Back to Compound Library

Water (H₂O) — Properties, Uses & Safety

🏠 Everyday & Household

Overview

The most abundant compound on Earth's surface, essential for all known life.

IUPAC Name: oxidane
CAS Number: 7732-18-5
PubChem CID: 962
Molecular Formula: H₂O
Molar Mass: 18.02 g/mol
State at STP: liquid
Appearance: Colorless, odorless liquid

Physical Properties

Melting Point: 0 °C
Boiling Point: 100 °C
Density: 0.997 g/cm³
Specific Heat: 4.184 J/(g·K)
ΔH°f: -285.83 kJ/mol
ΔG°f: -237.13 kJ/mol
S°: 69.91 J/(mol·K)

Composition

Element	Count	Mass %
H	2	11.19%
O	1	88.81%

Bonding

Bond Type	Count	Between
single	2	O-H

Reactions

Electrolysis of water

2 H2O → 2 H2 + O2

decomposition

Acid-base neutralization

HCl + NaOH → NaCl + H2O

neutralization

Explore Water in 3D

Interact with the 3D molecular structure, run virtual experiments, and learn with our AI chemistry tutor in MyChemLab AI.

Open in MyChemLab AI