Chemistry – Physical chemistry | e-Consult

(a) Le Chatelier's principle states that if a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress.

(b) Adding carbon dioxide to the system will shift the equilibrium to the *left*. This is because carbon dioxide is a reactant in the reverse reaction (C₂H₆(g) ⇌ C₂H₄(g)). Adding a reactant will cause the equilibrium to shift towards the product side to consume the added reactant and re-establish equilibrium.

(c) ΔG° = -RTlnK_p = -(8.314 J/mol·K)(300 K)ln(0.75) = -249.4 J/mol ≈ -0.25 kJ/mol