Question

For an endothermic reaction, energy of activation is E_a and enthalpy of reaction is ΔH (both of these in kJ/mol). Minimum value of E_a will be ______.

विकल्प

• less than ΔH

• equal to ΔH

• more than ΔH

• equal to zero

Answer 1

For an endothermic reaction, energy of activation is E_a and enthalpy of reaction is ΔH (both of these in kJ/mol). Minimum value of E_a will be more than ΔH.

Explanation:

For an endothermic reaction, the energy profile looks like this:

Products are higher in energy than reactants. So, the activation energy E_a must account for the energy needed to reach the transition state, which lies above both reactants and products. And this must be greater than the net enthalpy change ΔH, since:

\[\ce{E_a = \Delta H + E{^{(reverse)}_{a}}}\]

⇒ E_a ​> ΔH