Class began with students receiving back their mini-quiz from last week which we reviewed together as a class. Students were reminded that all work from lessons 70-73 (chapter 13) must be turned in no later than tomorrow for credit. After the review, students voted on one of two options:
- Continue forward with Lesson 74: Toxicity
- Conduct an experiment focused on the combustion reaction
Students elected to learn about the combustion reaction, so we reviewed the combustion of propane and balanced the equation, then carried out an experiment in which a candle (made of paraffin wax, another hydrocarbon) is combusted under a bell jar. We timed how long the candle burned for, and also measured the amount of oxygen and carbon dioxide in the room (before combustion) and under the bell jar (after the candle extinguished.
Next, we wrote the chemical equations for combining hydrogen peroxide and bleach (producing oxygen) and for combining baking soda and vinegar (producing carbon dioxide). We evaluated the effect of combustion in the presence of excess oxygen or carbon dioxide, measuring how long the candle burned as our endpoint. Class notes are provided below.
We will return to our regularly scheduled programming (lesson 74) tomorrow!