Gibbs Free Energy Video Lessons

Concept

# Problem: Part A. 2Ca(s)+O2(g) → 2CaO(s)  ΔH°rxn= -1269.8 kJ; ΔS°rxn= -364.6 J/K. Calculate the free energy change for the reaction at 24 °C.Part B. Calculate ΔS°rxn for the balanced chemical equation: H2S(g)+2 O2(g)→H2O(g)+SO2(g)Part C. 2 CO(g)+2 NO(g)→2 CO2(g)+N2(g). Use standard free energies of formation to determine ΔG°rxn for this reaction at 25°C.Part D. Use data from Appendix IIB to calculate the equilibrium constants at 25 °C for this reaction: N2(g)+3 H2(g)⇌2 NH3(g)

###### FREE Expert Solution

Recall the following equations to solve the questions:

For part A:

2Ca(s)+O2(g) → 2CaO(s)

We are given:

ΔH°rxn= -1269.8 kJ;

ΔS°rxn=  = 0.3646 kJ/K

T = 24 °C + 273.15 = 297.15 K

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###### Problem Details

Part A. 2Ca(s)+O2(g) → 2CaO(s)  ΔH°rxn= -1269.8 kJ; ΔS°rxn= -364.6 J/K.

Calculate the free energy change for the reaction at 24 °C.

Part B. Calculate ΔS°rxn for the balanced chemical equation: H2S(g)+2 O2(g)→H2O(g)+SO2(g)

Part C. 2 CO(g)+2 NO(g)→2 CO2(g)+N2(g). Use standard free energies of formation to determine ΔG°rxn for this reaction at 25°C.

Part D. Use data from Appendix IIB to calculate the equilibrium constants at 25 °C for this reaction: N2(g)+3 H2(g)⇌2 NH3(g)