How does entropy change in the following processes?
Explain.
(a) freezing of a liquid
(b) sublimation of a solid
(c) dissolving sugar in water
(d) condensation of vapour.

Explanation

(a) Freezing of a liquid results in decrease in randomness and disorder, hence entropy decreases, `DeltaS gt 0` .
(b) Sublimation of a solid converts it into vapour where the molecules or atoms are free to move randomly. Hence disorder increases accompanying increase in entropy,`DeltaS gt0`
(c) Dissolving sugar in water separates the molecules of sugar in the solution increasing disorder and entropy, `DeltaS gt 0`
(d) Condensation of vapour decreases the disorder and randomness, hence entropy,`DeltaS lt 0`