Question

What is the difference between delta G at equilibrium and delta G at steady state?

Do reactions at equilibrium have any available energy to do useful work? Do reactions at steady state have available energy to do useful work?

What requirement must be met to sustain a reaction at steady state?

Answer 1

at equilibrium. The Gibb's free energy is a measure of the incompleteness of a reaction. The more difference between the Gibb's free energy an standard Gibb's free energy in a reaction, the more incomplete is the reaction.

The standrd Gibbs free energy at equilibrium is given by -RT ln Kp ​​​​​​, where K​​​​​​p is the equilibrium constant at constan pressure.

In Steady state, we have two or more equilibrium taking place at a constant rate which doesnt change the concentration of a particular intermediate. We have the change in concentration of the intermediate as zero with respect to time. The Gibb's free energy is not zero in this approximation.

Reactions at equilibrium do not have any available energy to do any work, but reactions in steady state do.

If we perturb(disturb) a system in equilibrium, the system would return to its equilibrium with a different K​​​​​​p, yielding a different Standard Gibb's free energy according to that condition. But if we perturb a system which is in steady state, the Gibbs free energy changes, that is energy available to do any type of work also changes.