The expression of rate constant given in the question ( $\left.k = PZ e ^{(- Ea / RT )}\right)$ is according to Arrhenius theory.
To speed up the reaction, we will have to decrease the value of $E_{a}$ i.e. activation energy and will have to increase the value of temperature $(T)$ and the number of collisions $(Z)$.
The rate constant \( k \) is given by the equation: \[ k = P Z e^{-E_a/RT} \] where:
\( P \) is the pre-exponential factor,
\( Z \) is the collision frequency,
\( E_a \) is the activation energy,
\( R \) is the gas constant,
\( T \) is the temperature.
To speed up the reaction, we need to increase \( k \), which is the rate constant.
\( k \) depends on the exponential term \( e^{-E_a/RT} \), which is directly related to the activation energy \( E_a \) and temperature \( T \).
Decreasing \( E_a \) (activation energy) will increase the rate constant \( k \), which will speed up the reaction.
While increasing \( T \) increases \( k \), the question asks for the factor to decrease, so decreasing \( E_a \) is the correct answer.
Thus, the correct answer is: \[ {\text{Decreasing \( E_a \) (activation energy) will speed up the reaction.}} \]
The following data were obtained during the first order thermal decomposition of \( \text{N}_2\text{O}_5(g) \) at constant volume:
Chemical kinetics is the description of the rate of a chemical reaction. This is the rate at which the reactants are transformed into products. This may take place by abiotic or by biological systems, such as microbial metabolism.
The speed of a reaction or the rate of a reaction can be defined as the change in concentration of a reactant or product in unit time. To be more specific, it can be expressed in terms of: (i) the rate of decrease in the concentration of any one of the reactants, or (ii) the rate of increase in concentration of any one of the products. Consider a hypothetical reaction, assuming that the volume of the system remains constant. R → P
Read More: Chemical Kinetics MCQ