The enthalpy of fusion for benzene, C₆H₆, is 127.34 kJ/kg, and its melting point is 5.49 $\degree$C.Estimate $\Delta$G $\degree$ when 1.00 mole of benzene melts at 25.00 $\degree$C.

Question

Quizplus · Accepted Answer

The change in Gibbs free energy ($\Delta G$) for a process at constant temperature and pressure can be calculated using the equation $\Delta G = \Delta H - T\Delta S$, where $\Delta H$ is the enthalpy change, $T$ is the temperature in Kelvin, and $\Delta S$ is the entropy change. For the melting of benzene, $\Delta H$ is given as the enthalpy of fusion, and $\Delta S$ can be calculated from $\Delta H$ and the melting point. Since the melting point is given in Celsius and the process occurs at 25.00°C, we first convert the temperature to Kelvin (298.15 K) and then use the given enthalpy of fusion (127.34 kJ/kg) and the molar mass of benzene (78.11 g/mol) to find $\Delta S$ and subsequently $\Delta G$. The calculation shows a decrease in Gibbs free energy, indicating the process is spontaneous at 25.00°C, but the exact numerical value matches the choice (B).

The Enthalpy of Fusion for Benzene, C6H6, Is 127 °\degree° CEstimate Δ\DeltaΔ

The Enthalpy of Fusion for Benzene, C₆H₆, Is 127 $\degree$ CEstimate $\Delta$