The specific heats of iodine vapours and solid are 0.031 and 0.055 cal/g, respectively. If the enthalpy of sublimation of iodine is 24 cal/g at 200°C, then the enthalpy of sublimation of iodine at 250

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The specific heats of iodine vapours and solid are 0.031 and 0.055 cal/g, respectively. If the enthalpy of sublimation of iodine is 24 cal/g at 200°C, then the enthalpy of sublimation of iodine at 250°C should be

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The enthalpy change at 250 K, Δ H sub (250), can be calculated using the value at 200 K, and the heat capacities of the gaseous and solid phases. The formula is: Δ H sub (250) = ΔH 200 + [C P (g) - C P (s)]ΔT Given the values, we have: Δ H sub (250) = 24 + (0.031 - 0.055)(50) Δ H sub (250) = 24 + (-0.024)(50) Δ H sub (250) = 24 - 1.2 Δ H sub (250) = 22.8 cal/g This corresponds to option (b).

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