Question

Why must the equilibrium always be a mixture of A, B and C in reaction A+B=C? (albeit shifted to product side for △G◦ < 0 and reactant side for △G◦ > 0)

Answer 1

Now = Final - Initial = Product - Reactant

Gibbs free energy always tends to be low so that it can be stable.

As a analogy Gibbs free energy can be compared to potential energy lesser it is more the stable a system is.

In a reversible reaction reaction will always proceeds in the direcction where gibbs free energy decreases.

Thus if

The reaction will proceeds in the direction from higher gibbs free energy to lower gibbs free energy, similar to that of potential energy e.g. if we drop a ball from a building it will go from higher potenial energy zone (top of building) to lower potential energy zone (ground).

Therfore for

............Forward reaction

............Backward reaction