Question

Analyze the energy diagram below for a reaction.

Which area on the graph is not directly related to the overall reaction being exothermic or endothermic?
(A) 1
(B) 2
(C) 3
(D) 4

Answer 1

Hint: For this problem, firstly we have to study the activation energy and about exothermic and endothermic reactions. So that we can determine the correct area which does not directly depend on the overall reaction.

Complete step by step solution:
-In the given question, we have to explain which area on the graph does not show a direct relationship with the overall reaction.
-The given graph represents the type reaction whether it is in forwarding direction or a backward direction or whether it is an exothermic or endothermic reaction.
-Now, the activation energy is defined as the energy which is required for an atom to initiate the process of a chemical reaction.
-This activation energy helps the reaction to initiate in the forward direction that is from reactant to the product.
-In between the reaction completion, there is a state known as transition state which has higher energy than the reactant and product.
-In the given graph, part A represents the energy of reactant i.e. ${{\text{E}}_{\text{A}}}$which will proceed into the chemical reaction to form the product B i.e. ${{\text{E}}_{\text{B}}}$.
-Whereas the position (3) shows the difference between the energy of reactant and product which is given by: ${{\text{E}}_{\text{B}}}\text{ - }{{\text{E}}_{\text{A}}}$.
-So, we can say these three positions are directly related to the overall reaction because if the energy of A will be more than the energy of B then the reaction will be exothermic and vice versa.
-But the position (2) represents the activation energy which does not have a direct relationship with overall reaction because it only helps in initiating the process and doesn't tell whether it is exothermic or endothermic.

Therefore, option (B) is the correct answer.

Note: The transition state formed is unstable because the molecules start to break down and convert into the product. Moreover, the exothermic reaction yields heat and increases the temperature.