Question

Latent heat of fusion of ice is:
A. $336kJk{{g}^{-1}}$
B. $663kJk{{g}^{-1}}$
C. $363kJk{{g}^{-1}}$
D. $636kJk{{g}^{-1}}$

Answer 1

Hint: Recall the definition and value of latent heat of fusion for ice. The amount of heat energy absorbed or released when a solid changes into liquid at atmospheric pressure at its melting point, is known as the latent heat of fusion.

Complete step by step answer:

Latent heat is the hidden form of energy means the energy used to change its state without increasing its temperature. At atmospheric pressure the value of latent heat of ice is 80 cal/g.
As we know that,
1 calorie = 4.2 joule
So, for converting this latent heat in joule per gram (J/g) or kilojoule per kilogram (kJ/kg), we have to multiply it by 4.2 i.e.,
$\Rightarrow {{Q}_{L}}=80\times 4.2kJ/kg$
$\Rightarrow {{Q}_{L}}=336kJ/kg$
Hence, the correct option is A, i.e., $336kJk{{g}^{-1}}$

Additional Information:
The heat absorbed or released during phase change is known as latent heat. There is no temperature change, while one phase changes to another, thus there is no change in kinetic energy of the particles in the material. The energy released comes from the potential energy stored in the bonds in between the particles.

Note: Students should understand the concept of latent heat and need to memorize the value of latent heat of fusion for ice and some other values of this kind also. So that students can answer this type of questions quickly. Students should be very careful while dealing with units. Students also need to know the relation between calorie and joule so that they can use these both units i.e., calorie and joule interchangeably as per the demand of the question.