BEAM: Soda Mentos Reaction Lesson

1. BEAM: Soda Mentos Reaction Lesson Siddarth Krishna Week of 3/11/13 - 3/15/13

2. Overview & Goals • Use scientific reasoning to figure out what properties of the soda, mentos, and gas released cause the mentos-soda reaction to happen • Have fun playing with soda and mentos • Throughout the lesson: don’t give away answers! Let the kids guess and reason

3. Agenda • Introduction: What is soda? • Investigating the Gas: Mentos-Soda Demo • Investigating the Soda: What works and why • Investigating the Mentos: Surface properties

4. Introduction • After asking what they think soda is made up of, tell them it’s mainly water, sugar, and fizz. Talk about what they think fizz is. • Then do the mentos-soda balloon demo as a group, looking at properties of the gas released • Then, break into groups for the experimentation (Mentos, Soda) modules while mentors facilitate

5. Module 1: Gas Investigation • For the kids to determine what is released by the reaction • Demo: (outside, in a group): Blow up a balloon using mentos • Put ONE mento into balloon (all the way in) • Fix balloon’s mouth over soda bottle’s lip -Then push the mento into the balloon. Hold balloon vertical, with a hand on the lip of the bottle! • Liquid will shoot into balloon. Let it drain, then carefully take balloon off and tie it off • Might take two tries…

6. Module 1: Gas Investigation (ct’d) -Ask the kids what they think happened! Don’t just tell them it was CO2 gas released. Some might already know it’s CO2, but ask them how they could prove it • Blow up another balloon to the same size with air. Ask kids if they think the CO2-balloon is the same as the air balloon. Then show them how the CO2 balloon falls faster, and ask them why they think that happened • Main point: the gas released by the rxn is not air, it’s something else. (At the end, we’ll tell them it was CO2)

7. Module 2: Soda Investigation • Divide students into 2-3 groups • Give them the individual ingredients of soda(club soda, sugar water, soda), let them experiment • Goal is to figure out what property of the soda causes the reaction (fizz, not sugar) • Pour liquids for them (~150 mL in cups) • Help them make an experimental plan and interpret their results, but don’t give away answers • Encourage them to be creative! They can try multiple mentos, water-soda mixtures, etc

8. Module 2: Soda Investigation (ct’d) • They can write down observations, conclusions, etc on paper • Note: Sugar into soda causes the reaction too – but students shouldn’t conclude it’s just the sugar that causes it • Also: After mentos rxn is over, the soda will be flat and won’t do the rxn again. The kids should notice this • Also: The reaction works better with diet (the sugar sweetener is involved), but we are ignoring that effect by not using diet

9. Module 3: Mentos Investigation • Looking at what property of mentos causes reaction to happen • I made “smooth” mentos by microwaving them in water and then letting them dry. They won’t work in the reaction. • The kids will see that these don’t work, and can use magnifying glasses to see the smooth vs rough surfaces • Answer: Rough mentos surface are nucleation sites for CO2 bubbles to form and then escape • Let them figure out on their own! It’s the surface, not some chemical in the mentos, that causes the rxn.

10. Conclusion • Briefly discuss with students what they learned- what they think is going on in the mentos-soda reaction and why. Their pieces of paper should come handy. • Tell them the answer: The rough mentos surface helps the CO2 (fizz) in the soda form bubbles and escape as a gas!

11. Reminder: Materials • ~20 Cups (for kids to experiment in) • 3 Packets of regular mentos • ~4 Balloons, two 710 mL Soda bottles (Gas Investigation) • Two 2L Soda bottles, 1L sugarless Club Soda, plain sugar (Soda Investigation) • Magnifying Glass + 1 packet of Microwaved mentos (for Mentos Investigation)