Problem: Use data from appendix iib in the textbook to calculate the equilibrium constants at 25°C for each of the following reaction:2 H2S (g) ⇌ 2 H2(g) + S2(g)

FREE Expert Solution

2 H2S (g) ⇌ 2 H2(g) + S2(g)


ΔG°rxn=-RTlnK


ΔG°rxn=ΔG°f, prod-ΔG°f, react


The values for ΔG˚f can be looked up in textbooks or online:

ΔG˚f, H2S(g) = –33.4 kJ/mol

ΔG˚f, H2(g) = 0 kJ/mol

ΔG˚f, S2(s) = 78.7 kJ/mol


Solving for ΔG˚rxn:


ΔG°rxn=ΔG°f, prod-ΔG°f, react


ΔG°rxn=0+(1 mol S2)(78.7 kJ1 mol S2)           -(2 mol H2S)-33.4 kJ1 mol H2S

ΔG˚rxn145.5 kJ/mol

ΔG°rxn=145.5 kJmol×103 J1 kJ

ΔG˚rxn145500 J/mol



We can now solve for the equilibrium constant using these given values:

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Problem Details

Use data from appendix iib in the textbook to calculate the equilibrium constants at 25°C for each of the following reaction:

2 H2S (g) ⇌ 2 H2(g) + S2(g)