Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain the difference between an elementary step and an overall reaction. (Guide: “One collision, one step”)
- I can explain why the rate of an elementary step is proportional to the product of the reactant concentrations, each raised to its coefficient. (Guide: Figure 1; Practice Q7)
- I can define molecularity and classify a step as unimolecular, bimolecular or termolecular. (Guide: “Molecularity”; Practice Q2)
- I can explain why termolecular steps are rare and why steps with four or more particles are not expected. (Guide: “Why three-particle collisions are rare”; Practice Q7)
Skills
- I can write the rate law of an elementary step from its equation, leaving out the products. (Guide: Worked example 1; Practice Q1)
- I can give the units of k for a unimolecular, bimolecular or termolecular step. (Guide: Worked example 1; Practice Q5)
- I can calculate the rate of an elementary step from k and the concentrations. (Guide: Worked example 2; Practice Q4)
- I can predict the factor by which the rate changes when one or more concentrations change. (Practice Q3, Q4)
Reasoning
- I can compare an experimental rate law with the one a single elementary step predicts, and say what the comparison shows. (Guide: Worked example 3; Practice Q5, Q6)
- I can explain why a matching rate law does not prove a reaction is one elementary step. (Practice Q5)
- I can spot an overall equation that cannot be a single step because too many particles would have to collide. (Guide: Worked example 3)
All ticked? Move on to Topic 5.5, Collision Model, or return to the course roadmap.