For an endothermic reaction, energy of activation is $E_a$ and enthalpy of reaction is $\Delta H$ (both of…

For an endothermic reaction, energy of activation is $E_a$ and enthalpy of reaction is $\Delta H$ (both of these in $\mathrm{kJ} / \mathrm{mol}$ ). Minimum value of $E_a$ will be
  1. less than $\Delta \mathrm{H}$
  2. equal to $\Delta \mathrm{H}$
  3. more than $\Delta \mathrm{H}$
  4. equal to zero

Solution

In endothermic reactions, energy of reactants is less than that of the products. Potential energy diagram for endothermic reactions is, where, $\mathrm{E}_{\mathrm{a}}=$ activation energy of forward reaction $\mathrm{E}_{\mathrm{a}}^{\prime}=$ activation energy of backward reaction $\Delta \mathrm{H}=$ enthalpy of the reaction From the above diagram, $\mathrm{E}_{\mathrm{a}}=\mathrm{E}_{\mathrm{a}}^{\prime}+\Delta \mathrm{H}$ Thus, $\mathrm{E}_{\mathrm{a}} > \Delta \mathrm{H}$

Asked in: NEET 2010 (Screening)

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