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 rate of a chemical reaction is related to the activation energy by the Arrhenius equation.
Reducing the activation energy ( E a ) increases the value of − RT E a .
Since e x is an increasing function, increasing − RT E a increases the rate constant k .
Therefore, reducing the activation energy increases the rate of the reaction. The answer is: The rate would increase.
Explanation
Understanding the Problem The question asks about the effect of reducing the activation energy on the rate of a chemical reaction. We need to determine whether the rate would increase, decrease, remain the same, or become zero.
Recalling the Arrhenius Equation The rate of a chemical reaction is related to the activation energy by the Arrhenius equation: k = A e − RT E a where:
k is the rate constant (proportional to the reaction rate),
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 Reducing Activation Energy We are interested in how the rate constant k changes when the activation energy E a is reduced. Let's analyze the exponent in the Arrhenius equation, − RT E a . If E a decreases, then − RT E a increases (i.e., becomes less negative) because R and T are positive constants.
Determining the Change in Reaction Rate Since the exponential function e x is an increasing function, if the exponent − RT E a increases, then e − RT E a also increases. Therefore, if E a decreases, then k increases, which means the rate of the reaction increases.
Conclusion Therefore, if the activation energy required for a chemical reaction is reduced, the rate of the reaction would increase.
Examples
In the food industry, enzymes are used to speed up reactions, such as breaking down starches into sugars. By reducing the activation energy of these reactions, the enzymes allow processes like fermentation to occur much faster, improving production efficiency. Similarly, in the development of new medications, catalysts are used to lower the activation energy of key reactions, enabling the synthesis of complex drug molecules more quickly and at lower temperatures, which can reduce costs and environmental impact.
If the activation energy for a chemical reaction is reduced, the reaction rate will increase. This is because lowering activation energy allows reactants to overcome the energy barrier more easily, leading to a higher rate constant. Therefore, the correct answer is A: The rate would increase.
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