Answer: The activation energy for backward reaction is +25 kJ
Explanation:
For the given chemical equation:
[tex]A+B\rightleftharpoons C[/tex]
We are given:
Enthalpy of the reaction = -20 kJ
As, the enthalpy of the reaction is negative, the reaction is said to be exothermic in nature.
To calculate the activation energy for the reverse reaction, we use the equation:
[tex]E_a_{\text{(backward)}}=E_a_{\text{(forward)}}+|\Delta H\[/tex]
where,
[tex]E_a_{\text{(forward)}}[/tex] = Activation energy of the forward reaction = 5 kJ
[tex]E_a_{\text{(backward)}}[/tex] = Activation energy of the backward reaction = ?
[tex]\Delta H[/tex] = Enthalpy of the reaction = -20 kJ
Putting values in above equation, we get:
[tex]E_a_{\text{(backward)}}=5+|-20|\\\\E_a_{\text{(backward)}}=25kJ[/tex]
Hence, the activation energy for backward reaction is +25 kJ
