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Water

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Water
The water molecule has this basic geometric structure
The water molecule has this basic geometric structure
Ball-and-stick model of a water molecule
Ball-and-stick model of a water molecule
Space filling model of a water molecule
Space filling model of a water molecule
  Oxygen, O
  Hydrogen, H
A drop of water falling toward water in a glass
A drop of water falling toward water in a glass
Names
Preferred IUPAC name
Water
Systematic IUPAC name
Oxidane (not in common use)[1]
Other names
  • Hydrogen oxide
  • Hydrogen hydroxide (H2O or HOH)
  • Hydroxylic acid
  • Dihydrogen monoxide (DHMO) (parody name)[2]
  • Dihydrogen oxide
  • Hydric acid
  • Hydrohydroxic acid
  • Hydroxic acid
  • Hydroxoic acid
  • Hydrol[3]
  • μ-Oxidodihydrogen
  • κ1-Hydroxylhydrogen(0)
  • Aqua
  • Neutral liquid
  • Oxygen dihydride (may be considered incorrect)
Identifiers
3D model (JSmol)
3587155
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.028.902 Edit this at Wikidata
EC Number
  • 231-791-2
117
KEGG
RTECS number
  • ZC0110000
UNII
  • InChI=1S/H2O/h1H2 checkY
    Key: XLYOFNOQVPJJNP-UHFFFAOYSA-N checkY
  • O
Properties
H2O
Molar mass 18.015 g·mol−1
Appearance Almost colorless or white crystalline solid, almost colorless liquid, with a hint of blue, colorless gas[4]
Odor Odorless
Density
  • Liquid (1 atm, VSMOW):
  • 0.99984283(84) g/mL at 0 °C[5]
  • 0.99997495(84) g/mL at 3.983035(670) °C (temperature of maximum density, often 4 °C)[5]
  • 0.99704702(83) g/mL at 25 °C[5]
  • 0.96188791(96) g/mL at 95 °C[6]
  • Solid:
  • 0.9167 g/mL at 0 °C[7]
Melting point 0.00 °C (32.00 °F; 273.15 K) [a]
Boiling point 99.98 °C (211.96 °F; 373.13 K)[8][a]
Solubility Poorly soluble in haloalkanes, aliphatic and aromatic hydrocarbons, ethers.[9]
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 at 25 °C[10]
Acidity (pKa) 13.995[11][12][b]
Basicity (pKb) 13.995
Conjugate acid Hydronium H3O+ (pKa = 0)
Conjugate base Hydroxide OH– (pKb = 0)
Thermal conductivity 0.6065 W/(m·K)[15]
1.3330 (20 °C)[16]
Viscosity 0.890 mPa·s (0.890 cP)[17]
Structure
Hexagonal
C2v
Bent
1.8546 D[18]
Thermochemistry
75.385 ± 0.05 J/(mol·K)[8]
69.95 ± 0.03 J/(mol·K)[8]
−285.83 ± 0.04 kJ/mol[9][8]
−237.24 kJ/mol[9]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g. sodium chlorideFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
0
0
Flash point Non-flammable
Related compounds
Other anions
Related solvents
Supplementary data page
Water (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkYX markN ?)

Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless,[c] and nearly colorless chemical substance. It is the main constituent of Earth's streams, lakes, and oceans. Water is also the fluid of all known living organisms, in which it acts as a solvent. Water, being a polar molecule, undergoes strong intermolecular hydrogen bonding which is a large contributor to its physical and chemical properties.[19] It is vital for all known forms of life, despite not providing food energy or being an organic micronutrient. Due to its presence in all organisms, its chemical stability, its worldwide abundance, and its strong polarity relative to its small molecular size, water is often referred to as the "universal solvent".[20]

Because Earth's surface temperature and pressure is relatively close to water's