If the activation energy required for a chemical reaction were reduced, what would happen to the rate of the reaction?
A. The rate would increase.
B. The rate would decrease.
C. The rate would remain the same.
D. The rate would be zero.
Answer (2)
The activation energy ( E a ) is reduced.
The Arrhenius equation k = A e − E a / RT relates the rate constant k to E a .
Reducing E a makes the exponent − E a / RT less negative, increasing e − E a / RT .
An increase in e − E a / RT leads to an increase in the rate constant k , thus the reaction rate increases. The rate would increase .
Explanation
Understanding the Problem The question asks about the effect of reducing the activation energy ( E a ) on the rate of a chemical reaction. We need to determine if the rate increases, decreases, remains the same, or becomes zero.
Recalling the Arrhenius Equation The Arrhenius equation describes the relationship between the rate constant k (which is directly proportional to the reaction rate) and the activation energy E a : k = A e − E a / RT where:
k is the rate constant
A is the pre-exponential factor
E a is the activation energy
R is the gas constant
T is the temperature
Analyzing the Effect of Reduced Activation Energy We are given that the activation energy E a is reduced. Let's analyze how this affects the term e − E a / RT . Since E a is in the exponent and has a negative sign, reducing E a (making it smaller) will make the exponent less negative. For example, if E a is initially 100 and is reduced to 50, then − E a changes from -100 to -50.
Determining the Impact on the Exponential Term A less negative exponent means that the value of e − E a / RT will increase. For example, consider e − 100/ RT and e − 50/ RT . Since -50 is greater than -100, e − 50/ RT will be greater than e − 100/ RT .
Concluding the Effect on Reaction Rate Since k is directly proportional to e − E a / RT , an increase in e − E a / RT will lead to an increase in k . Therefore, the rate of the reaction will increase.
Final Answer Therefore, if the activation energy required for a chemical reaction is reduced, the rate of the reaction would increase. The correct answer is: O The rate would increase.
Examples
In the food industry, enzymes are used to speed up reactions like cheese production or bread making. By reducing the activation energy of these reactions, the enzymes allow the processes to occur faster and at lower temperatures, which can save energy and improve efficiency. Similarly, in the development of new medications, catalysts are used to lower the activation energy of reactions that produce the desired drug, making the synthesis more efficient and cost-effective. This principle is crucial in optimizing various industrial and chemical processes.
Reducing the activation energy of a reaction makes it easier for molecules to collide with enough energy to react. This leads to an increase in the rate constant according to the Arrhenius equation, ultimately raising the reaction rate. Thus, if the activation energy is decreased, the rate of the reaction would increase.
;
