Heat capacity or Thermal capacity

Heat capacity or Thermal capacity

Now, you are familiar with specific heat capacity. It is the heat required to raise the temperature of a unit mass of the body by 10C. But, heat capacity is the heat required to raise the temperature of a entire mass of the body by 1˚C. Thus, heat capacity or thermal capacity is defined as the amount of heat energy required to raise the temperature of a body by 10C. It is denoted by C’.

Heat Capacity = Quantity of heat required / Rise in temperature

C^I  = Q/t

SI unit of heat capacity is J/K. It is also expressed in cal/˚C, kcal/˚C or J/˚C.

As we saw earlier, if C is the heat required to raise the temperature of unit mass of the body by 1˚C then the heat required to raise the temperature of ‘m’ mass of the substance is m C. So, heat capacity is also given as, C^I = m x C.

Exercise 1.5

An iron ball requires 5000 J heat energy to raise its temperature by 20ºC. Calculate the heat capacity of the iron ball.

Solution:

Given, Q 5000 J, ΔT 20ºC or 20 K

Heat Capacity C = Heat energy required, Q / Rise in temperature, T

 = 5000/20

= 250 JK^-1