WaterH₂O

H2O • 18.015 g·mol⁻¹

molecularcovalentliquidCAS 7732-18-5PubChem 962 →
H₂OH2O18.0150 g·mol⁻¹
Molar mass18.015 g·mol⁻¹calc 18.015 • Atomic weights: CIAAW 2021 (conventional atomic weights)
FormulaH₂OH2O
Classmolecular • covalentliquid
Composition — H₂O
ElementCountMass (g/mol)Mass %
H22.01611.19%
O115.99988.81%

Physical properties

State at STP
liquid
Density
0.997 g·cm⁻³ (liquid at 25 °C, 1 atm)
Melting point
273.15 K (1 atm)
Boiling point
373.15 K (1 atm)

Structure & bonding

Bent molecule with two O-H covalent bonds and two lone pairs on oxygen. Hydrogen bonding gives high boiling point.

Occurrence & preparation

Abundant as liquid water covering ~71% of Earth.

Uses

  • Solvent
  • Drinking water
  • Industrial coolant

Safety

Non-toxic as pure water but can cause scalds as steam.

Consult current SDS. — consult current SDS before handling.

Constituent elements

Related reactions

POPULAR SEARCHES

Start typing to search

Search lessons, formulas, calculators, glossary, and elements. Try “pH”, “stoichiometry”, or “molar mass”.

Open full search →