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

FREE Expert Solution

We're being asked to determine the K or equilibrium constant for a reaction with ΔG° (standard free energy) for the reaction:

N2(g)+3H2(g)⇌2NH3(g)

We can use the following equation to solve for ΔG˚rxn:


ΔG°rxn=ΔG°f, prod-ΔG°f, react


Note that we need to multiply each ΔG˚f by the stoichiometric coefficient since ΔG˚f is in kJ/mol. 


ΔG°rxn=(2 mol NH3)(-16.4 kJ1 mol NH3)                   -(2 mol N2)(0 kJ1 mol N2 )+(3 mol H2)(0 kJ1 mol H2 )


ΔG˚rxn = –32.8 kJ


Now use the ΔG°-K equation where:

G = -RTln(K)

where ΔG is the free energy in J/mol K; 

R is the gas constant (8.314 J/molK); 

T is temperature in K; 

and as equilibrium constant

Given are:

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Problem Details

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

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