Question

What entropy change is associated with the reversible phase change from 1.0kg of ice to water at 0 ° C?

Answer 1

Answer:

1200 J/K  

Explanation:

The formula for the entropy associated with a reversible phase change is

$\Delta S= \dfrac{q_{\text{rev}}}{T}$

1. Calculate q

For a reversible phase change like melting,

$q_{\text{rev}} = m\Delta_{\text{fus}}H = \text{1000 g} \times \dfrac{\text{334 J}}{\text{1 g}} = \text{334 000 J}$

2. Calculate ΔS

$\Delta S = \dfrac{q_{\text{rev}}}{T} =\dfrac{\text{334 000 J}}{\text{273.15 K}} = \textbf{1200 J/K}$