0905 seconds of mean solar time (UT1) (23h 56m 4.0905s).[2] Thus the sidereal day is shorter than the stellar day by about 8.4 ms.[184] The length of the mean solar day in SI seconds is available from the IERS for the periods 1623–2005[185] and 1962–2005.[186]

text: Apart from meteors within the atmosphere and low-orbiting satellites, the main apparent motion of celestial bodies in Earth's sky is to the west at a rate of 15°/h = 15'/min. For bodies near the celestial equator, this is equivalent to an apparent diameter of the Sun or the Moon every two minutes; from Earth's surface, the apparent sizes of the Sun and the Moon are approximately the same.[187][188]

text: Orbit

text: Earth orbits the Sun at an average distance of about 150 million km (93 million mi) every 365.2564 mean solar days, or one sidereal year. This gives an apparent movement of the Sun eastward with respect to the stars at a rate of about 1°/day, which is one apparent Sun or Moon diameter every 12 hours. Due to this motion, on average it takes 24 hours—a solar day—for Earth to complete a full rotation about its axis so that the Sun returns to the meridian. The orbital speed of Earth averages about 29.78 km/s (107,200 km/h; 66,600 mph), which is fast enough to travel a distance equal to Earth's diameter, about 12,742 km (7,918 mi), in seven minutes, and the distance to the Moon, 384,000 km (239,000 mi), in about 3.5 hours.[3]

text: The Moon and Earth orbit a common barycenter every 27.32 days relative to the background stars. When combined with the Earth–Moon system's common orbit around the Sun, the period of the synodic month, from new moon to new moon, is 29.53 days. Viewed from the celestial north pole, the motion of Earth, the Moon, and their axial rotations are all counterclockwise. Viewed from a vantage point above the north poles of both the Sun and Earth, Earth orbits in a counterclockwise direction about the Sun. The orbital and axial planes are not precisely aligned: Earth's axis is tilted some 23.44 degrees from the perpendicular to the Earth–Sun plane (the ecliptic), and the Earth–Moon plane is tilted up to ±5.1 degrees against the Earth–Sun plane. Without this tilt, there would be an eclipse every two weeks, alternating between lunar eclipses and solar eclipses.[3][189]

text: The Hill sphere, or the sphere of gravitational influence, of the Earth is about 1.5 million km (930,000 mi) in radius.[190][n 19] This is the maximum distance at which the Earth's gravitational influence is stronger than the more distant Sun and planets. Objects must orbit the Earth within this radius, or they can become unbound by the gravitational perturbation of the Sun.

text: Earth, along with the Solar System, is situated in the Milky Way and orbits about 28,000 light-years from its center. It is about 20 light-years above the galactic plane in the Orion Arm.[191]

text: Axial tilt and seasons

text: The axial tilt of the Earth is approximately 23.439281°[2] with the axis of its orbit plane, always pointing towards the Celestial Poles. Due to Earth's axial tilt, the amount of sunlight reaching any given point on the surface varies over the course of the year. This causes the seasonal change in climate, with summer in the Northern Hemisphere occurring when the Tropic of Cancer is facing the Sun, and winter taking place when the Tropic of Capricorn in the Southern Hemisphere faces the Sun. During the summer, the day lasts longer, and the Sun climbs higher in the sky. In winter, the climate becomes cooler and the days shorter. In northern temperate latitudes, the Sun rises north of true east during the summer solstice, and sets north of true west, reversing in the winter. The Sun rises south of true east in the summer for the southern temperate zone and sets south of true west.

text: Above the Arctic Circle, an extreme case is reached where there is no daylight at all for part of the year, up to six months at the North Pole itself, a polar night. In the Southern Hemisphere, the situation is exactly reversed, with the South Pole oriented opposite the direction of the North Pole. Six months later, this pole will experience a midnight sun, a day of 24 hours, again reversing with the South Pole.

text: By astronomical convention, the four seasons can be determined by the solstices—the points in the orbit of maximum axial tilt toward or away from the Sun—and the equinoxes, when the direction of the tilt and the direction to the Sun are perpendicular. In the Northern Hemisphere, winter solstice currently occurs around 21 December; summer solstice is near 21 June, spring equinox is around 20 March and autumnal equinox is about 22 or 23 September. In the Southern Hemisphere, the situation is reversed, with the summer and winter solstices exchanged and the spring and autumnal equinox dates swapped.[192]

text: The angle of Earth's axial tilt is relatively stable over long periods of time. Its axial tilt does undergo nutation; a slight, irregular motion with a main period of 18.6 years.[193] The orientation (rather than the angle) of Earth's axis also changes over time, precessing around in a complete circle over each 25,800 year cycle; this precession is the reason for the difference between a sidereal year and a tropical year. Both of these motions are caused by the varying attraction of the Sun and the Moon on Earth's equatorial bulge. The poles also migrate a few meters across Earth's surface. This polar motion has multiple, cyclical components, which collectively are termed quasiperiodic motion. In addition to an annual component to this motion, there is a 14-month cycle called the Chandler wobble. Earth's rotational velocity also varies in a phenomenon known as length-of-day variation.[194]

text: In modern times, Earth's perihelion occurs around 3 January, and its aphelion around 4 July. These dates change over time due to precession and other orbital factors, which follow cyclical patterns known as Milankovitch cycles. The changing Earth–Sun distance causes an increase of about 6.9%[n 20] in solar energy reaching Earth at perihelion relative to aphelion. Because the Southern Hemisphere is tilted toward the Sun at about the same time that Earth reaches the closest approach to the Sun, the Southern Hemisphere receives slightly more energy from the Sun than does the northern over the course of a year. This effect is much less significant than the total energy change due to the axial tilt, and most of the excess energy is absorbed by the higher proportion of water in the Southern Hemisphere.[195]

