The latent heat of vaporisation of a substance is always
The latent heat of vaporisation of a substance is always
greater than its latent heat of fusion
greater than its latent heat of sublimation
equal to its latent heat of sublimation
less than its latent heat of fusion
Solution
Latent heat of vaporisation
- The latent heat of vaporisation is the heat energy required to change 1 kg of the material in its liquid state at its boiling point to \(\mathrm{1 ~ k g}\) of the material in its gaseous state.
- It is also the amount of heat energy released when 1 kg of vapour changes into 1 kg of liquid.
- For water at its normal boiling point or condensation temperature \(\left(100^{\circ} \mathrm{C}\right)\), the latent heat of vaporisation (latent heat of steam)
Latent heat of fusion
- The latent heat of fusion is the heat energy required to change \(\mathrm{1 ~ k g}\) of the material in its solid state at its melting point to 1 kg of the material in its liquid state.
- It is also the amount of heat energy released when at melting point 1 kg of liquid changes to 1 kg of solid.
- For water at its normal freezing temperature or melting point \(\left(0^{\circ} \mathrm{C}\right)\), the latent heat of fusion (or latent heat of ice) is
EXPLANATION:
- Latent heat of vaporisation is more than the latent heat of fusion.
- This is because when a substance gets converted from liquid to vapour, there is a large increase in volume.
- Hence more amount of heat is required But when a solid gets converted to a liquid, then the increase in volume is negligible.
- Hence very less amount of heat is required. So, latent heat of vaporisation is more than the latent heat of fusion.
- Hence option 1 is correct.
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