For the consecutive first-order reactions: A -(K1)-> B -(K2)-> C, in what condition, [C] = [A_0] × ( — Chemical Kinetics Chemistry Question

💡 Solution & Explanation

In a consecutive reaction A -> B -> C, if the second step is extremely fast compared to the first step (K2 >> K1 or K1 << K2), B acts as a highly reactive intermediate with negligible concentration ([B] ≈ 0). Thus, any A that reacts is instantly converted to C, so [C] = [A_0] - [A] = [A_0](1 - e^(-K1*t)). While K1 << K2 is the correct physical condition, the book's printed answer key lists (b) as the correct option.