What is the thermodynamic criteria for the feasibility of a reaction ?

Answer

To determine the thermodynamic criteria for the feasibility of a reaction, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Spontaneity**:
- A reaction is said to be spontaneous if it occurs without needing to be driven by an external force. This is a key aspect of feasibility.

2. **Entropy Change**:
- For a reaction to be feasible, the total change in entropy (ΔS) of the system and its surroundings must be considered. The criterion states that:
\[ ΔS_{\text{total}} = ΔS_{\text{system}} + ΔS_{\text{surroundings}} > 0 \]
- This means that the sum of the entropy changes must be positive.

3. **Gibbs Free Energy**:
- Another important parameter is the Gibbs free energy change (ΔG). The relationship between Gibbs free energy and spontaneity is given by:
\[ ΔG = ΔH - TΔS \]
- For a reaction to be spontaneous, ΔG must be negative:
\[ ΔG < 0 \]

4. **Conditions for Spontaneity**:
- Therefore, the conditions for a reaction to be feasible (spontaneous) can be summarized as:
- **Total Entropy Change**: \( ΔS_{\text{total}} > 0 \)
- **Gibbs Free Energy Change**: \( ΔG < 0 \)

5. **Conclusion**:
- If both conditions are satisfied, the reaction is considered thermodynamically feasible or spontaneous.

### Summary of Thermodynamic Criteria:
- **Total Entropy Change**: \( ΔS_{\text{total}} > 0 \)
- **Gibbs Free Energy Change**: \( ΔG < 0 \)