Water is a chemical substance with the chemical formula H2O. A water mol molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near hydrophilic surfaces. Under nomenclature used to name chemical compounds, Dihydrogen monoxide is the scientific name for water, though it is almost never used.
Water covers 70.9% of the Earth's surface, and is vital for all known forms of life. On Earth, 96.5% of the planet's water is found in oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Only 2.5% of the Earth's water is freshwater, and 98.8% of that water is in ice and groundwater. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth's freshwater (0.003%) is contained within biological bodies and manufactured products.
Water (H2O)
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Water
Oxidane | |
Other names
Hydrogen oxide
Dihydrogen monoxide
Hydrogen monoxide Dihydrogen oxide Hydrogen hydroxide | |
Identifiers
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ZC0110000
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Properties
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H2O
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18.01528(33) g/mol
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Appearance
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white solid or almost colorless, transparent, with a slight hint of blue, crystalline solid or liquid
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1000 kg/m3, liquid (4 °C) (62.4 lb/cu. ft)
917 kg/m3, solid | |
99.98 °C, 211.97 °F (373.13 K)
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15.74
~35–36 | |
15.74
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1.3330
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0.001 Pa s at 20 °C
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Structure
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Hazards
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NFPA 704
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