3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||18.01528(33) g/mol|
|Appearance||White crystal-like solid, almost colorless liquid with a hint of blue, colorless gas|
0.9998396 g/mL at 0 °C
0.9970474 g/mL at 25 °C
0.961893 g/mL at 95 °C
0.9167 g/ml at 0 °C
|Melting point||0.00 °C (32.00 °F; 273.15 K) [a]|
|Boiling point||99.98 °C (211.96 °F; 373.13 K) [a]|
|Solubility||Poorly soluble in haloalkanes, aliphatic and aromatic hydrocarbons, ethers. Improved solubility in carboxylates, alcohols, ketones, amines. Miscible with methanol, ethanol, propanol, isopropanol, acetone, glycerol, 1,4-dioxane, tetrahydrofuran, sulfolane, acetaldehyde, dimethylformamide, dimethoxyethane, dimethyl sulfoxide, acetonitrile. Partially miscible with Diethyl ether, Methyl Ethyl Ketone, Dichloromethane, Ethyl Acetate, Bromine.|
|Vapor pressure||3.1690 kilopascals or 0.031276 atm|
|Thermal conductivity||0.6065 W/(m·K)|
Refractive index (nD)
|1.3330 (20 °C)|
|Std enthalpy of
|−285.83 ± 0.04 kJ/mol|
|69.95 ± 0.03 J/(mol·K)|
|Specific heat capacity, C||75.385 ± 0.05 J/(mol·K)|
Avalanche (as snow)
|Other cations||Hydrogen sulfide|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Lakes, oceans, seas, and rivers are made of water. Precipitation is water that falls from clouds in the sky. It may be rain (liquid) if it is warm, or it may be frozen if it is cold. If water gets very cold (below 0 °C (32 °F)), it freezes and becomes ice, the frozen variant of water. If water gets very hot (above 100 °C (212 °F)), it boils and becomes steam or water vapor. It is moved around in the water cycle. Water is essential for life.
Physical chemistry of waterEdit
Water is a fluid. Water is the only chemical substance on Earth that exists naturally in three states. There are over 40 anomalies (strange things) about water. Unlike most other liquids such as alcohol or oil, when water freezes, it expands by about 9%. This expansion can cause pipes to break if the water inside them freezes.
Water is a molecule made of two hydrogen atoms and one oxygen atom. Its chemical formula is H2O. Like other liquids, water has a surface tension, so a little water can make drops on a surface, rather than always spreading out to wet the surface.
Things having something to do with water may have "hydro" or "aqua" in their name, such as hydropower or aquarium, from the Greek and Latin names for water. It is also called the "universal solvent", because it dissolves many other compounds.
In small amounts, water appears to have no colour but in large amounts (such as seas or lakes), it has a very light blue color.
Uses of waterEdit
Plants and animals (including people) are mostly water inside, and must drink water to live. It gives a medium for chemical reactions to take place, and is the main part of blood. It keeps the body temperature the same by sweating from the skin. Water helps blood carry nutrients from the stomach to all parts of the body to keep the body alive. Water also helps the blood carry oxygen from the lungs to the body. Saliva, which helps animals and people digest food, is mostly water. Water helps make urine. Urine helps remove bad chemicals from the body. The human body is between 60% and 70% water, but this value differs with age; i.e. a foetus is 95% water inside.
Water is the main component of drinks like milk, juice, and wine. Each type of drink also has other things that add flavor or nutrients, things like sugar, fruit, and sometimes alcohol. Water that a person can drink is called "potable water" (or "drinking water"). The water in oceans is salt water, but lakes and rivers usually have unsalted water. Only about 3% of all the water on earth is fresh water. The rest is salt water.
Though people can survive a few months without food, they can only survive for a day or two without water. A few desert animals can get enough water from their food, but the others must drink. Water has no smell,taste or color
Water is also used for recreational purposes, see list of water sports.
Dihydrogen monoxide parodyEdit
The dihydrogen monoxide parody involves calling water by the unfamiliar chemical name "dihydrogen monoxide" (DHMO) and listing some of its harmful effects in an alarming way. Some examples include talking about how "it causes burning, suffocation and corrosion," when it is actually just talking about hot water, drowning and rust. Sometimes the parody calls for it to be banned and/or labelled as dangerous.
The prank works because it takes advantage of people's misunderstanding. Calling water by an unfamiliar name and making it sound like a harmful chemical can make people think it is dangerous.
