A second-order reaction has a rate constant of 1.25 M^-¹.s^-¹ .If the initial reactant concentration is 1.0 M,Calculate the time required for 90% reaction. A) 1.3 s B) 7.2 s C) 0.13 s D) 17 s E) 0.89 s

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Quizplus · Accepted Answer

For a second-order reaction, the rate equation is $ \frac{1}{[A]_t} - \frac{1}{[A]_0} = kt $, where $ [A]_t $ is the concentration at time $ t $, $ [A]_0 $ is the initial concentration, and $ k $ is the rate constant. If 90% of the reactant reacts, the final concentration $ [A]_t $ is 0.1 M (since 90% of 1.0 M has reacted). Substituting the given values: $ \frac{1}{0.1} - \frac{1}{1.0} = 1.25t $. Solving for $ t $ gives $ t = 7.2 $ seconds.

A Second-Order Reaction Has a Rate Constant of 1