Specific heat capacity

Heating water on a steady burner: raising it by 40 °C takes about twice as long as raising the same water by 20 °C, and a 20 °C rise for double the mass also takes twice as long. Mustard oil of the same mass heats faster than water.

So the heat needed depends on the mass, the temperature rise and the substance. The heat capacity S = ΔQ/ΔT is the heat needed to raise a body's temperature by one unit.

Specific heat capacity s = (1/m)(ΔQ/ΔT), in J kg⁻¹ K⁻¹: the heat per unit mass per unit temperature rise. It depends on the substance and its temperature, not on the amount.

Specific heat capacity in J kg⁻¹ K⁻¹: aluminium 900.0, carbon 506.5, copper 386.4, lead 127.7, silver 236.1, tungsten 134.4, water 4186.0, ice 2060, glass 840, iron 450, kerosene 2118, edible oil 1965, mercury 140.

Molar specific heat capacity C = (1/μ)(ΔQ/ΔT), in J mol⁻¹ K⁻¹, uses moles instead of mass.

For a gas, the conditions under which heat is added matter. C_p is measured at constant pressure and C_v at constant volume; C_p is larger.

Molar values (J mol⁻¹ K⁻¹), C_p / C_v: He 20.8 / 12.5, H₂ 28.8 / 20.4, N₂ 29.1 / 20.8, O₂ 29.4 / 21.1, CO₂ 37.0 / 28.5.

Water has the highest specific heat among these substances. That is why it is used as the coolant in car radiators and in hot-water bags.

Because of water's large s, the sea warms and cools slowly compared with land. Coastal climates stay mild, while deserts heat up quickly by day and cool quickly at night.