|
| Water (H2O) | |
|---|---|
 | |
 |  |
 | |
| IUPAC name | water, oxidane |
| Other names | Hydrogen hydroxide (HH or HOH), hydrogen oxide, dihydrogen monoxide (DHMO) (systematic name), hydrogen monoxide, dihydrogen oxide, hydric acid, hydrohydroxic acid, hydroxic acid, hydrol, μ-oxido dihydrogen, κ1-hydroxyl hydrogen(0) |
| Identifiers | |
| CAS number | |
| PubChem | |
| ChEBI | CHEBI:15377 |
| RTECS number | ZC0110000 |
| SMILES | O |
| Beilstein Reference | 3587155 |
| Gmelin Reference | 117 |
| Properties | |
| Molecular formula | H2O |
| Molar mass | 18.01528(33) g/mol |
| Appearance | White crystal-like solid, almost colorless liquid with a hint of blue, colorless gas |
| 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: 0.9167 g/ml at 0 °C |
| Melting point | 0.00 °C, 273 K, 32 °F |
| Boiling point | |
| Solubility in water | N/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 |
| Acidity (pKa) | 13.995 |
| Basicity (pKb) | 13.995 |
| Thermal conductivity | 0.6065 W/(m·K) |
| Refractive index (nD) | 1.3330 (20 °C) |
| Viscosity | 0.890 cP |
| Structure | |
| Crystal structure | Hexagonal |
| C2v | |
| Molecular shape | Bent |
| Dipole moment | 1.8546 D |
| Thermochemistry | |
| Std enthalpy of formation ΔfH | −285.83 ± 0.04 kJ/mol |
| Standard molar entropy S | 69.95 ± 0.03 J/(mol·K) |
| Specific heat capacity, C | 75.385 ± 0.05 J/(mol·K) |
| Hazards | |
| Main hazards | Drowning Avalanche (as snow)
|
| NFPA 704 |
0 0 0 |
| Flash point | Non-flammable |
| Related compounds | |
| Other cations | Hydrogen sulfide Hydrogen selenide Hydrogen telluride Hydrogen polonide Hydrogen peroxide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) | |
Water (H2O) is a transparent, tasteless, odourless, and almost colourless chemical substance and covers about 71% of Earth's surface.
No known life can live without it. Water is essential for life. This has to be qualified a bit. There are some forms of life which can survive without it, but cannot reproduce without it. Since reproduction is a central part of life, it is clear that water is essential for an organism to survive and reproduce.
 |
|
