The specific heats of iodine vapours and solid are 0.031 and 0.055 cal/g, respectively. If the entha — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

Using Kirchhoff's equation: $\Delta H_2 = \Delta H_1 + \Delta C_P(T_2 - T_1)$. $\Delta C_P = C_P(\text{vapour}) - C_P(\text{solid}) = 0.031 - 0.055 = -0.024\text{ cal/g}^\circ\text{C}$. Thus, $\Delta H_2 = 24 + (-0.024)(250 - 200) = 24 - 1.2 = 22.8\text{ cal/g}$.