"Dihydrogen monoxide" is an alternative chemical name for water, but nobody uses it. The word "dihydrogen" means two hydrogens, and "monoxide" means one oxygen. The chemical formula of water has two hydrogens and one oxygen.
The parody gained most of its popularity in the 1990s, when a 14-year-old named Nathan Zohner collected anti-DHMO petitions for a science project about gullibility. Zohner fooled a lot of people, which has led to his project being used in lessons about critical thinking and the scientific method.
The website DHMO.org is a joke website which lists the harmful effects of water (DHMO), answers questions, and calls for it to be banned, among other things.
Origin of the Earth's waterEdit
The weirdness of waterEdit
A BBC short item explains that every molecule on Earth has existed for billions of years, and all of them came from elsewhere. Water is alien because it arrived on asteroids and comets. It is the second most common molecule in the universe. Why is it not a gas? It is made of two very light elements. Ice floating on water is also an oddity. Also, hot water freezes faster than cold, and no-one knows why this is. Molecules of water can move up against the force of gravity (that is due to surface adhesion).
Water in the universeEdit
Much of the universe's water is produced as a by-product of star formation. On 22 July 2011, a report described the discovery of a gigantic cloud of water vapor containing "140 trillion times more water than all of Earth's oceans combined" around a quasar located 12 billion light years from Earth. According to the researchers, the "discovery shows that water has been prevalent in the universe for nearly its entire existence".
Water has been detected in interstellar clouds in our galaxy, the Milky Way. Water probably exists in abundance in other galaxies, too. Its components, hydrogen and oxygen, are among the most abundant elements in the universe. Most other planetary systems are likely to have similar ingredients.
Origin of water on Earth: hypothesesEdit
We do not know exactly how the Earth came to have so much water. It is everywhere in the Universe, but rarely in such quantity. Reasoning from first principles, every element except hydrogen has been formed in stars. Therefore oxygen was originally formed in stars. The formation of water is not a problem: it is exothermic, so forming the molecule from its atoms does not need outside energy. But to explain how the Earth has so much in comparison with, for example, Mars, is not easy. It is an undecided problem in planetary geology.
It was long thought that Earth’s water did not come from the planet’s region of the protoplanetary disk. Instead, it was thought that water and other volatiles must have been delivered to Earth from the outer Solar System later in its history. But hydrogen inside the Earth did play some role in the formation of the ocean. The two ideas may each be partly right. Water was delivered to Earth by impacts from icy planetesimals (asteroids) in the outer edges of the asteroid belt. How much is not known.
Water vapor is found in:
- Atmosphere of the Sun: It has small amounts of water.
- Atmosphere of Mercury: It is composed of 3.4% of water. Mercury has large amounts of water in its exosphere.
- Atmosphere of Venus: It is composed of 0.002% of water.
- Atmosphere of Earth: It is composed of 0.4% of water all over the atmosphere. There is usually around 1–4% of water at the surface of the Earth. Water vapor is also found in the extremely thin atmosphere of the Moon in small amounts.
- Atmosphere of Mars: It is composed of 0.03% of water.
- Atmosphere of Ceres.
- Atmosphere of Jupiter: It is composed of 0.0004% ice. There is also water in its moon Europa.
- Atmosphere of Saturn: It is has water in the form of ice. Enceladus is composed of 91% of ice and ice is also in Dione's exosphere.
- Atmosphere of Uranus: Ice is found in small amounts.
- Atmosphere of Neptune: Ice is also found deep in the atmosphere of Neptune.
- The atmosphere of extrasolar planets such as HD 189733 b and HD 209458 b, Tau Boötis b, HAT-P-11b, XO-1b, WASP-12b, WASP-17b, and WASP-19b.
- Stellar atmospheres: Water vapor is found in giant hot stars such as Betelgeuse, Mu Cephei, Antares and Arcturus.
Liquid water is found on Earth. It covers about 71% of the surface of the Earth. Liquid water is sometimes found in small amounts on Mars. Scientists believe that liquid water is in Enceladus, Titan, Europa and Ganymede.
Water ice is found in:
- Mars: Water ice is found at the north and south poles of Mars.
- Earth and the Moon: It is mainly found as ice sheets on Earth and in craters and volcanic rocks in the Moon.
- Jupiter's moons: It is found on Europa, Ganymede and Callisto.
- Saturn: It is found in the planetary rings of Saturn. It is also found in Titan and Enceladus.
