Question

The entropy change can be calculated by using the expression $\Delta S=\frac{q_{rev}}{T}$.
When water freezes in a glass beaker, choose the correct statement amongst the following.
(a)$\Delta$S (system) decreases but $\Delta$ S (surroundings) remains the same
(b) $\Delta$S (system) increases but $\Delta$S (surroundings) decreases
(c) $\Delta$S (system) decreases but $\Delta$S (surroundings) increases
(d) $\Delta$S (system) decreases but $\Delta$S (surroundings) also decreases

Answer 1

(c)

The entropy change can be calculated by using the expression
$\Delta S=\frac{q_{rev}}{T}$
When water freezes in a glass beaker, $\Delta S$ (system) decreases because molecules in solid ice are less random than in liquid water. However, when water freezes to ice, heat is released which is absorbed by the surroundings,
Hence, entropy of the surrounding increases.