Arrange the following reactions in increasing order of the value of the ratio of rate constants ($k_{310}/k_{300}$) (A) $A+B → C: E_a = 70\, kJ$ Choose the correct answer from the options given below: |
(A), (B), (C), (D) (B), (A), (C), (D) (D), (C), (A), (B) (C), (B), (D), (A) |
(B), (A), (C), (D) |
The correct answer is Option (2) → (B), (A), (C), (D) Core Formula (Arrhenius Ratio): $\ln \left( \frac{k_{310}}{k_{300}} \right) = \frac{E_a}{R} \left( \frac{1}{300} - \frac{1}{310} \right)$ $\frac{1}{300} - \frac{1}{310} = \frac{10}{93000} = 1.075 \times 10^{-4}$ $R = 8.314 \, \text{J mol}^{-1} \text{K}^{-1}$ (A) $E_a = 70 \, \text{kJ} = 70000 \, \text{J}$: $\ln \left( \frac{k_{310}}{k_{300}} \right) = \frac{70000}{8.314} \times 1.075 \times 10^{-4}$ $= 8421 \times 1.075 \times 10^{-4} = 0.905$ $\frac{k_{310}}{k_{300}} = e^{0.905} \approx 2.47$ (B) $E_a = 45 \text{ kJ} = 45000 \text{ J}$ $\ln\left(\frac{k_{310}}{k_{300}}\right) = \frac{45000}{8.314} \times 1.075 \times 10^{-4}$ $= 5413 \times 1.075 \times 10^{-4} = 0.582$ $\frac{k_{310}}{k_{300}} = e^{0.582} \approx 1.79$ (C) $E_a = 95 \text{ kJ} = 95000 \text{ J}$ $\ln\left(\frac{k_{310}}{k_{300}}\right) = \frac{95000}{8.314} \times 1.075 \times 10^{-4}$ $= 11428 \times 1.075 \times 10^{-4} = 1.229$ $\frac{k_{310}}{k_{300}} = e^{1.229} \approx 3.42$ (D) $E_a = 100 \text{ kJ} = 100000 \text{ J}$ $\ln\left(\frac{k_{310}}{k_{300}}\right) = \frac{100000}{8.314} \times 1.075 \times 10^{-4}$ $= 12027 \times 1.075 \times 10^{-4} = 1.293$ $\frac{k_{310}}{k_{300}} = e^{1.293} \approx 3.64$ Comparison:
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