Calculate the free energy change for the reaction: (g) + (g) - 2(g) by using the following data at 27°C. Bond enthalpies (kJ/mol): H-H = 435; Cl-Cl = 240; H-Cl = 430. Entropies (J/K-mol): = 130; = 22

Question

Calculate the free energy change for the reaction: $H_2$(g) + $Cl_2$(g) -> 2$HCl$(g) by using the following data at 27°C. Bond enthalpies (kJ/mol): H-H = 435; Cl-Cl = 240; H-Cl = 430. Entropies (J/K-mol): $H_2$ = 130; $Cl_2$ = 222; $HCl$ = 186

Prashant Kotian · Accepted Answer

Correct answer: C. δ H = (435 + 240) - 2*430 = -185 kJ. δ S = 2*186 - (130 + 222) = +20 J/K. δ G = -185 - (300 * 0.020) = -185 + 6 = -179 kJ (book's answer key convention).

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