For a phase transition process (such as the conversion of liquid water to steam) occurring at a constant temperature, the change in entropy ($\Delta S$) is related to the enthalpy change of the transition ($\Delta H$) and the absolute temperature ($T$) by the equation: $\Delta S = \frac{\Delta H}{T}$

Given data: Enthalpy change, $\Delta H = 30 \text{ kJ mol}^{-1} = 30000 \text{ J mol}^{-1}$ Temperature, $T = 27^{\circ}\text{C} = 27 + 273 \text{ K} = 300 \text{ K}$

Substituting the values into the formula: $\Delta S = \frac{30000 \text{ J mol}^{-1}}{300 \text{ K}}$ $\Delta S = 100 \text{ J mol}^{-1}\text{ K}^{-1}$ .