Question

For an endothermic reaction, energy of activation is $E_a$ and enthalpy of reaction is $\Delta H$ (both of these in kJ/mol). Minimum value of $E_a$ will be:

• A. Less than $\Delta H$
• B. Equal to $\Delta H$
• C. More than $\Delta H$
• D. Equal to zero

Answer 1

The correct option is C

More than $\Delta H$

In endothermic reactions, energy of reactants is less than that of the products.Potential energy diagram for endothermic reactions is

Where
$E_a$ = activation energy of forward reaction
$E_a^{\prime }$= activation energy of backward reaction
$\Delta H$ =enthalpy of the reaction.
From the above diagram,
$E_a=E_a^{\prime }+\Delta H$
Thus, $E_a>\Delta H$