# Specific Heat Capacity

## Specific Heat Capacity

• If a system undergoes a change of temperature from T to T+ΔT during the transfer of ΔQ amount of heat then heat capacity c of the system is defined as the ratio of

$$c=\frac{\Delta Q}{\Delta T}$$
• Thus Heat capacity per unit mass of a substance is its specific heat capacity. $$c=\frac{\Delta Q}{m\Delta T}$$

where,
m - mass of the substance
ΔQ - Heat absorbed or rejected by the substance
ΔT - Change in Temperature

• Specific heat capacity depends on the nature of substance.
• It is constant characteristics of the substance and is independent of the amount of substance.
• It also depends on the temperature of the substance
• Its unit is J Kg-1 K-1
• If the amount of substance is specified in terms of numbers of moles n instead of mass m then the heat capacity per mole of the substance is

$$=\frac{\Delta Q}{n\Delta T}$$

and is known as Molar Specific Heat capacity.

• It is constant characteristics of the substance and independent of the amount of substance
• It depends on the nature of the substance ,temperature and amount of heat supplied
• Its unit is J mol-1 K-1
• In case of gases , when a gas is heated, ordinarily there is change in volume as well as pressure in addition to change in temperature
• For simplicity either volume or pressure can be kept constant.Thus gas have two specific heat capacities
1) Specific heat capacity at constant volume CV
2) Specific heat capacity at constant pressure CP