Question

When \( \Delta H_{\text{vap}} = 30 \, \text{kJ/mol} \) and \( \Delta S_{\text{vap}} = 75 \, \text{J mol}^{-1} \text{K}^{-1} \), then the temperature of vapour, at one atmosphere, is \( \dots \dots \dots \, \text{K} \).

Answer 1

Correct Answer: 400

Using the relation at equilibrium:
$\Delta G = \Delta H - T\Delta S = 0$
Rearranging for $T$:
$T = \frac{\Delta H}{\Delta S}$
Substitute the given values:
$\Delta H_\text{vap} = 30 \, \text{kJ/mol} = 30 \times 10^3 \, \text{J/mol}$, $\Delta S_\text{vap} = 75 \, \text{J mol}^{-1} \text{K}^{-1}$
$T = \frac{30 \times 10^3}{75} = 400 \, \text{K}$
Final Answer: (400)