Free response · Unit 5 Beta

Nitrogen monoxide and ozone high in the air

Short free response · 4 points

The question

Name: ______________________   Date: ____________   Nitrogen monoxide and ozone high in the air (4 points)

Model

A two-step mechanism

High in the atmosphere, oxygen atoms and ozone react: O₃(g) + O(g) → 2 O₂(g). The reaction is slow on its own, but much faster when a small amount of nitrogen monoxide, NO, is present. A proposed mechanism with NO:

  1. NO(g) + O₃(g) → NO₂(g) + O₂(g)  (slow)
  2. NO₂(g) + O(g) → NO(g) + O₂(g)  (fast)

  1. (a) Show that the two steps add up to the overall reaction. [1 point]

  2. (b) Identify the catalyst and the intermediate in the mechanism. Justify each choice. [2 points]

  3. (c) Write the rate law for the overall reaction that is consistent with the mechanism, and explain your reasoning. [1 point]