Amazing 20 foot geyser!
How does this happen? Carbon dioxide is pumped into soda and it wants OUT, as you can see/hear anytime you open a new bottle of soda -that hissing sound is the CO2 escaping. A piece of Mentos candy has microscopic pits all over it. These are called nucleation sites - places where CO2bubbles can grab onto. A ton of CO2 bubbles will form all over each Mentos candy as they sink to the bottom (we put in 8 candies) . The bubbles seed more bubbles as they rise & soon there is a raging foam in the bottle - pressure builds & the result is a huge geyser! Almost all of the soda comes shooting out of the bottle! I do this every year with my students & I never get tired of the looks on their faces - priceless! I use this experiment to teach the scientific method: making observations, asking questions, making hypotheses, recording data, making conclusions.
Using this tube has made it much easier for me to get out of the way before the geyser erupts:
There are so many questions you can address in this activity/ so many ways to change the variables, here are some of the questions I've investigated with my kids:
Does it work with fruit Mentos? (yes)
Does it work with Sprite? (yes)
Does it work with soda that has been sealed but left in my science closet for a year? (no!)
Does it work with Life Savers? (no!)
I like to have my students write down 2 variables they would like to change and then I choose a couple of the experiments to try each year.
I also use this experiment to teach solids (Mentos), liquid (soda), gas (carbon dioxide) - fun fun fun & educational too!
Hope you had a wonderful Mother's Day!