text: A study from 2016 suggested that Planet Nine tilted all Solar System planets, including Earth's, by about six degrees.[196]

text: Habitability

text: A planet that can sustain life is termed habitable, even if life did not originate there. Earth provides liquid water—an environment where complex organic molecules can assemble and interact, and sufficient energy to sustain metabolism.[197] The distance of Earth from the Sun, as well as its orbital eccentricity, rate of rotation, axial tilt, geological history, sustaining atmosphere, and magnetic field all contribute to the current climatic conditions at the surface.[198]

text: Biosphere

text: A planet's life forms inhabit ecosystems, whose total is sometimes said to form a "biosphere". Earth's biosphere is thought to have begun evolving about 7000350000000000000♠3.5 Gya.[72] The biosphere is divided into a number of biomes, inhabited by broadly similar plants and animals. On land, biomes are separated primarily by differences in latitude, height above sea level and humidity. Terrestrial biomes lying within the Arctic or Antarctic Circles, at high altitudes or in extremely arid areas are relatively barren of plant and animal life; species diversity reaches a peak in humid lowlands at equatorial latitudes.[199]

text: In July 2016, scientists reported identifying a set of 355 genes from the last universal common ancestor (LUCA) of all organisms living on Earth.[200]

text: Natural resources and land use

text:
Estimated human land use, 2000[201]

Land use

Mha

Cropland

1,510–1,611

Pastures

2,500–3,410

Natural forests

3,143–3,871

Planted forests

126–215

Urban areas

66–351

Unused, productive land

356–445

text: Earth has resources that have been exploited by humans. Those termed non-renewable resources, such as fossil fuels, only renew over geological timescales.

text: Large deposits of fossil fuels are obtained from Earth's crust, consisting of coal, petroleum, and natural gas. These deposits are used by humans both for energy production and as feedstock for chemical production. Mineral ore bodies have also been formed within the crust through a process of ore genesis, resulting from actions of magmatism, erosion, and plate tectonics.[202] These bodies form concentrated sources for many metals and other useful elements.

text: Earth's biosphere produces many useful biological products for humans, including food, wood, pharmaceuticals, oxygen, and the recycling of many organic wastes. The land-based ecosystem depends upon topsoil and fresh water, and the oceanic ecosystem depends upon dissolved nutrients washed down from the land.[203] In 1980, 50.53 million km2 (19.51 million sq mi) of Earth's land surface consisted of forest and woodlands, 67.88 million km2 (26.21 million sq mi) was grasslands and pasture, and 15.01 million km2 (5.80 million sq mi) was cultivated as croplands.[204] The estimated amount of irrigated land in 1993 was 2,481,250 km2 (958,020 sq mi).[14] Humans also live on the land by using building materials to construct shelters.

text: Natural and environmental hazards

text: Large areas of Earth's surface are subject to extreme weather such as tropical cyclones, hurricanes, or typhoons that dominate life in those areas. From 1980 to 2000, these events caused an average of 11,800 human deaths per year.[205] Many places are subject to earthquakes, landslides, tsunamis, volcanic eruptions, tornadoes, sinkholes, blizzards, floods, droughts, wildfires, and other calamities and disasters.

text: Many localized areas are subject to human-made pollution of the air and water, acid rain and toxic substances, loss of vegetation (overgrazing, deforestation, desertification), loss of wildlife, species extinction, soil degradation, soil depletion and erosion.

text: There is a scientific consensus linking human activities to global warming due to industrial carbon dioxide emissions. This is predicted to produce changes such as the melting of glaciers and ice sheets, more extreme temperature ranges, significant changes in weather and a global rise in average sea levels.[206]

text: Human geography

text: North America  South America  Antarctica     Europe  Africa     Asia  Australia vte

text: Cartography, the study and practice of map-making, and geography, the study of the lands, features, inhabitants and phenomena on Earth, have historically been the disciplines devoted to depicting Earth. Surveying, the determination of locations and distances, and to a lesser extent navigation, the determination of position and direction, have developed alongside cartography and geography, providing and suitably quantifying the requisite information.

text: Earth's human population reached approximately seven billion on 31 October 2011.[208] Projections indicate that the world's human population will reach 9.2 billion in 2050.[209] Most of the growth is expected to take place in developing nations. Human population density varies widely around the world, but a majority live in Asia. By 2020, 60% of the world's population is expected to be living in urban, rather than rural, areas.[210]

text: It is estimated that one-eighth of Earth's surface is suitable for humans to live on – three-quarters of Earth's surface is covered by oceans, leaving one-quarter as land. Half of that land area is desert (14%),[211] high mountains (27%),[212] or other unsuitable terrains. The northernmost permanent settlement in the world is Alert, on Ellesmere Island in Nunavut, Canada.[213] (82°28′N) The southernmost is the Amundsen–Scott South Pole Station, in Antarctica, almost exactly at the South Pole. (90°S)

text: Independent sovereign nations claim the planet's entire land surface, except for some parts of Antarctica, a few land parcels along the Danube river's western bank, and the unclaimed area of Bir Tawil between Egypt and Sudan. As of  2015[update], there are 193 sovereign states that are member states of the United Nations, plus two observer states and 72 dependent territories and states with limited recognition.[14] Earth has never had a sovereign government with authority over the entire globe, although some nation-states have striven for world domination and failed.[214]

text: The United Nations is a worldwide intergovernmental organization that was created with the goal of intervening in the disputes between nations, thereby avoiding armed conflict.[215] The U.N. serves primarily as a forum for international diplomacy and international law. When the consensus of the membership permits, it provides a mechanism for armed intervention.[216]

