Consider the gas-phase reaction: H₂(g) + I₂(g) → 2 HI(g) The reaction was experimentally determined to be first order in H₂ and first order in I₂. Consider the proposed mechanisms. Proposed mechanism I: H₂(g) + I₂(g) → 2 HI(g) Single step Proposed mechanism II: I₂(g) Δk1k-12 I(g) Fast H₂( g) + 2 I( g) → k22 HI( g) Slow a. Show that both of the proposed mechanisms are valid.

Video transcript

Hi everyone here we have a question asking us to consider the reaction below A plus C. Two forms A C. To the reaction is forced to order and a. And first order in C. +22 mechanisms are proposed for the reaction mechanism one A plus C. Two forms a C. Two mechanism to B plus C. Two forms B C plus C. Slow. A plus B. C forms A P plus C. Fast and A B plus two C. Forms A C. Two plus B. Fast. Are both mechanisms valid and if yes. Why? So let's see what we have here. We have B. C. And we have A B. And we have to see we have one see here, one see here and then to see here. So that gives us A plus C. Two Forms AC. two. So the overall reaction for mechanism to adds up to look like the overall reaction given and mechanism one. However, the first step in mechanism to is slow. This means the rate law will be based on it. This will not match the orders which are given, which is first order in A. And second order. And see A would not be first order in the rate law since it is not the right determining step. So our answer is no because the right law will not be the same. And that is our final answer. Thank you for watching. Bye.