- Pluto and Charon
- Comets and other objects in the Kuiper belt and Oort cloud.
- "naming molecular compounds". www.iun.edu. Retrieved 1 October 2018.
Sometimes these compounds have generic or common names (e.g., H2O is "water") and they also have systematic names (e.g., H2O, dihydrogen monoxide).
- "Definition of Hydrol". Merriam-Webster.
- Riddick 1970, Table of Physical Properties, Water 0b. pg 67-8. sfn error: no target: CITEREFRiddick1970 (help)
- Lide 2003, Properties of Ice and Supercooled Water in Section 6. sfn error: no target: CITEREFLide2003 (help)
- Water in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD), http://webbook.nist.gov (retrieved 2016-5-27)
- Anatolievich, Kiper Ruslan. "Properties of substance: water".
- Lide 2003, Vapor Pressure of Water From 0 to 370° C in Sec. 6. sfn error: no target: CITEREFLide2003 (help)
- Lide 2003, Chapter 8: Dissociation Constants of Inorganic Acids and Bases. sfn error: no target: CITEREFLide2003 (help)
- Weingärtner et al. 2016, p. 13. sfn error: no target: CITEREFWeingärtner_et_al.2016 (help)
- "What is the pKa of Water". University of California, Davis. 2015-08-09.
- Silverstein, Todd P.; Heller, Stephen T. (17 April 2017). "pKa Values in the Undergraduate Curriculum: What Is the Real pKa of Water?". Journal of Chemical Education. 94 (6): 690–695. Bibcode:2017JChEd..94..690S. doi:10.1021/acs.jchemed.6b00623.
- Ramires, Maria L. V.; Castro, Carlos A. Nieto de; Nagasaka, Yuchi; Nagashima, Akira; Assael, Marc J.; Wakeham, William A. (1995-05-01). "Standard Reference Data for the Thermal Conductivity of Water". Journal of Physical and Chemical Reference Data. 24 (3): 1377–1381. Bibcode:1995JPCRD..24.1377R. doi:10.1063/1.555963. ISSN 0047-2689.
- Lide 2003, 8—Concentrative Properties of Aqueous Solutions: Density, Refractive Index, Freezing Point Depression, and Viscosity. sfn error: no target: CITEREFLide2003 (help)
- Lide 2003, 6.186. sfn error: no target: CITEREFLide2003 (help)
- Lide 2003, 9—Dipole Moments. sfn error: no target: CITEREFLide2003 (help)
- Water in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD), http://webbook.nist.gov (retrieved 2014-06-01)
- Breaking News | Oldest rock shows Earth was a hospitable young planet. Spaceflight Now (2001-01-14). Retrieved on 2012-01-27.
- "United Nations". Un.org. 2005-03-22. Retrieved 2010-07-25.
- "Forty-one anomalies of water « Fairy LoRe". fathersergio.wordpress.com. 2011. Retrieved September 1, 2011.
- "8(a) Physical Properties of Water". physicalgeography.net. 2011. Retrieved August 31, 2011.
- "Understanding the processes of erosion". mountainnature.com. 2009. Retrieved August 31, 2011.
- "iapws.org". iapws.org. 2000. Archived from the original on August 8, 2011. Retrieved August 31, 2011.
- "Surface tension is a contractive tendency of the surface of a liquid that allows it to resist an external force". Boundless. Archived from the original on June 3, 2016. Retrieved December 25, 2016.
- "Percentage of water".
- "Fresh water percentage (2)". Archived from the original on 2007-07-15. Retrieved 2008-12-11.
- Jha, Alok 2019. Why water is one of the weirdest things in the universe. BBC News Ideas. 
- "ALMA greatly improves capacity to search for water in universe". Archived from the original on 23 July 2015. Retrieved 20 July 2015.
- Melnick, Gary, Harvard-Smithsonian Center for Astrophysics and Neufeld, David, Johns Hopkins University quoted in: "Discover of water vapor near Orion nebula suggests possible origin of H20 in Solar System". The Harvard University Gazette. 1998. Archived from the original on 16 January 2000. "Space cloud holds enough water to fill Earth's oceans 1 million times". Headlines@Hopkins, JHU. 9 April 1998. Archived from the original on 9 November 2007. Retrieved 21 April 2007.
- Clavin, Whitney; Buis, Alan (22 July 2011). "Astronomers find largest, most distant reservoir of water". NASA. Archived from the original on 24 July 2011. Retrieved 25 July 2011.