text: The first human to orbit Earth was Yuri Gagarin on 12 April 1961.[217] In total, about 487 people have visited outer space and reached orbit as of  30 July 2010[update], and, of these, twelve have walked on the Moon.[218][219][220] Normally, the only humans in space are those on the International Space Station. The station's crew, made up of six people, is usually replaced every six months.[221] The farthest that humans have traveled from Earth is 400,171 km (248,655 mi), achieved during the Apollo 13 mission in 1970.[222]

text: Moon

text:
Characteristics

Diameter
7006347480000000000♠3,474.8 km

Mass
7022734900000000000♠7.349×1022 kg

Semi-major axis
7008384400000000000♠384,400 km

Orbital period
27d 7h 43.7m

text: The Moon is a relatively large, terrestrial, planet-like natural satellite, with a diameter about one-quarter of Earth's. It is the largest moon in the Solar System relative to the size of its planet, although Charon is larger relative to the dwarf planet Pluto. The natural satellites of other planets are also referred to as "moons", after Earth's.

text: The gravitational attraction between Earth and the Moon causes tides on Earth. The same effect on the Moon has led to its tidal locking: its rotation period is the same as the time it takes to orbit Earth. As a result, it always presents the same face to the planet. As the Moon orbits Earth, different parts of its face are illuminated by the Sun, leading to the lunar phases; the dark part of the face is separated from the light part by the solar terminator.

text: Due to their tidal interaction, the Moon recedes from Earth at the rate of approximately 38 mm/a (1.5 in/year). Over millions of years, these tiny modifications—and the lengthening of Earth's day by about 23 µs/yr—add up to significant changes.[223] During the Devonian period, for example, (approximately 7002410000000000000♠410 Mya) there were 400 days in a year, with each day lasting 21.8 hours.[224]

text: The Moon may have dramatically affected the development of life by moderating the planet's climate. Paleontological evidence and computer simulations show that Earth's axial tilt is stabilized by tidal interactions with the Moon.[28] Some theorists think that without this stabilization against the torques applied by the Sun and planets to Earth's equatorial bulge, the rotational axis might be chaotically unstable, exhibiting chaotic changes over millions of years, as appears to be the case for Mars.[225]

text: Viewed from Earth, the Moon is just far enough away to have almost the same apparent-sized disk as the Sun. The angular size (or solid angle) of these two bodies match because, although the Sun's diameter is about 400 times as large as the Moon's, it is also 400 times more distant.[188] This allows total and annular solar eclipses to occur on Earth.

text: The most widely accepted theory of the Moon's origin, the giant-impact hypothesis, states that it formed from the collision of a Mars-size protoplanet called Theia with the early Earth. This hypothesis explains (among other things) the Moon's relative lack of iron and volatile elements and the fact that its composition is nearly identical to that of Earth's crust.[226]

text: Asteroids and artificial satellites

text: Earth has at least five co-orbital asteroids, including 3753 Cruithne and 2002 AA29.[227][228] A trojan asteroid companion, 2010 TK7, is librating around the leading Lagrange triangular point, L4, in the Earth's orbit around the Sun.[229][230]

text: The tiny near-Earth asteroid 2006 RH120 makes close approaches to the Earth–Moon system roughly every twenty years. During these approaches, it can orbit Earth for brief periods of time.[231]

text: As of  April 2018[update], there are 1,886 operational, human-made satellites orbiting Earth.[5] There are also inoperative satellites, including Vanguard 1, the oldest satellite currently in orbit, and over 16,000 pieces of tracked space debris.[n 3] Earth's largest artificial satellite is the International Space Station.

text: Cultural and historical viewpoint

text: The standard astronomical symbol of Earth consists of a cross circumscribed by a circle, ,[232] representing the four corners of the world.

text: Human cultures have developed many views of the planet. Earth is sometimes personified as a deity. In many cultures it is a mother goddess that is also the primary fertility deity,[233] and by the mid-20th century, the Gaia Principle compared Earth's environments and life as a single self-regulating organism leading to broad stabilization of the conditions of habitability.[234][235][236] Creation myths in many religions involve the creation of Earth by a supernatural deity or deities.[233]

text: Scientific investigation has resulted in several culturally transformative shifts in people's view of the planet. Initial belief in a flat Earth was gradually displaced in the Greek colonies of southern Italy during the late 6th century BC by the idea of spherical Earth,[237][238][239] which was attributed to both the philosophers Pythagoras and Parmenides.[238][239] By the end of the 5th century BC, the sphericity of Earth was universally accepted among Greek intellectuals.[240] Earth was generally believed to be the center of the universe until the 16th century, when scientists first conclusively demonstrated that it was a moving object, comparable to the other planets in the Solar System.[241] Due to the efforts of influential Christian scholars and clerics such as James Ussher, who sought to determine the age of Earth through analysis of genealogies in Scripture, Westerners before the 19th century generally believed Earth to be a few thousand years old at most. It was only during the 19th century that geologists realized Earth's age was at least many millions of years.[242]

text: Lord Kelvin used thermodynamics to estimate the age of Earth to be between 20 million and 400 million years in 1864, sparking a vigorous debate on the subject; it was only when radioactivity and radioactive dating were discovered in the late 19th and early 20th centuries that a reliable mechanism for determining Earth's age was established, proving the planet to be billions of years old.[243][244] The perception of Earth shifted again in the 20th century when humans first viewed it from orbit, and especially with photographs of Earth returned by the Apollo program.[245]


document_title: Hydrogen peroxide

question_text: why hydrogen peroxide is used as bleaching agent

question_tokens: why hydrogen peroxide is used as bleaching agent

root

text: Hydrogen peroxide

text: Properties[edit]

text:
The boiling point of H
2O
2 has been extrapolated as being 150.2 °C, approximately 50 °C higher than water. In practice hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure.[5]

tag: p

text: Aqueous solutions[edit]

text: In aqueous solutions hydrogen peroxide differs from the pure material due to the effects of hydrogen bonding between water and hydrogen peroxide molecules. Hydrogen peroxide and water form a eutectic mixture, exhibiting freezing-point depression; pure water has a melting point of 0 °C and pure hydrogen peroxide of −0.43 °C. The boiling point of the same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14 °C greater than that of pure water and 36.2 °C less than that of pure hydrogen peroxide.[6]

text:
Density of aqueous solution of H2O2

H2O2 (w/w)
Density (g/cm3)
Temperature (°C)

