Question

Which factor when increased will cause an uncatalyzed reaction to proceed more quickly?
A.Exothermic
B.Particle size
C.Endothermic
D.Catalyst

Answer 1

Hint:To solve this question, you must recall the factors that affect the rate of a reaction. The difference between the energies of the reactants and the products gives us the enthalpy of the reaction. Activation energy is the energy that we need to provide to compounds in order for a chemical reaction to take place.

Complete step by step solution:
If the energy of the reactants is more than the energy of the products, heat is evolved in the reaction. Such a reaction is known as an exothermic reaction. While if the energy of the reactants is less than the energy of the products, heat is absorbed in the reaction and the reaction is known as endothermic.
An exothermic reaction is generally spontaneous as the product formed is more stable than the reactants. Thus, they can be carried out without catalysts as well and increasing the exothermic factor of the reaction would increase the rate of the reaction.

Thus, the correct answer is A.

Note:
Activation energy can be considered as the magnitude of the energy barrier separating the initial and final thermodynamic states, namely the reactants and products. For a chemical reaction to occur at a good rate, the temperature of the system should be high enough so that there are an appreciable number of molecules with energy greater than or equal to the activation energy. The activation energy $\left( {{{\text{E}}_{\text{a}}}} \right)$ is commonly measured in joules per mol.
${\text{k = A}}{{\text{e}}^{\dfrac{{ - \left( {{{\text{E}}_{\text{a}}}} \right)}}{{{\text{RT}}}}}}$ is known as the Arrhenius equation, which gives a relation between the activation energy of the reaction and the rate at which the reaction proceeds. We can see from this equation that more the activation energy, slower will be the reaction.