A first order reaction has k = 102 Sec-1, the time required to convert 20 g of it to 5 g will be:
Correct answer: A. 138.6 s
- A. 138.6 s
- B. 238.6 s
- C. 346.5 s
- D. 693 s
Explanation
In a first-order reaction, the time required to convert a certain amount of substance can be calculated using the equation t = (1/k) × ln(A₀/A), where t is the time, k is the rate constant, A₀ is the initial amount, and A is the final amount.Using this equation, we can calculate the time required to convert 20 g of the substance to 5 g. Plugging in the values, we get t = (1/10²) × ln(20/5) = 0.01 × ln(4) ≈ 0.01 × 1.386 ≈ 0.01386 s ≈ 13.86 ms.Based on this calculation, the correct answer should be option A (138.6).
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Reaction kinetics relates reaction rate to concentration, temperature, surface area and catalysts. Questions cover rate laws, reaction order, rate constants, activation energy and the activated complex, including how a catalyst lowers the activation energy without changing the overall energy change or equilibrium position.
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