Chemical KineticshardMCQ SINGLE⭐ Must-Do

Unlike first-order reactions which theoretically never finish, a zero-order reaction reaches 100% coChemical Kinetics Chemistry Question

Question

Unlike first-order reactions which theoretically never finish, a zero-order reaction reaches 100% completion in a mathematically finite time. What is the exact formula for the time of 100% completion ($t_{100\%}$) in terms of initial concentration $[A]_0$ and rate constant $k$?

Answer: A

💡 Solution & Explanation

The integrated rate law for a zero-order reaction is $[A]_t = [A]_0 - kt$. At 100% completion, the remaining concentration $[A]_t = 0$. Substituting this gives $0 = [A]_0 - kt_{100\%}$, which elegantly rearranges to $t_{100\%} = [A]_0 / k$.

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