Water Thermal Properties – Density, Heat Capacity, and Conductivity

Comprehensive thermodynamic properties of water including density, specific heat capacity, thermal conductivity, and other critical properties at varying temperatures and pressures.

Property	Value (SI)	Value (Imperial)	Notes
Boiling Temperature (at 101.325 kPa)	99.974 °C	211.953 °F	Standard atmospheric pressure
Bulk Modulus Elasticity	2.15×10⁹ Pa	2.15×10⁹ N/m²	Elasticity property
Critical Temperature	373.946 °C	705.103 °F	Critical point
Critical Pressure	22.06 MPa	217.7 atm / 3200 psi	Critical point pressure
Critical Density	0.322 g/cm³	20.1018 lbm/ft³	At critical point
Ionization Constant pKw (at 25°C)	13.995	13.995	pH indicator
Latent Heat of Melting	334 kJ/kg	144 Btu(IT)/lb	Solid to liquid transition
Latent Heat of Evaporation (at 100°C)	2256 kJ/kg	970 Btu(IT)/lb	Liquid to gas transition
Maximum Density (at 4°C)	999.975 kg/m³	8.34519 lbm/gal(US)	Highest density point
Melting Temperature (at 101.325 kPa)	0 °C	32 °F	Ice to water transition
Molar Mass	18.01527 g/mol	18.01527 g/mol	Molecular weight
pH (at 25°C)	6.9976	6.9976	Neutral water
Specific Heat Capacity - Liquid (at 15°C)	4.187 kJ/kg·K	1.001 Btu(IT)/(lbm·°F)	Heat capacity of liquid water
Specific Heat Capacity - Ice	2.108 kJ/kg·K	0.5035 Btu(IT)/(lbm·°F)	Heat capacity of solid water
Specific Heat Capacity - Water Vapor	1.996 kJ/kg·K	0.4767 Btu(IT)/(lbm·°F)	Heat capacity of gaseous water
Specific Weight (at 4°C)	9.806 kN/m³	62.43 lbf/ft³	Force per unit volume
Thermal Expansion (4°C to 100°C)	4.2×10⁻⁴	4.2×10⁻⁴	Non-linear with temperature
Triple Point Pressure	611.657 Pa	0.00604 atm / 0.08871 psi	Triple point condition
Triple Point Temperature	0.01 °C	32.02 °F	Solid-liquid-gas equilibrium