Which of the following statements concerning a possible mechanism for a reaction is false?

• A. Each elementary step in the mechanism should involve a small number of molecules colliding.
• B. The sum of the elementary steps in the mechanism must give the overall balanced equation for the reaction.
• C. All intermediates in the mechanism must appear in the overall balanced equation.
• D. A valid mechanism must have a rate law that matches the experimentally determined rate law.

Answer: (C)

Verified step by step guidance

1. Understand that a reaction mechanism is a series of elementary steps that describe how reactants convert to products at the molecular level.
2. Recall that each elementary step typically involves a small number of molecules colliding, often one or two, because complex collisions are statistically unlikely.
3. Recognize that when you add all the elementary steps together, the intermediates cancel out, and the sum must equal the overall balanced chemical equation for the reaction.
4. Know that intermediates are species formed and consumed during the mechanism and therefore do not appear in the overall balanced equation, which only shows reactants and products.
5. Remember that a valid mechanism must produce a rate law consistent with the experimentally observed rate law, ensuring the mechanism accurately reflects the reaction kinetics.