Question

What unit is used to measure latent heat?

Answer 1

Hint: Latent heat is referred to the heat which when supplied to a body brings about the change in state of the body. As the change in state is an equilibrium process, the latent heat is the only form of heat which when given to a body does not bring about a change in temperature of the body. We shall see its formula to find out the unit in which Latent heat is measured.

Complete answer:
Let us first assign some terms that we are going to use in our solution.
Let us consider a small amount of an object (say, water) which is undergoing phase transformation. Let the phase transformation be from ice to liquid water. Then, the amount of heat required to bring about this phase transformation is equal to:
$\Rightarrow Q=m{{L}_{fusion}}$
Where,
‘Q’ is the amount of heat supplied, that is, the latent heat supplied.
‘m’ is the mass of water which undergoes phase change. And,
‘${{L}_{fusion}}$’ is the latent heat of fusion of ice.
The standard definition of Latent heat from the above formula will be, the amount of heat energy required to change the phase of 1kg of a substance. Thus, its unit will be Joule per kilogram.
Hence, the unit that is used to measure latent heat of a substance is Joule per kilogram $\left( J{{g}^{-1}} \right)$.

Note:
The unit of any quantity be it force, momentum, acceleration, torque, mass, etc. is not a specific quantity. People around the globe use different unit systems. For example, the Europeans generally use the metric system while calculating mass of an object whereas the Americans use the CGS system. This is why a standard system was developed known as the SI system of units which is accepted all over the globe.