Question

Define the term specific latent heat of fusion of ice. State its S.I. unit.

Answer 1

Hint: When heat is given to ice it converts into water and ideally when the same amount of heat is taken from water we can convert it back to ice. Latent heat of fusion deals with this particular property and during this process temperature doesn’t change or we can call it as an isothermal process.

Complete step by step answer:
It's a natural process that if one substance is heated then obviously its temperature rises. For example consider water heated on a gas stove, its temperature rises after some time due to heat. But incase of phase change from ice to water it doesn’t happen. The amount of energy taken will be used to break attractive bonds between molecules of ice instead of increasing its kinetic energy i.e during phase change kinetic energy remains constant while potential energy changes.
Now, coming to latent heat of fusion, It is the amount of heat taken in converting ice to water or the amount of heat given out when water is converted into ice
Specific latent heat of fusion of ice is nothing but the amount of heat required to convert 1kg of ice into water or amount of heat released when 1kg of water is converted into ice is called specific latent heat of fusion
SI unit of heat is joule
SI unit of mass is kg
So, SI unit of specific latent heat of fusion will be joule/kg

Note:
In case of calorimetry problems one usually confuses between latent heat and specific heat. Latent heat is the amount of heat taken which inturn causes phase change where temperature remains constant. But in case of specific heat phase remains constant while temperature changes.
Latent heat of fusion of ice = 80calories/g = 333.55 kilojoules/kg
Latent heat of vaporization of water = 540calories/g = 233 kilojoules/kg