3%
1.0095
15

27%
1.10
20

35%
1.13
20

50%
1.20
20

70%
1.29
20

75%
1.33
20

96%
1.42
20

98%
1.43
20

100%
1.450
20

tag: table

text: Structure[edit]

text:
Hydrogen peroxide (H
2O
2) is a nonplanar molecule with (twisted) C2 symmetry. Although the O−O bond is a single bond, the molecule has a relatively high rotational barrier of 2460 cm−1 (29.45 kJ/mol);[7] for comparison, the rotational barrier for ethane is 12.5 kJ/mol. The increased barrier is ascribed to repulsion between the lone pairs of the adjacent oxygen atoms and results in hydrogen peroxide displaying atropisomerism.

text:
The molecular structures of gaseous and crystalline H
2O
2 are significantly different. This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state.[8] Crystals of H
2O
2 are tetragonal with the space group D4
4P4121.[9]

text:
Properties of H2O2 and its analogues
values marked * are extrapolated

Name
Formula
Molar mass (g/mol)
TM (°C)
TB (°C)

Hydrogen peroxide
HOOH
34.01
−0.43
150.2*

Water
HOH
18.02
0.00
99.98

Hydrogen disulfide
HSSH
66.15
−89.6
70.7

Hydrazine
H2NNH2
32.05
2
114

Hydroxylamine
NH2OH
33.03
33
58*

Diphosphane
H2PPH2
65.98
−99
63.5*

text: Comparison with analogues[edit]

text: Hydrogen peroxide has several structural analogues with Hm−X−X−Hn bonding arrangements (water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, N, S). Its melting point is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising significantly more readily, indicative of particularly strong hydrogen bonding. Diphosphane and hydrogen disulfide exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. All of these analogues are thermodynamically unstable. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent lone pairs.

text: Discovery[edit]

text: Hydrogen peroxide was first described in 1818 by Louis Jacques Thénard, who produced it by treating barium peroxide with nitric acid.[10] An improved version of this process used hydrochloric acid, followed by addition of sulfuric acid to precipitate the barium sulfate byproduct. Thénard's process was used from the end of the 19th century until the middle of the 20th century.[11]

text: Pure hydrogen peroxide was long believed to be unstable, as early attempts to separate it from the water, which is present during synthesis, all failed. This instability was due to traces of impurities (transition-metal salts), which catalyze the decomposition of the hydrogen peroxide. Pure hydrogen peroxide was first obtained in 1894—almost 80 years after its discovery—by Richard Wolffenstein, who produced it by vacuum distillation.[12]

text: Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892 the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by freezing-point depression, which confirmed that its molecular formula is H2O2.[13] At least half a dozen hypothetical molecular structures seemed to be consistent with the available evidence.[14] In 1934, the English mathematical physicist William Penney and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide that was very similar to the presently accepted one.[15]

text: Manufacture[edit]

text:
Previously, hydrogen peroxide was prepared industrially by hydrolysis of the ammonium peroxydisulfate, which was itself obtained by the electrolysis of a solution of ammonium bisulfate (NH
4HSO
4) in sulfuric acid:

text: Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process, which was formalized in 1936 and patented in 1939. It begins with the reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by hydrogenation on a palladium catalyst; the anthrahydroquinone then undergoes autoxidation to regenerate the starting anthraquinone, with hydrogen peroxide as a by-product. Most commercial processes achieve oxidation by bubbling compressed air through a solution of the derivatized anthracene, whereby the oxygen present in the air reacts with the labile hydrogen atoms (of the hydroxy groups), giving hydrogen peroxide and regenerating the anthraquinone. Hydrogen peroxide is then extracted, and the anthraquinone derivative is reduced back to the dihydroxy (anthracene) compound using hydrogen gas in the presence of a metal catalyst. The cycle then repeats itself.[16][17]

text: The simplified overall equation for the process is simple:[16]

text: The economics of the process depend heavily on effective recycling of the quinone (which is expensive) and extraction solvents, and of the hydrogenation catalyst.

text: A process to produce hydrogen peroxide directly from the elements has been of interest for many years. Direct synthesis is difficult to achieve, as the reaction of hydrogen with oxygen thermodynamically favours production of water. Systems for direct synthesis have been developed, most of which are based around finely dispersed metal catalysts.[18][19] None of these has yet reached a point where they can be used for industrial-scale synthesis.

text: Availability[edit]

text: Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of the volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as the concentration increases above 68%) these grades are potentially far more hazardous and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers.

