Hello again from the secret ACS demonstration laboratory! National Chemistry Week is fast approaching, so our next few posts will focus on fun activities you and you chapter can perform.
Our topic for this post is so amazing, it requires three demonstrations to adequately explain it: Carbon Dioxide! There are plenty more demonstrations where this came from, so stop by the American Chemical Society store and pick up What’s New, CO2? for more carbon dioxide demonstrations.
For our trifecta of carbon dioxide demonstrations, you will need:
- safety goggles
- thick gloves, preferably cryogenic liquid handling gloves
- lab coats
- a small aquarium or glass bowl
- a few blocks of dry ice
- tongs for handling the dry ice
- warm water
- dish detergent
- a straw
- bromothymol blue indicator
- a few candles
- a small glass
- a 5-gallon bucket
- a lighter
- a fire extinguisher
Use eyewear and a lab coat. Make sure your audience is at least 6 feet away. Do not handle dry ice without gloves. Use tongs to handle the dry ice. Make sure the room you are in is ventilated. Read the MSDSs for all materials before starting. Do not reuse the glass for drinking. Take all standard fire-safety precautions.
Experiment 1: CO2 plus water=Acid
- Fill your clear aquarium about a third full of warm water. Add 10-12 drops indicator dye. Explain to your audience that bromothymol blue is an indicator that detects the presence of acid. Ask them what they think will happen when you add the dry ice.
- Use the tongs to drop in a chunk of dry ice.
- Note the effect of dry ice on the dye. Explain how CO2 leads to increased acidity of water.
Experiment 2: CO2 plus fire = no fire
- Your clear aquarium should be full of CO2 by now. Light your candle(s). Explain to your audience that fire requires three elements: oxygen, heat, and fuel. Ask them what they think will happen when you take away the oxygen.
- Use your glass to “scoop up” some CO2. This works best if you hold the glass in the CO2 for a few seconds.
- “Pour” the CO2 onto the candle.
Experiment 3: How heavy is CO2?
1. Fill your 5 gallon bucket about a third full of warm water. Add a few chunks of dry ice and allow the bucket to fill with carbon dioxide.
2. Ask your audience what is in the bucket (correct answer: water and carbon dioxide). Ask them if they think it is lighter or heavier than air.
3. Dip your straw in your dish detergent (DO NOT INHALE), then blow soap bubbles into the bucket of CO2. Ask your audience why the bubbles float on the CO2.
Take a look at our video for our take on this. Feel free to comment about how you think it could be done better!