Question

question 24 of 27
for a phase change, $delta h^{0}=2 kj/mol$ and $delta s^{0}=0.017 kj/(kcdot mol)$. what are $delta g$ and the spontaneity of the phase change at 500 k?
a. $delta g = - 6.5 kj$; nonspontaneous
b. $delta g=-6.5 kj$; spontaneous
c. $delta g = 10.5 kj$; spontaneous
d. $delta g = 10.5 kj$; nonspontaneous

Explanation:

Step1: Recall Gibbs - free energy formula

The formula for Gibbs - free energy is $\Delta G=\Delta H - T\Delta S$.

Step2: Substitute given values

We are given $\Delta H = 2\ kJ/mol$, $T = 500\ K$, and $\Delta S=0.017\ kJ/(K\cdot mol)$. Substitute these values into the formula: $\Delta G=2 - 500\times0.017$.

Step3: Calculate $\Delta G$

$\Delta G=2-8.5=- 6.5\ kJ/mol$.

Step4: Determine spontaneity

If $\Delta G<0$, the process is spontaneous. Since $\Delta G=-6.5\ kJ/mol < 0$, the phase - change is spontaneous.

Answer:

B. $\Delta G=-6.5\ kJ$; spontaneous