Question

For a reaction $X\to Y)$, heat of reaction is $+83.68kJ$, energy of reactant $X$ is $167.36kJ$ and energy of activation is $209.20kJ$. Calculate (i) threshold energy (ii) energy of product $Y$ and (iii) energy activation of the reverse reaction $(Y\to X)$.

Answer 1

(i) Given, the energy of activation for forward reaction $E_a\left(f\right)=209.20kJ$
The heat of reaction $\Delta E=+83.68kJ$
Energy of reactant, $X=167.36kJ$
Threshold energy $=$ Energy of reactant $X+$ Activation energy for
forward reaction.
Threshold energy $=167.36+209.20=376.56kJ$
(ii) Energy of reaction, $\Delta E=$ Energy of product $-$ Energy of
reactant
Energy of product $=$ Energy of reaction, $\Delta E+$ Energy of
reactant
Energy of product $=83.68+167.36=251.04kJ$
(iii) Activation energy for backward reaction
$=$ Threshold energy $-$ Energy of product
Activation energy for backward reaction $=376.56-251.04=125.52kJ$