text:
In 1994, world production of H
2O
2 was around 1.9 million tonnes and grew to 2.2 million in 2006,[20] most of which was at a concentration of 70% or less. In that year bulk 30% H
2O
2 sold for around 0.54 USD/kg, equivalent to 1.50 USD/kg (0.68 USD/lb) on a "100% basis".[21]

text: Reactions[edit]

text: Decomposition[edit]

text: Hydrogen peroxide is thermodynamically unstable and decomposes to form water and oxygen with a ΔHo of −98.2 kJ/mol and a ΔS of 70.5 J/(mol·K):

text: The rate of decomposition increases with rising temperature, concentration and pH, with cool, dilute, acidic solutions showing the best stability. Decomposition is catalysed by various compounds, including most transition metals and their compounds (e.g. manganese dioxide, silver, and platinum).[22] Certain metal ions, such as Fe2+ or Ti3+, can cause the decomposition to take a different path, with free radicals such as (HO·) and (HOO·) being formed. Non-metallic catalysts include potassium iodide, which reacts particularly rapidly and forms the basis of the elephant toothpaste experiment. Hydrogen peroxide can also be decomposed biologically by the enzyme catalase. The decomposition of hydrogen peroxide liberates oxygen and heat; this can be dangerous, as spilling high-concentration hydrogen peroxide on a flammable substance can cause an immediate fire.

text: Redox reactions[edit]

text: Hydrogen peroxide exhibits oxidizing and reducing properties, depending on pH.

text:
In acidic solutions, H
2O
2 is one of the most powerful oxidizers known—stronger than chlorine, chlorine dioxide, and potassium permanganate. Also, through catalysis, H
2O
2 can be converted into hydroxyl radicals (·OH), which are highly reactive.

text:
Oxidant/reduced product
Oxidation potential, V

fluorine/hydrogen fluoride
3.0

ozone/oxygen
2.1

hydrogen peroxide/water
1.8

potassium permanganate/manganese dioxide
1.7

chlorine dioxide/HClO
1.5

chlorine/chloride
1.4

text: In acidic solutions Fe2+ is oxidized to Fe3+ (hydrogen peroxide acting as an oxidizing agent):

text:
and sulfite (SO2−
3) is oxidized to sulfate (SO2−
4). However, potassium permanganate is reduced to Mn2+ by acidic H
2O
2. Under alkaline conditions, however, some of these reactions reverse; for example, Mn2+ is oxidized to Mn4+ (as MnO
2).

text: In basic solution, hydrogen peroxide can reduce a variety of inorganic ions. When it acts as a reducing agent, oxygen gas is also produced. For example, hydrogen peroxide will reduce sodium hypochlorite and potassium permanganate, which is a convenient method for preparing oxygen in the laboratory:

text: Organic reactions[edit]

text: Hydrogen peroxide is frequently used as an oxidizing agent. Illustrative is oxidation of thioethers to sulfoxides:[23][24]

text: Alkaline hydrogen peroxide is used for epoxidation of electron-deficient alkenes such as acrylic acid derivatives, and for the oxidation of alkylboranes to alcohols, the second step of hydroboration-oxidation. It is also the principal reagent in the Dakin oxidation process.

text: Precursor to other peroxide compounds[edit]

text: Hydrogen peroxide is a weak acid, forming hydroperoxide or peroxide salts with many metals.

text:
It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, chromic acid (CrO
3)[clarify] forms an unstable blue peroxide CrO(O
2)
2.

text: This kind of reaction is used industrially to produce peroxoanions. For example, reaction with borax leads to sodium perborate, a bleach used in laundry detergents:

text:
H
2O
2 converts carboxylic acids (RCO2H) into peroxy acids (RC(O)O2H), which are themselves used as oxidizing agents. Hydrogen peroxide reacts with acetone to form acetone peroxide and with ozone to form trioxidane. Hydrogen peroxide forms stable adducts with urea (hydrogen peroxide - urea), sodium carbonate (sodium percarbonate) and other compounds.[25] An acid-base adduct with triphenylphosphine oxide is a useful "carrier" for H
2O
2 in some reactions.

text: Biological function[edit]

text: Hydrogen peroxide is also one of the two chief chemicals in the defence system of the bombardier beetle, reacting with hydroquinone to discourage predators.

text: A study published in Nature found that hydrogen peroxide plays a role in the immune system. Scientists found that hydrogen peroxide presence inside cells increased after tissues are damaged in zebrafish, which is thought to act as a signal to white blood cells to converge on the site and initiate the healing process. When the genes required to produce hydrogen peroxide were disabled, white blood cells did not accumulate at the site of damage. The experiments were conducted on fish; however, because fish are genetically similar to humans, the same process is speculated to occur in humans. The study in Nature suggested asthma sufferers have higher levels of hydrogen peroxide in their lungs than healthy people, which could explain why asthma sufferers have inappropriate levels of white blood cells in their lungs.[26][27]

text: Hydrogen peroxide has important roles as a signalling molecule in the regulation of a wide variety of biological processes.[28] The compound is a major factor implicated in the free-radical theory of aging, based on how readily hydrogen peroxide can decompose into a hydroxyl radical and how superoxide radical byproducts of cellular metabolism can react with ambient water to form hydrogen peroxide.[29] These hydroxyl radicals in turn readily react with and damage vital cellular components, especially those of the mitochondria.[30][31][32] At least one study has also tried to link hydrogen peroxide production to cancer.[33] These studies have frequently been quoted in fraudulent treatment claims.[citation needed]

text: The amount of hydrogen peroxide in biological systems can be assayed using a fluorimetric assay.[34]

text: Uses[edit]

text: Industrial[edit]

text: About 60% of the world's production of hydrogen peroxide is used for pulp- and paper-bleaching.[20] The second major industrial application is the manufacture of sodium percarbonate and sodium perborate which are used as mild bleaches in laundry detergents.

text: It is used in the production of various organic peroxides with dibenzoyl peroxide being a high volume example. This is used in polymerisations, as a flour bleaching agent and as a treatment for acne. Peroxy acids, such as peracetic acid and meta-chloroperoxybenzoic acid are also typically produced using hydrogen peroxide.

