Based on their activation energies and energy changes and assuming that all collision factors are the same, which of the following reactions would be fastest in the reverse direction?

Reaction with Ea value of 35kj is the fastest(option b) and reaction with Ea value of 55kj/mol is the slowest (option c).

Explanation:

Let's start with the definition of rate of reaction and activation energy.

WHAT DOES RATE OF REACTION MEAN ?.

Rate of reaction measures the time at which reactants are converted into products. It is the concentration of reactants that is consumed in a chemical reaction per unit time.

WHAT DOES ACTIVATION ENERGY MEAN ?.

Activation energy can be defined as the energy required for a chemical reaction to take place.

HOW DOES ACTIVATION ENERGY RELATES TO RATE OF REACTION?.

The higher the activation energy, the slower the rate of reaction and the lower the activation energy, the faster the rate of reaction.

Hence, from the question the value of Ea for option (c) which is 55kj/mol is higher than that of option (b) and (a) with Ea values of 35kj/mol and 45kj/mol Respectively. Therefore, Option (c) is the SLOWEST.

Option (b) which has the lowest Ea of 35kj/mol is the FASTEST.