Heat Capacity and Specific heat have some differences because they are not the same in definition and unit. Although the two can be used to get the amount of energy needed to change the temperature of something and produce a change of state.
So, before we look at their differences, let’s look at the definition of the two.
What is Specific Heat
If we heat some material so that its temperature rises, the amount of energy we must supply depends on three things
- The mass m of the material we are heating
- The temperature change we wish to achieve
- The material itself
Some materials are easier to heat than others. It takes more energy to raise the temperature of 1kg of water by 1 oC than to raise the temperature of 1kg of alcohol by the same amount.
The amount of energy that must be supplied can be represented by
Where m is the mass, c is the specific heat capacity, t is the temperature change.
T = final temperature – initial temperature
Therefore, the specific heat capacity of a substance is defined as the energy required per unit mass of a substance to raise the temperature by 1k (or 1 oC)
The word specific there means ‘per unit mass’, i.e. per kg
The unit of specific heat capacity is JKg-1K-1
What is Heat Capacity
If we consider the quantity of heat required to raise the entire mass of a body by 1k instead of just 1kg of the mass, the heat involved is known as heat capacity or thermal capacity.
The heat capacity of a body is defined as the quantity of heat required to raise the temperature of a body by 1k.
The unit is Joule per kelvin (JK-1)
Cp = E/t
Cp is heat capacity
E is the amount of energy
T is the temperature change
There is a relationship between heat capacity and specific heat, and this can be shown in the expression below
Cp = mass x specific heat (c)
Differences Between Heat Capacity and Specific Heat
|Heat Capacity||Specific Heat|
|Energy required to raise the temperature of a body by 1k.||Energy required per unit mass of a substance to raise the temperature by 1k|
|The unit is JK-1||The unit is JKg-1K-1|
|Cp = E/t||C = E/mt|