text: Hydrogen peroxide is used in certain waste-water treatment processes to remove organic impurities. This is achieved by advanced oxidation processes, such as the Fenton reaction,[35][36] which use it to generate highly reactive hydroxyl radicals (·OH). These are able to destroy organic contaminates which are ordinarily difficult to remove, such as aromatic or halogenated compounds.[37] It can also oxidize sulfur based compounds present in the waste; which is beneficial as it generally reduces their odour.[38]

text: Medical[edit]

text: Disinfectant[edit]

text: Hydrogen peroxide can be used for the sterilization of various surfaces,[39] including surgical tools[40] and may be deployed as a vapour (VHP) for room sterilization.[41] H2O2 demonstrates broad-spectrum efficacy against viruses, bacteria, yeasts, and bacterial spores.[42] In general, greater activity is seen against Gram-positive than Gram-negative bacteria; however, the presence of catalase or other peroxidases in these organisms can increase tolerance in the presence of lower concentrations.[43] Higher concentrations of H2O2 (10 to 30%) and longer contact times are required for sporicidal activity.[44]

text: Hydrogen peroxide is seen as an environmentally safe alternative to chlorine-based bleaches, as it degrades to form oxygen and water and it is generally recognized as safe as an antimicrobial agent by the U.S. Food and Drug Administration (FDA).[45]

text: Historically hydrogen peroxide was used for disinfecting wounds, partly because of its low cost and prompt availability compared to other antiseptics. It is now thought to slow healing and lead to scarring because it destroys newly formed skin cells.[46] Only a very low concentration of H2O2 can induce healing, and only if not repeatedly applied.[47] Surgical use can lead to gas embolism formation.[48][49] Despite this it is still used for wound treatment in many developing countries.[50][51]

text: Dermal exposure to dilute solutions of hydrogen peroxide cause whitening or bleaching of the skin due to microembolism caused by oxygen bubbles in the capillaries.[52]

text: Cosmetic applications[edit]

text:
Diluted H
2O
2 (between 1.9% and 12%) mixed with ammonium hydroxide is used to bleach human hair. The chemical's bleaching property lends its name to the phrase "peroxide blonde".[53] Hydrogen peroxide is also used for tooth whitening. It can be found in most whitening toothpastes. Hydrogen peroxide has shown positive results involving teeth lightness and chroma shade parameters. It works by oxidizing colored pigments onto the enamel where the shade of the tooth can indeed become lighter. Hydrogen peroxide can be mixed with baking soda and salt to make a home-made toothpaste.[54]

text: Hydrogen peroxide may be used to treat acne,[55] although benzoyl peroxide is a more common treatment.

text: Use in alternative medicine[edit]

text: Practitioners of alternative medicine have advocated the use of hydrogen peroxide for the treatment of various conditions, including emphysema, influenza, AIDS and in particular cancer,[56] although the effectiveness is scientifically questionable and in some cases it may even be fatal.[57][58][59][60][61]

text: The practice calls for the daily consumption of hydrogen peroxide, either orally or by injection and is, in general, based around two precepts. First, that hydrogen peroxide is naturally produced by the body to combat infection; and second, that human pathogens (including cancer: See Warburg hypothesis) are anaerobic and cannot survive in oxygen-rich environments. The ingestion or injection of hydrogen peroxide is therefore believed to kill disease by mimicking the immune response in addition to increasing levels of oxygen within the body. This makes it similar to other oxygen-based therapies, such as ozone therapy and hyperbaric oxygen therapy.

text: Both the effectiveness and safety of hydrogen peroxide therapy is scientifically questionable. Hydrogen peroxide is produced by the immune system but in a carefully controlled manner. Cells called by phagocytes engulf pathogens and then use hydrogen peroxide to destroy them. The peroxide is toxic to both the cell and the pathogen and so is kept within a special compartment, called a phagosome. Free hydrogen peroxide will damage any tissue it encounters via oxidative stress; a process which also has been proposed as a cause of cancer.[62] Claims that hydrogen peroxide therapy increase cellular levels of oxygen have not been supported. The quantities administered would be expected to provide very little additional oxygen compared to that available from normal respiration. It should also be noted that it is difficult to raise the level of oxygen around cancer cells within a tumour, as the blood supply tends to be poor, a situation known as tumor hypoxia.

text: Large oral doses of hydrogen peroxide at a 3% concentration may cause irritation and blistering to the mouth, throat, and abdomen as well as abdominal pain, vomiting, and diarrhea.[57] Intravenous injection of hydrogen peroxide has been linked to several deaths.[59][60][61]

text: The American Cancer Society states that "there is no scientific evidence that hydrogen peroxide is a safe, effective or useful cancer treatment."[58] Furthermore, the therapy is not approved by the U.S. FDA.

text: Propellant[edit]

text:
High-concentration H
2O
2 is referred to as "high-test peroxide" (HTP). It can be used either as a monopropellant (not mixed with fuel) or as the oxidizer component of a bipropellant rocket. Use as a monopropellant takes advantage of the decomposition of 70–98% concentration hydrogen peroxide into steam and oxygen. The propellant is pumped into a reaction chamber, where a catalyst, usually a silver or platinum screen, triggers decomposition, producing steam at over 600 °C (1,112 °F), which is expelled through a nozzle, generating thrust. H
2O
2 monopropellant produces a maximal specific impulse (Isp) of 161 s (1.6 kN·s/kg). Peroxide was the first major monopropellant adopted for use in rocket applications. Hydrazine eventually replaced hydrogen-peroxide monopropellant thruster applications primarily because of a 25% increase in the vacuum specific impulse.[63] Hydrazine (toxic) and hydrogen peroxide (less-toxic [ACGIH TLV 0.01 and 1 ppm respectively]) are the only two monopropellants (other than cold gases) to have been widely adopted and utilized for propulsion and power applications. The Bell Rocket Belt, reaction-control systems for X-1, X-15, Centaur, Mercury, Little Joe, as well as the turbo-pump gas generators for X-1, X-15, Jupiter, Redstone and Viking used hydrogen peroxide as a monopropellant.[64]

