KCET2026ChemistryChemical Kinetics
The activation energy for the reaction X Y is 150 kJ mol ⁻¹ . The change in enthalpy for the above reaction is -135 kJ mol ⁻¹ . Then the activation energy for Y X is
Options
- A280 kJ mol ⁻¹
- B285 kJ mol ⁻¹
- C270 kJ mol ⁻¹
- D15 kJ mol ⁻¹
Correct answer
B. 285 kJ mol ⁻¹
Step-by-step solution
The change in enthalpy for a reaction is related to the activation energies of the forward and backward reactions by the equation: H = E_ a(f) - E_ a(b) Given: E_ a(f) = 150 kJ mol ⁻¹ H = -135 kJ mol ⁻¹ Substituting the values into the equation: -135 = 150 - E_ a(b) E_ a(b) = 150 + 135 E_ a(b) = 285 kJ mol ⁻¹ The activation energy for the reverse reaction Y X is 285 kJ mol ⁻¹ . Answer: 285 kJ mol ⁻¹