Gibbs Equation at Equilibrium

The Gibbs equation at equilibrium is an important concept in thermodynamics that relates the change in Gibbs free energy (ΔG) to the change in enthalpy (ΔH) and entropy (ΔS) of a system. It is given by the equation:

ΔG = ΔH - TΔS

Where:
- ΔG is the change in Gibbs free energy
- ΔH is the change in enthalpy
- T is the temperature in Kelvin
- ΔS is the change in entropy

Understanding the Value of G at Equilibrium

At equilibrium, the reaction is in a state of balance where the forward and reverse reactions occur at the same rate. This means that there is no net change in the concentration of reactants and products over time. In terms of the Gibbs equation, this implies that ΔG = 0.

Explanation of the Correct Answer

The correct answer to the question is '0', indicating that at equilibrium, the value of G is zero. This can be explained by considering the conditions at equilibrium:

1. ΔG = 0:
- At equilibrium, the system is in a state of minimum free energy.
- ΔG represents the driving force for a reaction. If ΔG is negative, the reaction is spontaneous in the forward direction. If ΔG is positive, the reaction is spontaneous in the reverse direction. At equilibrium, the reaction has no driving force, hence ΔG = 0.

2. No net change in reactants and products:
- At equilibrium, the forward and reverse reactions occur at the same rate.
- The concentrations of reactants and products remain constant over time.
- This indicates that the system has reached a balance where the rate of the forward reaction is equal to the rate of the reverse reaction.

3. Balance between ΔH and TΔS:
- The equilibrium condition is achieved when the enthalpy change (ΔH) and the temperature-dependent entropy change (TΔS) counterbalance each other.
- ΔH represents the heat absorbed or released during a reaction, while TΔS represents the entropy change.
- The equilibrium constant (K) is related to ΔG through the equation ΔG = -RTln(K), where R is the gas constant and T is the temperature in Kelvin.
- When ΔG = 0, ln(K) = 0, which implies that K = 1. This indicates that the concentrations of reactants and products are equal at equilibrium.

In conclusion, at equilibrium, the value of G is zero. This signifies a state of balance where the forward and reverse reactions occur at the same rate and there is no net change in the concentrations of reactants and products over time.