text:
As a bipropellant, H
2O
2 is decomposed to burn a fuel as an oxidizer. Specific impulses as high as 350 s (3.5 kN·s/kg) can be achieved, depending on the fuel. Peroxide used as an oxidizer gives a somewhat lower Isp than liquid oxygen, but is dense, storable, noncryogenic and can be more easily used to drive gas turbines to give high pressures using an efficient closed cycle. It can also be used for regenerative cooling of rocket engines. Peroxide was used very successfully as an oxidizer in World War II German rocket motors (e.g. T-Stoff, containing oxyquinoline stabilizer, for both the Walter HWK 109-500 Starthilfe RATO externally podded monopropellant booster system, and for the Walter HWK 109-509 rocket motor series used for the Me 163B), most often used with C-Stoff in a self-igniting hypergolic combination, and for the low-cost British Black Knight and Black Arrow launchers.

text: In the 1940s and 1950s, the Hellmuth Walter KG-conceived turbine used hydrogen peroxide for use in submarines while submerged; it was found to be too noisy and require too much maintenance compared to diesel-electric power systems. Some torpedoes used hydrogen peroxide as oxidizer or propellant. Operator error in the use of hydrogen-peroxide torpedoes was named as possible causes for the sinkings of HMS Sidon and the Russian submarine Kursk.[65] SAAB Underwater Systems is manufacturing the Torpedo 2000. This torpedo, used by the Swedish Navy, is powered by a piston engine propelled by HTP as an oxidizer and kerosene as a fuel in a bipropellant system.[66][67]

text: Explosives[edit]

text: Hydrogen peroxide has been used for creating organic peroxide-based explosives, such as acetone peroxide, for improvised explosive devices. Hydrogen peroxide itself also acts as an explosive in high concentrations when placed in an absorbent, and has been used in attacks including the 7 July 2005 London bombings.[68] These explosives tend to degrade quickly and hence are not used as commercial or military explosives.

text: Other uses[edit]

text: Hydrogen peroxide has various domestic uses, primarily as a cleaning and disinfecting agent.

text: Hydrogen peroxide reacts with certain di-esters, such as phenyl oxalate ester (cyalume), to produce chemiluminescence; this application is most commonly encountered in the form of glow sticks.

text: Some horticulturalists and users of hydroponics advocate the use of weak hydrogen peroxide solution in watering solutions. Its spontaneous decomposition releases oxygen that enhances a plant's root development and helps to treat root rot (cellular root death due to lack of oxygen) and a variety of other pests.[69][70]

text: Laboratory tests conducted by fish culturists in recent years have demonstrated that common household hydrogen peroxide can be used safely to provide oxygen for small fish. The hydrogen peroxide releases oxygen by decomposition when it is exposed to catalysts such as manganese dioxide.

text: Safety[edit]

text:
Regulations vary, but low concentrations, such as 6%, are widely available and legal to buy for medical use. Most over-the-counter peroxide solutions are not suitable for ingestion. Higher concentrations may be considered hazardous and are typically accompanied by a Material Safety Data Sheet (MSDS). In high concentrations, hydrogen peroxide is an aggressive oxidizer and will corrode many materials, including human skin. In the presence of a reducing agent, high concentrations of H
2O
2 will react violently.

text: High-concentration hydrogen peroxide streams, typically above 40%, should be considered hazardous due to concentrated hydrogen peroxide's meeting the definition of a DOT oxidizer according to U.S. regulations, if released into the environment. The EPA Reportable Quantity (RQ) for D001 hazardous wastes is 100 pounds (45 kg), or approximately 10 US gallons (38 L), of concentrated hydrogen peroxide.

text: Hydrogen peroxide should be stored in a cool, dry, well-ventilated area and away from any flammable or combustible substances. It should be stored in a container composed of non-reactive materials such as stainless steel or glass (other materials including some plastics and aluminium alloys may also be suitable).[71] Because it breaks down quickly when exposed to light, it should be stored in an opaque container, and pharmaceutical formulations typically come in brown bottles that block light.[72]

text: Hydrogen peroxide, either in pure or diluted form, can pose several risks, the main one being that it forms explosive mixtures upon contact with organic compounds.[73] Highly concentrated hydrogen peroxide itself is unstable and can cause a boiling liquid expanding vapour explosion (BLEVE) of the remaining liquid. Distillation of hydrogen peroxide at normal pressures is thus highly dangerous. It is also corrosive, especially when concentrated, but even domestic-strength solutions can cause irritation to the eyes, mucous membranes and skin.[74] Swallowing hydrogen peroxide solutions is particularly dangerous, as decomposition in the stomach releases large quantities of gas (10 times the volume of a 3% solution), leading to internal bloating. Inhaling over 10% can cause severe pulmonary irritation.[75]

text: With a significant vapour pressure (1.2 kPa at 50 °C[76]), hydrogen-peroxide vapour is potentially hazardous. According to U.S. NIOSH, the immediately dangerous to life and health (IDLH) limit is only 75 ppm.[77] The U.S. Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit of 1.0 ppm calculated as an 8-hour time-weighted average (29 CFR 1910.1000, Table Z-1).[73] Hydrogen peroxide has also been classified by the American Conference of Governmental Industrial Hygienists (ACGIH) as a "known animal carcinogen, with unknown relevance on humans".[78] For workplaces where there is a risk of exposure to the hazardous concentrations of the vapours, continuous monitors for hydrogen peroxide should be used. Information on the hazards of hydrogen peroxide is available from OSHA[73] and from the ATSDR.[79]

text: Historical incidents[edit]