- Staff (22 July 2011). "Astronomers find largest, oldest mass of water in Universe". Space.com. Archived from the original on 29 October 2011. Retrieved 23 July 2011.
- Bova, Ben (13 October 2009). Faint Echoes, Distant Stars: The Science and Politics of Finding Life Beyond Earth. Zondervan. ISBN 978-0-06-185448-4.
- Monday, Nola Taylor Redd | Published; April 1; 2019. "Where did Earths water come from". Astronomy.com. Retrieved 2020-07-16.CS1 maint: numeric names: authors list (link)
- Pepin, Robert O. 1991. On the origin and early evolution of terrestrial planet atmospheres and meteoritic volatiles. Icarus 92 (1): 2–79. 
- Solanki, S. K.; Livingston, W.; Ayres, T. (1994-01-07). "New light on the heart of darkness of the Solar chromosphere". Science. 263 (5143): 64–66. doi:10.1126/science.263.5143.64. ISSN 0036-8075.
- "MESSENGER Scientists 'astonished' to find water in Mercury's thin atmosphere - Planetary News | The Planetary Society". web.archive.org. 2010-04-06. Retrieved 2020-09-11.
- the SPICAV/SOIR team; Bertaux, Jean-Loup; Vandaele, Ann-Carine; Korablev, Oleg; Villard, E.; Fedorova, A.; Fussen, D.; Quémerais, E.; Belyaev, D. (2007-11). "A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO". Nature. 450 (7170): 646–649. doi:10.1038/nature05974. ISSN 0028-0836. Check date values in:
- Sridharan, R.; Ahmed, S.M.; Pratim Das, Tirtha; Sreelatha, P.; Pradeepkumar, P.; Naik, Neha; Supriya, Gogulapati (2010). "'Direct' evidence for water (H2O) in the sunlit lunar ambience from CHACE on MIP of Chandrayaan I". Planetary and Space Science. 58 (6): 947–950. doi:10.1016/j.pss.2010.02.013.
- Rapp, Donald, 1934- (2013). Use of extraterrestrial resources for human space missions to Moon or Mars. Berlin: Springer. ISBN 978-3-642-32762-9. OCLC 819571505.CS1 maint: multiple names: authors list (link)
- Küppers, Michael; O’Rourke, Laurence; Bockelée-Morvan, Dominique; Zakharov, Vladimir; Lee, Seungwon; von Allmen, Paul; Carry, Benoît; Teyssier, David; Marston, Anthony (2014-01). "Localized sources of water vapour on the dwarf planet (1) Ceres". Nature. 505 (7484): 525–527. doi:10.1038/nature12918. ISSN 0028-0836. Check date values in:
- Atreya, Sushil K.; Wong, Ah-San (2005-01). "Coupled clouds and chemistry of the giant planets— a case for multiprobes". Space Science Reviews. 116 (1–2): 121–136. doi:10.1007/s11214-005-1951-5. ISSN 0038-6308. Check date values in:
- "Hubble sees evidence of water vapor at Jupiter moon". NASA/JPL. Archived from the original on 2020-11-07. Retrieved 2020-09-11.
- Hansen, C. J. (2006-03-10). "Enceladus' Water Vapor Plume". Science. 311 (5766): 1422–1425. doi:10.1126/science.1121254. ISSN 0036-8075.
- Hubbard, W. B. (1997-02-28). "Neptune's Deep Chemistry". Science. 275 (5304): 1279–1280. doi:10.1126/science.275.5304.1279.
- Lockwood, Alexandra C.; Johnson, John A.; Bender, Chad F.; Carr, John S.; Barman, Travis; Richert, Alexander J. W.; Blake, Geoffrey A. (2014-02-24). "Near-IR direct detection of water vapor in Tau Bootis b". The Astrophysical Journal. 783 (2): L29. doi:10.1088/2041-8205/783/2/L29. ISSN 2041-8205.
- "NASA telescopes find clear skies and water vapor on exoplanet". NASA/JPL. Archived from the original on 2020-12-07. Retrieved 2020-09-11.
- Hanslmeier, Arnold. (2011). Water in the universe. Dordrecht: Springer. ISBN 978-90-481-9984-6. OCLC 670074794.
- Garner, Rob (2015-05-06). "Hubble Traces Subtle Signals of Water on Hazy Worlds". NASA. Retrieved 2020-09-11.
