Chemical Kinetics! While this topic might conjure up some harsh memories from college chem, your kids will probably like this topic. It’s logical, and they can easily observe how the changes they make to the reactants affect the rate at which the reaction occurs. And you don’t have to dive deep to help your students understand the basics. So never fear, fellow educator! Your students can learn rates of reactions and still enjoy your class.
I prefer to teach this unit after solutions, usually along with equilibrium, because then we already know how to calculate molarity. My colleague believes it should be taught with Thermochemistry because temperature is a factor in increasing reaction rates. If your thermochemistry unit falls after solutions and equilibrium, then there’s no problem. For us, though… we do:
Gas Laws → Thermochemistry → Solutions → Equilibrum → Acids and Bases
This year we’re going to try teaching it during the thermochemistry unit. We don’t go fully into kinetics, just a few days of learning about the factors that can increase a reaction rate. Because this unit can be taught well in multiple places, I’m labeling it a “mini-unit”. Slot it in when you have some weird calendar days you need to plan around.
Rate of Reaction Mini Unit – Lesson Plans
Total Duration: 4-5 days
Note: a day refers to 45-50 minute periods.
| Topic & Timeline | Tasks | Description |
| What increases the rate of a reaction? 1-2 days | Alka-Seltzer Lab* Whiteboard Meeting + Class Discussion *I modified this lab from The Illustrated Guide to Home Chemistry Experiments | To introduce the idea of reaction rates, I do a lab with Alka-seltzer tablets. They are cheap and easy to buy in bulk. Students take a mass measurement every 5 seconds for one minute. They also record the total time it takes for each tablet to dissolve fully. Station 1: Surface AreaStudents get 3 tablets, 1 whole, 1 broken into quarters, and one crushed in a mortar and pestle. Station 2: TemperatureStudents get 3 more tables and drop each in cold water, room temperature water, and hot water. Station 3: ConcentrationUse 3 different concentrations of HCl. I use 0.5 M, 1M, and 2M. After the lab, we come back as a whole group to discuss what we think it happening at the particle level. The more contact the particles can have with each other, the faster the Alka-seltzer will dissolve. |
| Affect of Concentration on Reaction Rates 1 day | Rate of Reaction POGIL | A great primer for notes, students analyze reaction rate graphs and determine how concentration affects the rate of a reaction. This is an AP-level POGIL, so you could skip it, but it has great graphing practice. |
| Factors Affecting Reaction Rates 1 day | Intro to Reaction Rates Notes | Referencing our rate of reaction lab, we take notes and learn how to calculate and graph reaction rates with molarity. |
| Review 1 day | Reaction Rate Vocabulary Practice Study Guide | If this is a stand-alone unit, go through your normal test prep routine. If it is, however, part of another unit, add some reaction rate practice to whatever you’re already doing. |
| Assessment | If you complete this as a mini-unit I suggest giving a short quiz. If it’s part of a larger unit, add a couple of questions to your test/exam. |
Looking for more?
The Chemistry Particle’s Guide to Teaching High School Chemistry, The Chemistry Particle
Chemical Kinetics with a Smartphone, ChemEdExchange
Investigating the Effect of Concentration on Reaction Time, ChemEdExchange
Reflections from Kinetics – Solidifying Why I Teach Method of Initial Rates AND Integrated Rate Laws, ChemEdExchange
