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
CI = 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, CI = m x C.
An iron ball requires 5000 J heat energy to raise its temperature by 20ºC. Calculate the heat capacity of the iron ball.
Given, Q 5000 J, ΔT 20ºC or 20 K
Heat Capacity C = Heat energy required, Q / Rise in temperature, T
= 250 JK-1