In a crystal, at , one out of lattice site is found to be vacant but at , one out of lattice sites i — Solid State Chemistry Question

💡 Solution & Explanation

Using $f = \exp(-\Delta H / RT)$, $\ln(f_2 / f_1) = \frac{\Delta H}{R} (\frac{1}{T_1} - \frac{1}{T_2})$. $\ln(5) = \frac{\Delta H}{8.314} (\frac{1}{1100} - \frac{1}{1200})$. $1.609 = \frac{\Delta H}{8.314} (\frac{100}{1320000})$. $\Delta H = 1.609 \times 8.314 \times 13200 \approx 176500 \text{ J/mol} = 176.5 \text{ kJ/mol}$, closest to 176.8. Therefore, correct answer is B.