Which of the following can help to predict the rate of reaction if the standard Gibb's free energy of reaction `(Delta_rG^@)` is known ?

Options

A. Equilibrium constant
B. `Delta_rH^@`
C. `Delta_rU^@`
D. Heat liberated during the course of reaction in calorimeter

Answer

To solve the question of which factor can help predict the rate of reaction if the standard Gibbs free energy of reaction (Δ_rG°) is known, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Gibbs Free Energy**:
The standard Gibbs free energy change (Δ_rG°) is a thermodynamic quantity that indicates the spontaneity of a reaction. If Δ_rG° is negative, the reaction is spontaneous; if positive, it is non-spontaneous.

2. **Relation to Equilibrium Constant**:
The relationship between Δ_rG° and the equilibrium constant (K) is given by the equation:
\[ Δ_rG° = -2.303RT \log K \]
where R is the gas constant and T is the temperature in Kelvin. This equation shows that knowing Δ_rG° allows us to calculate the equilibrium constant K.

3. **Predicting Rate of Reaction**:
The rate of a reaction is related to how quickly reactants are converted into products. While Δ_rG° and K provide information about the position of equilibrium and spontaneity, they do not directly provide the rate of reaction. However, the equilibrium constant (K) can give insights into the concentrations of reactants and products at equilibrium, which indirectly relates to the rate.

4. **Evaluating Options**:
- **Option 1: Equilibrium Constant (K)** - This is correct, as it can be derived from Δ_rG° and gives insights into the reaction's behavior.
- **Option 2: ΔH° (Enthalpy of Reaction)** - This does not directly relate to the rate of reaction.
- **Option 3: Internal Energy** - This is also not directly related to the rate of reaction.
- **Option 4: Heat Liberated** - While it provides information about the reaction, it does not predict the rate of reaction.

5. **Conclusion**:
The only option that can help predict the rate of reaction when Δ_rG° is known is the equilibrium constant (Option 1).

### Final Answer:
**The correct answer is Option 1: Equilibrium Constant.**