Heat capacity
Heat capacity or thermal capacity is the ability of an object to store heat. It is abbreviated to Cth, and its SI unit is J/K (joule per kelvin). The concept is further discussed in the article on temperature.
Heat capacity is related to thermal capacitance by the formula
or, more simply,
where
- V = volume (m3)
- ρ = density (kg/m3)
- cp = specific heat (J/kgK) at constant pressure
- m = mass (kg)
The product ρc
p is known as
volumetric heat capacity,
thermal capacitance or (confusingly)
thermal capacity, and has units of J/m
3·K.
Dulong and
Petit predicted in
1818 that ρc
p would be constant for all solids (the
Dulong-Petit law). In fact, the quantity varies from about 1.2 to 4.5 J/m
3K. For fluids it is in the range 1.3 to 1.9, and for gases it is a constant 0.001 J/m
3K.