This lab introduces applied Stoichiometry. Students should know how to calculate formula mass, convert between grams and moles, balance equations, and use mole ratios.
If they've learned conversions but haven't encountered stoichiometry, this is a great way to introduce it.
You'll need (alternative supplies below! you don't NEED lab supplies other than citric acid)
Citric acid; buy this in cooking supply stores or online. Less than 100g needed
Baking Soda; less than a half-cup or 100 g
Balance; able to weigh out to the nearest tenth of a gram.
Calculator (students can easily do the math w/out one)
2 weighing dishes
Small beaker or flask.
IF YOU DO NOT HAVE THESE:
1. No balance? Use a kitchen scale that measures grams. Use twice or even three times as much of both chemicals to get an accurate measurement if your scale isn't accurate with small amounts.
2. You don't need a beaker or flask. A clear plastic cup works fine.
3. No weighing dishes? Use a piece of paper with the edges bent up to make a "tray" to measure out the powder without making a mess.
4. No graduated cylinder? A cup of water works just fine as long as you can pour out a small amount at a time.
To add content, you can include pH paper and have students test the Citric Acid and Baking Soda and then the solution over the course of the experiment.
Adding water with dish soap in it will create lots of bubbles. There should be plenty of leftover mix at the end. Put it in a cup, put that in the sink, and add water and dish soap. Bubbles!