Question

For the reaction of A + B ⇌ C the activation energy of the forward reaction is 5kJ and the total energy change for the reaction is -20kJ. What is the activation energy of the reverse reaction? Group of answer choices 25 20 5 15

Answer 1

Answer: The activation energy for backward reaction is +25 kJ

Step-by-step explanation:

For the given chemical equation:

`A+B\rightleftharpoons C`

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:

`E_a_{\text{(backward)}}=E_a_{\text{(forward)}}+|\Delta H\`

where,

`E_a_{\text{(forward)}}` = Activation energy of the forward reaction = 5 kJ

`E_a_{\text{(backward)}}` = Activation energy of the backward reaction = ?

`\Delta H` = Enthalpy of the reaction = -20 kJ

Putting values in above equation, we get:

`E_a_{\text{(backward)}}=5+|-20|\\\\E_a_{\text{(backward)}}=25kJ`

Hence, the activation energy for backward reaction is +25 kJ