13. Specific latent heat

If $Q$ is the amount of heat energy absorbed or released by the ‘m' mass of a substance during its phase change at a constant temperature, then the specific latent heat is given by

 

 

As a result, specific latent heat is the amount of heat energy absorbed or liberated by a unit mass without causing a temperature change during a state change. J/kg is the SI unit for specific latent heat.

 

Let us look at the example problem.

 

1. How much heat energy is required to melt 4 kg of ice? (Specific latent heat of ice = 336 J/g)

  

Given:

 

Mass ($m$) $=$ $4 kg$

 

Specific latent heat of ice ($L$) $=$ $336 J/g$

 

To find: Heat energy ($Q$)