Heat Capacity - Extensive and Intensive Quantities

Extensive and Intensive Quantities

An object's heat capacity (symbol C) is defined as the ratio of the amount of heat energy transferred to an object to the resulting increase in temperature of the object,

In the International System of Units, heat capacity has the unit joules per kelvin.

Heat capacity is an extensive property, meaning it is a physical property that scales with the size of a physical system. A sample containing twice the amount of substance as another sample requires the transfer of twice the amount of heat to achieve the same change in temperature .

For many experimental and theoretical purposes it is more convenient to report heat capacity as an intensive property - an intrinsic characteristic of a particular substance. This is most often accomplished by expressing the property in relation to a unit of mass. In science and engineering, such properties are often prefixed with the term specific. International standards now recommend that specific heat capacity always refer to division by mass. The units for the specific heat capacity are .

In chemistry, heat capacity is often specified relative to one mole, the unit of amount of substance, and is called the molar heat capacity. It has the unit .

For some considerations it is useful to specify the volume-specific heat capacity, commonly called volumetric heat capacity, which is the heat capacity per unit volume and has SI units . This is used almost exclusively for liquids and solids, since for gases it may be confused with specific heat capacity at constant volume.