text:
On 16 July 1934, in Kummersdorf, Germany, a propellant tank containing an experimental monopropellant mixture consisting of hydrogen peroxide and ethanol exploded during a test, killing three people.
During the Second World War, doctors in German concentration camps experimented with the use of hydrogen peroxide injections in the killing of human subjects.[80]
Several people received minor injuries after a hydrogen-peroxide spill on board of a flight between the U.S. cities Orlando and Memphis on 28 October 1998.[81]
The Russian submarine K-141 Kursk sailed to perform an exercise of firing dummy torpedoes at the Pyotr Velikiy, a Kirov-class battlecruiser. On 12 August 2000, at 11:28 local time (07:28 UTC), there was an explosion while preparing to fire the torpedoes. The only credible report to date is that this was due to the failure and explosion of one of the Kursk's hydrogen peroxide-fueled torpedoes. It is believed that HTP, a form of highly concentrated hydrogen peroxide used as propellant for the torpedo, seeped through its container, damaged either by rust or in the loading procedure back on land where an incident involving one of the torpedoes accidentally touching ground went unreported. The vessel was lost with all hands. A similar incident was responsible for the loss of HMS Sidon in 1955.
On 15 August 2010 a spill of about 30 US gallons (110 L) of cleaning fluid occurred on the 54th floor of 1515 Broadway, in Times Square, New York City. The spill, which a spokesperson for the New York City fire department said was of hydrogen peroxide, shut down Broadway between West 42nd and West 48th streets as fire engines responded to the hazmat situation. There were no reported injuries.[82]

tag: ul


document_title: The Bet (short story)

question_text: who wins the bet in the short story the bet

text: The Bet (short story)

text: Publication[edit]

text: On 17 December 1888 Nikolai Khudekov asked Chekhov to write a story for Peterburgskaya Gazeta which he was an editor of. Chekhov came up with "The Cobbler and the Devil" (published on 25 December) and informed Alexey Suvorin of that. Suvorin, the Novoye Vremya's editor, took it almost as an insult, so Chekhov promised to produce a similar kind of fable for this newspaper before the New Year Eve. He started writing it on 22 December, and on the 30th sent the story by post.[1]

text: Divided into three parts, it appeared in the 1 January 1889, No. 4613 issue of Novoye Vremya, titled "Fairytale" (Сказка). With a new title, "The Bet", revised and cut (part 3 of the original text now has gone) it was included into Volume 4 of Chekhov's Collected Works, published in 1899–1901 by Adolf Marks.[2] "As I was reading the proofs, I came to dislike the end, it occurred to me that it was too cold and cruel," he explained the reason for the omission in 1903.[3]

text: Plot[edit]

text: As the story opens, the banker recalls the occasion of the bet fifteen years before. Guests at the party that he was hosting that day fell into a discussion of capital punishment; the banker argued that capital punishment is more humane than life imprisonment, while the young lawyer disagreed, insisting that he would choose life in prison rather than death. They agree to a bet of two million rubles that the lawyer cannot spend fifteen years in solitary confinement. The bet was on, and the lawyer cast himself into isolation for fifteen years.

text: The man spends his time in confinement reading books, writing, playing piano, studying, drinking wine, and educating himself. We find him continuously growing throughout the story. We see various phases in his term of imprisonment over the years. At first, the lawyer suffered from severe loneliness and depression. But soon he began studying vigorously. He begins with languages and other related subjects. Then, a mix of science, literature, philosophy and other seemingly random subjects. He ends up reading some six hundred volumes in the course of four years. Then, the Gospel followed by theology and histories of religion. In the final two years, the imprisoned lawyer read immensely on chemistry, medicine and philosophy, and sometimes works of Byron or Shakespeare.

text: In the meantime, the banker's fortune declines and he realizes that if he loses, paying off the bet will leave him bankrupt.

text: The day before the fifteen-year period concludes, the banker resolves to kill the lawyer so as to not owe him the money. On his way to do so, however, the banker finds a note written by the lawyer. The note declares that in his time in confinement he has learned to despise material goods as fleeting things and he believes that knowledge is worth more than money. To this end he elects to renounce the reward of the bet. The banker was moved and shocked to his bones after reading the note, kisses the strange man on the head and leaves the lodge weeping, relieved not to have to kill anyone. The prison warden later reports that the lawyer has left the guest house, thus losing the bet but proving his point that solitary confinement is more humane than death punishment as it gives a chance to a person (the lawyer in this story) to develop himself. The lawyer also unwittingly saves his own life by writing the note.

text: Characters[edit]

text: There are two major characters featured in "The Bet": the lawyer and the banker, neither of which have official names in Chekhov's short story.

text: The lawyer[edit]

text: This section possibly contains original research. Please improve it by verifying the claims made and adding inline citations. Statements consisting only of original research should be removed. (April 2014) (Learn how and when to remove this template message)

text: The lawyer is seen to be persistent, intelligent and self-motivating. He does not break down in the 15 years of imprisonment as the banker foretold. He is intelligent by the virtue of reading so many books, which reflects in his eagerness to associate with other men, rather than claiming the final prize. He starts as a young, impatient person, ready to spend 15 best years of his life for 2 million. His character of being a person with no interest in materialistic luxury is reflected when he renounces the 2 million and settles with just having proved his point.

text: The banker[edit]

text: The banker likes to be in a position of authority and likes to wield power over others, especially those who happen to disagree with him. The character changes drastically from the beginning of the story when he seems to be very free handed as he easily bets to pay two million and later, his lack of wealth drives him to dishonesty and plan for murder. This also signifies the weak character of the banker. He is very attached to the materialistic luxuries of life and values human life less than his luxuries as he plans on killing the lawyer. He plans on killing the lawyer for money and nothing but money changes his mind.