Question

If the activation energy for the forward reaction is \( 150 \, \text{kJ/mol} \) and that of the reverse reaction is \( 260 \, \text{kJ/mol} \), what is the enthalpy change for the reaction?

• A. \( 410 \, \text{kJ/mol} \)
• B. \( -110 \, \text{kJ/mol} \)
• C. \( 110 \, \text{kJ/mol} \)
• D. \( -410 \, \text{kJ/mol} \)

Hint:

In exothermic reactions, the activation energy of the reverse reaction is higher than that of the forward reaction, resulting in a negative enthalpy change (\( \Delta H \)).

Answer 1

The Correct Option is B

The enthalpy change (ΔH) for a reaction is the difference between the activation energy of the forward reaction (Ea_forward) and the activation energy of the reverse reaction (Ea_reverse):

ΔH = Ea_forward - Ea_reverse

Given:

• Ea_forward = 150 kJ/mol
• Ea_reverse = 260 kJ/mol

Substituting the values:

ΔH = 150 kJ/mol - 260 kJ/mol

ΔH = -110 kJ/mol

Therefore, the enthalpy change for the reaction is -110 kJ/mol.

Final Answer: -110 kJ/mol