Question

An endothermic reaction $A\to B$ has an activation energy $15kcal/mole$ and the heat of reaction is $5kcal/mole$. The activation energy of reaction $B\to A$ is:

• A. $20kcal/mole$
• B. $15kcal/mole$
• C. $10kcal/mole$
• D. zero

Answer 1

The correct option is A $20kcal/mole$

Activation energy=$15kcal/mole$

Heat of reaction=$5kcal/mole$

Total $E_a=20kcal/mol$

For $A\to B$

For any reaction the activation energy in the forward direction is numerically equal to activation energy of reaction in backward direction.

Therefore $E_a$ for $B\to A$ is 20 kcal/mole and option [A] is correct answer.