25 December 2017

Specific heat and latent heat

What is the specific heat?

Specific heat is the amount of heat required to raise a unit mass of the substance through a unit rises in temperature. 

The symbol c will be used for specific heat. 

C = Q / m * Δt J / kg k 

Q = The amount of heat transfer ( J )
m = Mass of the substance ( kg )
Δt = The rise in temperature ( K ) 

Since heat is not a property, so the specific heat is qualified with the process through which exchange of heat is made. 

The product of mass and specific heat ( mc ) is called the heat capacity of the substance. 

For gases, 
If the process is at constant pressure ( cp ).
If the process is at constant volume ( cv ).

For solids and liquids, 

The specific heat does not depend on the process. 

What is latent heat?

The amount of heat required to cause a phase change in a unit mass of a substance at constant pressure and temperature.

There are three phases in which matter can exist: solid, liquid, and vapour or gas.

The latent heat of fusion is the amount of heat transferred to melt a unit mass of solid into a liquid. 


to freeze unit mass of liquid to solid. 

The latent heat of vaporization is the quantity of heat required to vaporize unit mass of liquid into vapour. 


to condense unit mass of vapour into liquid. 

The latent heat of sublimation is the amount of heat transferred to convert unit mass of solid to vapour.