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H2O

Water (H
2O)
The water molecule has this basic geometric structure
Ball-and-stick model of a water molecule
Space filling model of a water molecule
A drop of water falling towards water in a glass
Names
IUPAC name
water, oxidane
Other names
Hydrogen oxide, Dihydrogen monoxide (DHMO), Hydrogen monoxide, Dihydrogen oxide, Hydrogen hydroxide (HH or HOH), Hydric acid, Hydrohydroxic acid, Hydroxic acid, Hydrol, μ-Oxido dihydrogen
Identifiers
3D model (Jmol)
3587155
ChEBI
ChemSpider
117
PubChem CID
RTECS number ZC0110000
UNII
Properties
H
2O
Molar mass 18.01528(33) g/mol
Appearance White solid or almost colorless, transparent, with a slight hint of blue, crystalline solid or liquid
Odor None
Density Liquid:
0.9998396 g/mL at 0 °C
0.9970474 g/mL at 25 °C
0.961893 g/mL at 95 °C

Solid:
917 kg/m3 = 0.917 tonne/m3 = 0.917 kg/l = 0.917 g/cm3 ≈ 57.2 lb/ft3
Melting point 0.00 °C (32.00 °F; 273.15 K)
Boiling point 99.98 °C; 211.96 °F; 373.13 K
Solubility Poorly soluble in haloalkanes, aliphatic and aromatic hydrocarbons, ethers. Improved solubility in carboxylates, alcohols, ketones, amines. Miscible with methanol, ethanol, isopropanol, acetone, glycerol.
Vapor pressure 3.1690 kilopascals or 0.031276 atm (at 25 °C)
Acidity (pKa) 13.995
Basicity (pKb) 13.995
Thermal conductivity 0.6065 W/m·K
1.3330 (20°C)
Viscosity 0.890 cP
Structure
Hexagonal
C2v
Bent
1.8546 D
Thermochemistry
75.375 ± 0.05 J/mol·K
69.95 ± 0.03 J/mol·K
-285.83 ± 0.040 kJ/mol
-237.24 kJ/mol
Hazards
Main hazards Drowning
Water intoxication
Avalanche (as snow)
(see also Dihydrogen monoxide hoax)
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chloride Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other cations
Hydrogen sulfide
Hydrogen selenide
Hydrogen telluride
Hydrogen polonide
Hydrogen peroxide
Related solvents
Acetone
Methanol
Related compounds
 Water vapor
Ice
Heavy water
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Water (H
2O) is a polar inorganic compound that is at room temperature a tasteless and odorless liquid, nearly colorless with a hint of blue. This simplest hydrogen chalcogenide is by far the most studied chemical compound and is described as the "universal solvent" for its ability to dissolve many substances. This allows it to be the "solvent of life". It is the only common substance to exist as a solid, liquid, and gas in nature.

Water molecules form hydrogen bonds with each other and are strongly polar. This polarity allows it to separate ions in salts and strongly bond to other polar substances such as alcohols and acids, thus dissolving them. Its hydrogen bonding causes its many unique properties, such as having a solid form less dense than its liquid form, a relatively high boiling point of 100 °C for its molar mass, and a high heat capacity.

Water is amphoteric, meaning it is both an acid and a base—it produces H+
 and OH−
 ions by self ionization. This regulates the concentrations of H+
 and OH−
 ions in water.


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