Day 5: Elephant Toothpaste

Where the foam comes from: all that oxygen gas would normally just float away into the room. But add dish soap, and every bubble of oxygen gets trapped in a soap film. Multiply that by millions of bubbles forming at once — and you get a tower of foam climbing out of the bottle.

Two strengths of peroxide today:

• 3% — what you'd find in your bathroom medicine cabinet at home. Safe enough that people put it on cuts.
• 6% — sold at beauty supply stores to bleach hair. Twice the concentration. Twice the available peroxide for the reaction.

You'll run the experiment with both. The 6% reaction will look noticeably bigger. That's the math you'll work out in a few minutes.

⚠️ Safety first — non-negotiable:

• Safety goggles on before you touch anything.
• Gloves on. The 6% peroxide can irritate skin and bleach clothes.
• Don't touch the foam. The reaction releases a little heat and the foam can contain leftover peroxide.
• If anything splashes on skin or eyes, rinse with water immediately.
• The peroxide goes in only when you're outside, at the tray. Never in the classroom.

• 1 prepped plastic bottle (black line marks your water level — easy)
• 2 packets of active dry yeast (one per run)
• Warm water (in a pitcher at your table)
• Dish soap
• Food coloring
• 3% hydrogen peroxide (at the outdoor station)
• 6% hydrogen peroxide (at the outdoor station)
• Plastic tray (outside — catches the foam)
• Safety goggles + disposable gloves

1. Add warm water up to the black line on the bottle. Don't go over.
2. Dump one full packet of yeast directly into your bottle.
3. Shake gently to mix.
4. Now warm the bottle in your hands for 2 minutes. The yeast is alive — it needs body-temperature warmth to wake up. You'll start to see tiny bubbles. That's it activating.

1. Set the bottle down.
2. Drip several drops of food coloring along the inside walls — this creates color streaks in the final foam.
3. Add 1 squirt of dish soap (about a tablespoon).
4. Swirl gently to mix. Don't shake hard — you don't want the yeast to lose its mojo.

Take your bottle outside to the experiment station. Goggles and gloves on.

1. Set your bottle in the center of the tray.
2. Pour in 1/2 cup of 3% hydrogen peroxide.
3. Step back immediately.
4. Watch.

On your 📋 Reaction Lab Sheet, record: how tall did the foam climb? How long did the reaction last? How warm did the bottle get? Sketch the shape.

1. Bring your bottle back inside. Rinse it out with warm water at the sink. The foam dissolves and rinses easily.
2. Dump in your second yeast packet.
3. Add warm water to the black line. Shake.
4. Warm in your hands again — give it 1–2 minutes to activate.
5. Add food coloring + 1 squirt of dish soap. Swirl gently.

Back outside. Goggles and gloves on. Same drill — but now you pour 1/2 cup of 6% hydrogen peroxide.

Step back. Watch.

Record on your Reaction Lab Sheet alongside Round 1. Same columns, same measurements — that's how you'll compare.

You just tested this for real.

Round 1 used 3% peroxide. Round 2 used 6% — twice the concentration. That means twice as many peroxide molecules in the same half-cup. Look at your Reaction Lab Sheet. Was the Round 2 foam roughly twice as tall as Round 1? More? Less?

On your 📋 Reaction Lab Sheet, answer:

• How tall was your Round 1 (3%) foam? How tall was Round 2 (6%)?
• What's the ratio — Round 2 height divided by Round 1 height? Is it close to 2?
• If you used 12% peroxide (industrial concentration), what would you predict?

If your ratio isn't exactly 2, that's normal. At higher concentration the reaction also goes faster and gives off more heat — both of which affect how much foam ends up trapped vs. escaping. Real chemistry isn't always perfectly clean.

If you doubled the yeast instead of the peroxide, would you get more foam — or just faster foam? Discuss with your group, then write your prediction.

(You'll see this idea in the next section.)

Variables you could try:

• Two yeast packets instead of one — more catalyst, more foam? Or just faster foam? (Remember Part II of the math.)
• Cold water instead of warm. Predict before you test.
• Less soap — half a squirt. Foam-trapping changes.
• Skip warming the bottle in your hands. Does the yeast still work? How well?

• Chemical engineer — designs industrial chemical processes. Every plastic, fuel, detergent, and medication you've ever used was scaled up from a small reaction by a chemical engineer running this exact math.
• Rocket propulsion engineer — controlled chemical reactions are literally rocket science. SpaceX uses concentrated hydrogen peroxide (~98%) as part of its rocket engine systems. Same molecule, way more dangerous.
• Pharmaceutical chemist — every drug is a reaction. Getting the ratios right is the difference between a working medication and a useless or toxic one. Companies: Pfizer, Genentech, Amgen (all have California labs).
• Cosmetic chemist — beauty supply 6% peroxide (what you used today) is also what hairdressers use to lighten hair. Same chemistry, slower reaction.
• Forensic chemist — identifies unknown substances at crime scenes using reactions like the one you ran. Most county crime labs hire these every year.
• Biochemist — studies catalase (the enzyme in yeast you used) and other enzymes that run every reaction inside your body. Path to medical research.

Path note: Chemistry and chemical engineering are everywhere in Southern California — Cal Poly Pomona, UC Irvine, USC, UCLA, Cal State Long Beach all have programs. Community college first (Santa Ana, Cypress, Orange Coast) saves money and transfers cleanly into the same degrees.