- Anderson, Gina (2015-09-28). "NASA Confirms Evidence That Liquid Water Flows on Today's Mars". NASA. Retrieved 2020-09-12.
- "NASA Space Assets Detect Ocean inside Saturn Moon". NASA/JPL. Retrieved 2020-09-12.
- Iess, L.; Stevenson, D. J.; Parisi, M.; Hemingway, D.; Jacobson, R. A.; Lunine, J. I.; Nimmo, F.; Armstrong, J. W.; Asmar, S. W. (2014-04-04). "The Gravity Field and Interior Structure of Enceladus". Science. 344 (6179): 78–80. doi:10.1126/science.1250551. ISSN 0036-8075.
- Dunaeva, A. N.; Kronrod, V. A.; Kuskov, O. L. (2016). "Physico-chemical models of the internal structure of partially differentiated Titan". Geochemistry International. 54 (1): 27–47. doi:10.1134/s0016702916010043. ISSN 0016-7029.
- "Possibility of Life on Europa". web.archive.org. 2007-06-09. Retrieved 2020-09-12.
- Bibring, Jean-Pierre; Langevin, Yves; Poulet, François; Gendrin, Aline; Gondet, Brigitte; Berthé, Michel; Soufflot, Alain; Drossart, Pierre; Combes, Michel (2004-04). "Perennial water ice identified in the south polar cap of Mars". Nature. 428 (6983): 627–630. doi:10.1038/nature02461. ISSN 0028-0836. Check date values in:
- SPIEGEL, DER. "Versteckt in Glasperlen: Auf dem Mond gibt es Wasser - DER SPIEGEL - Wissenschaft". www.spiegel.de (in German). Retrieved 2020-09-12.
- McCord, Thomas B. (2005). "Ceres: Evolution and current state". Journal of Geophysical Research. 110 (E5): E05009. doi:10.1029/2004JE002244. ISSN 0148-0227.
- Thomas, P. C.; Parker, J. Wm.; McFadden, L. A.; Russell, C. T.; Stern, S. A.; Sykes, M. V.; Young, E. F. (2005). "Differentiation of the asteroid Ceres as revealed by its shape". Nature. 437 (7056): 224–226. doi:10.1038/nature03938. ISSN 0028-0836.
- September 2005, Bjorn Carey 07. "Largest asteroid might contain more fresh water than Earth". Space.com. Retrieved 2020-09-12.
- Chang, Kenneth (2015-03-12). "Suddenly, it seems, water is everywhere in Solar System". The New York Times. ISSN 0362-4331. Retrieved 2020-09-12.
- Kuskov, O.L.; Kronrod, V.A. (2005). "Internal structure of Europa and Callisto". Icarus. 177 (2): 550–569. doi:10.1016/j.icarus.2005.04.014.
- Showman, A. P. (1999-10-01). "The Galilean Satellites". Science. 286 (5437): 77–84. doi:10.1126/science.286.5437.77.
- The solar system : exploring the planets and their moons from Mercury to Pluto and beyond. Sparrow, Giles, 1970-. San Diego, Calif.: Thunder Bay Press. 2006. ISBN 1-59223-579-4. OCLC 70170307.CS1 maint: others (link)
- Tobie, Gabriel; Grasset, Olivier; Lunine, Jonathan I.; Mocquet, Antoine; Sotin, Christophe (2005). "Titan's internal structure inferred from a coupled thermal-orbital model". Icarus. 175 (2): 496–502. doi:10.1016/j.icarus.2004.12.007.
- Verbiscer, A.; French, R.; Showalter, M.; Helfenstein, P. (2007-02-09). "Enceladus: Cosmic Graffiti Artist Caught in the Act". Science. 315 (5813): 815–815. doi:10.1126/science.1134681. ISSN 0036-8075.
- Gibb, E.L.; Mumma, M.J.; Dello Russo, N.; DiSanti, M.A.; Magee-Sauer, K. (2003). "Methane in Oort cloud comets". Icarus. 165 (2): 391–406. doi:10.1016/S0019-1035(03)00201-X.
- Vienna Standard Mean Ocean Water (VSMOW), used for calibration, melts at 273.1500089(10) K (0.000089(10) °C, and boils at 373.1339 K (99.9839 °C). Other isotopic compositions melt or boil at slightly different temperatures.
- A commonly quoted value of 15.7 used mainly in organic chemistry for the pKa of water is incorrect.
|Wikimedia Commons has media related to Water.|
- Water Citizendium