Heat capacity (C) is the amount of heat (Q) required to raise the temperature(T) of a substance by a unit degree.
It is usually expressed in terms of J/K
Heat capacity is an intensive property i.e. it is not dependent on the amount of the substance. i.e, the amount of heat required to raise the temperature of 1 g of copper per kelvin would be the same as that corresponding to 100 g.
The heat capacity of a defined system is the amount of heat (usually expressed in calories, kilocalories, or joules) needed to raise the system's temperature by one degree (usually expressed in Celsius or Kelvin). It is expressed in units of thermal energy per degree temperature. To aid in the analysis of systems having certain specific dimensions, molar heat capacity and specific heat capacity can be used. To measure the heat capacity of a reaction, a calorimeter must be used. Bomb calorimeters are used for constant volume heat capacities, although a coffee-cup calorimeter is sufficient for a constant pressure heat capacity.