Question

Consider the given figure and choose the correct option:

• A. Activation energy of both forward and backward reaction is \( E_1 + E_2 \) and reactant is more stable than product.
• B. Activation energy of backward reaction is \( E_1 \) and product is more stable than reactant.
• C. Activation energy of forward reaction is \( E_1 + E_2 \) and product is less stable than reactant.
• D. Activation energy of forward reaction is \( E_1 + E_2 \) and product is more stable than reactant.

Hint:

In energy diagrams, the activation energy for the forward reaction is measured from the reactant to the activated complex, and the activation energy for the reverse reaction is measured from the product to the activated complex.

Answer 1

The Correct Option is D

The given figure represents a typical energy profile diagram for a chemical reaction. It shows the energy of reactants, products, and the activated complex (transition state). Two energy differences are marked:

• E₁: Energy difference between the product and the activated complex.
• E₂: Energy difference between the reactant and the product.

1. Forward Activation Energy

The forward activation energy is the energy needed to convert reactants into the activated complex. This is the total vertical energy gap from the reactant level to the peak of the curve.

Reactant → Product = E₂
Product → Activated complex = E₁
So, forward activation energy = E₁ + E₂

2. Backward Activation Energy

Backward activation energy is the energy required for the reverse reaction (product → activated complex). This is simply the energy gap between product and the activated complex:

Backward activation energy = E₁

3. Stability of Reactant vs Product

Stability is inversely related to energy: a species with lower energy is more stable.

In the diagram, the product is at a higher energy level than the reactant. Therefore, the product is less stable and the reactant is more stable.

Conclusion

• Forward activation energy = E₁ + E₂
• Product is less stable than reactant

These statements match exactly with Option 3.

Correct Answer: Option 3

Answer 2

In the given reaction coordinate diagram: - \( E_1 \) represents the activation energy of the forward reaction. - \( E_2 \) represents the activation energy of the reverse reaction. - The total energy for the forward reaction is \( E_1 + E_2 \), and the product is more stable than the reactant as indicated by the lower position of the product compared to the reactant on the energy scale. Thus, the correct option is option (4).