Difference Between Heat capacity And Specific Heat For WAEC

Heat Capacity and Specific heat have some differences because they are not the same in definition and unit. 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.

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

E =mct

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

Read: Note on specific heat capacity

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)

C_p = E/t

C_p 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

C_p = mass x specific heat (c)

Differences