Use the free energies of formation given below to calculate the equilibrium constant (k) for the following reaction at 298 k. 2 hno3(aq) + no(g) → 3 no2(g) + h2o(l) k = ? δ g0f(kj/mol) -110.9 87.6 51.3 -237.1

The equilibrium constant K = 1.15*10^-9

Explanation:

Given:

ΔG°f(HNO3) = -110.9 kj/mol

ΔG°f(NO) = 87.6 kj/mol

ΔG°f(NO2) = 51.3 kj/mol

ΔG°f(HNO3) = -237.1 kj/mol

To determine:

The equilibrium constant (K) for the given reaction

Calculation:

The chemical reaction is:

The equation that relates the standard free energy change ΔG° to the equilibrium constant K is:

(or)

where R = gas constant = 8.314 J/mol-K

T = temperature in Kelvin

where n(p) and n(r) are the number of moles of the products and reactants respectively

Therefore for the given reaction:

Substituting the given values for ΔG°f:

ΔG° = + 51 kJ

Substituting the calculated ΔG° in equation (1) at T = 298 K gives: