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The rate constants k(1) and k(2) of two ...

The rate constants `k_(1)` and `k_(2)` of two reactions are in the ratio `2:1`. The corresponding energies of acativation of the two reaction will be related by

A

`E_(1) gt E_(2)`

B

`E_(1) gt E_(2)`

C

`E_(1)=E_(2)`

D

`E_(1)=2E_(2)`

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The correct Answer is:
To solve the problem, we will use the Arrhenius equation, which relates the rate constant of a reaction to its activation energy. The Arrhenius equation is given by: \[ k = A e^{-\frac{E_a}{RT}} \] where: - \( k \) is the rate constant, - \( A \) is the pre-exponential factor, - \( E_a \) is the activation energy, - \( R \) is the universal gas constant, - \( T \) is the temperature in Kelvin. ### Step-by-Step Solution: 1. **Write the Arrhenius equation for both reactions:** For the first reaction: \[ k_1 = A_1 e^{-\frac{E_1}{RT}} \] For the second reaction: \[ k_2 = A_2 e^{-\frac{E_2}{RT}} \] 2. **Use the given ratio of rate constants:** We are given that: \[ \frac{k_1}{k_2} = \frac{2}{1} \] This implies: \[ k_1 = 2k_2 \] 3. **Substitute the Arrhenius equations into the ratio:** \[ \frac{A_1 e^{-\frac{E_1}{RT}}}{A_2 e^{-\frac{E_2}{RT}}} = 2 \] 4. **Rearranging the equation:** \[ \frac{A_1}{A_2} e^{-\frac{E_1 - E_2}{RT}} = 2 \] 5. **Assuming equal pre-exponential factors (A1 = A2):** If we assume that the pre-exponential factors are approximately equal (which is a common assumption), we can simplify the equation to: \[ e^{-\frac{E_1 - E_2}{RT}} = 2 \] 6. **Taking the natural logarithm of both sides:** \[ -\frac{E_1 - E_2}{RT} = \ln(2) \] Rearranging gives: \[ E_1 - E_2 = -RT \ln(2) \] 7. **Interpreting the result:** Since \( \ln(2) \) is a positive value, this means: \[ E_1 < E_2 \] Therefore, we conclude that the activation energy for the second reaction (E2) is greater than that for the first reaction (E1). ### Conclusion: The correct relationship between the activation energies is: \[ E_2 > E_1 \]

To solve the problem, we will use the Arrhenius equation, which relates the rate constant of a reaction to its activation energy. The Arrhenius equation is given by: \[ k = A e^{-\frac{E_a}{RT}} \] where: - \( k \) is the rate constant, - \( A \) is the pre-exponential factor, - \( E_a \) is the activation energy, ...
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