Heat capacity

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Physical size
Surname Heat capacity
Formula symbol
Size and
unit system
unit dimension
SI J · K −1 L 2 · M · T −2 · Θ −1

The heat capacity of a body is the ratio of the heat supplied to it ( ) to the resulting temperature increase ( ):

The unit of heat capacity is J / K .

In the case of homogeneous bodies, the heat capacity can be calculated as the product of the specific heat capacity and the mass of the body,

or as a product of its molar heat capacity and its amount of substance :

Both the specific and the molar heat capacity are material constants and are tabulated in relevant reference works.

The heat capacity is an extensive state variable , so it can be calculated for a body that is composed of parts as the sum of the respective heat capacities of its parts. The following therefore results for the total heat capacity :

For layer systems such as B. wall constructions , the heat capacity per unit area is given in J / (m 2 · K), for yard goods such as. B. extruded heat sinks per unit length , in J / (m · K).

Determination of the heat capacity in the mixing test

The experimental determination of the heat capacity of a body shows how to deal with this quantity:

The body is first placed in boiling water ( ) until it has reached this temperature itself. Then you transfer it to a calorimeter in which there is water at the temperature of . A mixing temperature of .

So the water has warmed up.

With the known specific heat capacity of water ( ), the heat absorbed by the water is calculated


The body has given off this amount of heat to the water when it cools down , so it is . Hence the heat capacity of the body is: