Question

For a certain reaction $\Delta H = -225$ kJ and $\Delta S = -150$ J K$^{-1}$. Find the temperature so that $\Delta G$ is zero.

• A. 1500 K
• B. 1450 K
• C. 1340 K
• D. 1300 K

Hint:

Always ensure $\Delta H$ and $\Delta S$ are in the same units (usually Joules) before dividing.

Answer 1

The Correct Option is A

Step 1: Formula
Gibbs free energy equation: $\Delta G = \Delta H - T\Delta S$.

Step 2: Analysis
For $\Delta G = 0$: $T = \frac{\Delta H}{\Delta S}$.

Step 3: Calculation
$\Delta H = -225$ kJ = $-225,000$ J.
$\Delta S = -150$ J/K.
$T = \frac{-225,000}{-150} = \frac{22500}{15} = 1500$ K.

Step 4: Conclusion
The temperature is 1500 K.
Final Answer: (A)