MENTOS + SODA = ?
One of the first activities I used to use with my Chemistry and Physical Science classes was the Mentos and Diet Coke experiment. Each student would select a variable to test outside. We would combine our class results, and students would read articles and look at the Myth Busters’ video. Surprisingly we would find information not addressed by the Myth Busters. The students loved the activity—very motivating! And it is the perfect introduction to argument from evidence. I think this could easily be used with middle school students. Caution the students to wear goggles and aprons, and not to ingest the Mentos and soda. (Of course one of mine did—soda shot from his nose, but no other ill effects.) You will have your students hooked on science the rest of the year!!
PROBLEM: Why does diet soda erupt violently when Mentos candy is added?
PRE-LAB DEMONSTRATION: Compare the amount of gas released in a diet soda and club soda with Mentos (use one liter bottles). Drop in the Mentos, and. Perform this demo in a plastic storage box to catch any mess. MATERIALS: 1-1 L Diet Coke and 1 1-L Club Soda/class and one Mentos per bottle. One plastic storage box or aquarium. Measure the height of each plume to compare.
HYPOTHESIS: (Select one variable to explore related to the above problem. Write a hypothesis related to your variable.) You and your partner(s) will design an experiment to test your hypothesis.
SAFETY: Goggles and aprons must be worn during this activity.
MATERIALS: (provided by teacher)
- Mentos candies
- Other candy
- Meter stick
- Test tube (for adding Mentos to bottle)
EXPERIMENTAL DESIGN: (What you plan to do listed in order)
RESULTS: (What happened)
CONCLUSIONS: (Do you accept or reject your hypothesis, and why or why not)
You and your partner will share your experiment with the class. State briefly what you tried, what your results were, and what you might do differently next time. Decide who will do what, so you will be ready when it’s your turn.
1.) How did our class results compare with what the Myth Busters found?
2.) After watching the Myth Busters video clip, what would you do differently next time?
3.) Is there anything else you think the Myth Busters should have tried?
4.) Based on our class results, the video, and the attached articles, create an argument for what you think causes Mentos to erupt in Diet Coke.
____I included the independent and dependent variables in my hypothesis. (5 pts.)
_____I explained my procedure so well, my 10-year-old brother could understand it. (10 pts)
_____I measured or accurately estimated the height the soda achieved in my results (5 pts.)
_____I accepted or rejected my hypothesis and explained why in my conclusion. (5 pts.)
_____I answered each question completely and thoroughly. (10 pts.)
you can download the questions and scoring guide here: Download Now
The pre-lab demonstration is to show the students that there is a difference between the diet soda and just carbonated water. The diet soda will erupt to a height of about 4 feet, but the club soda will just overflow. I had trouble finding a 1-L diet soda, so I used 24 oz. Diet soda, and it still erupted much more than the 1 L Club Soda.
Explain this lab to the students several days in advance, as they may want to bring items to use in this lab. I purchased extra diet soda, just in case the students did not plan well or forgot their materials, but most remembered.
The students performed a variety of experiments. I had them approve their idea with me first. Some of our results differed from the Myth Busters. It gave us good material for a post-lab discussion!
I downloaded the following article from the Internet at the web site below, that give an explanation for why the diet soda erupts.
http://www.us.mentos.com/ Mentos web site. Go to FAQ and scroll down.
Caution students not to ingest Mentos and diet soda. The deaths reported seem to be a myth, but I’m quite sure the student would regret his/her actions if he/she tried it! I had a student who tried it, and foam shot out his nose!