For a chemical reaction, the free energy change `(DeltaG)` is negative. The reaction is

Options

A. A spontaneous reaction
B. An equilibrium reaction
C. A non - spontaneous reaction
D. Characherised by `r_(f)=r_(b)` (where, `r_(f)` and `r_(b)` are rates of forward and backward reaction respectively)

Answer

To determine the nature of a chemical reaction based on the Gibbs free energy change (ΔG), we can follow these steps:

### Step 1: Understand the Concept of Gibbs Free Energy (ΔG)
Gibbs free energy (ΔG) is a thermodynamic potential that helps predict whether a reaction will occur spontaneously. It is defined as:
\[ \Delta G = \Delta H - T \Delta S \]
where:
- ΔH = change in enthalpy (heat content)
- T = temperature in Kelvin
- ΔS = change in entropy (disorder)

### Step 2: Analyze the Significance of ΔG
- If ΔG < 0 (negative), the reaction is spontaneous. This means the reaction can proceed without any external input of energy.
- If ΔG = 0, the system is at equilibrium, and there is no net change in the concentration of reactants and products.
- If ΔG > 0 (positive), the reaction is non-spontaneous, meaning it requires energy input to occur.

### Step 3: Relate ΔG to Spontaneity
For a reaction to be spontaneous, it must move towards a lower energy state, which is thermodynamically stable. This is often accompanied by the release of heat (exothermic reaction) or an increase in entropy.

### Step 4: Conclusion
Since the question states that the free energy change (ΔG) is negative, we conclude that the reaction is spontaneous.

### Final Answer
The reaction is **spontaneous** when ΔG is negative.

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