It is well known that when a Mento is dropped into soda, something cool happens. But, what actually happens?
The dissolved CO2 in the soda is constantly looking for a place to accumulate and form a bubble. But, bubbles don’t form spontaneously because the water molecules keep the CO2 molecules trapped in its weak structure (connected by hydrogen bonds).
When a Mento is dropped into the soda, the CO2 molecules gather in small craters on the Mento, which can also be called nucleation sites. When enough CO2 molecules gather in a nucleation site, a bubble forms and is lifted up. Using the balloon, these bubbles can be captured, and the amount of CO2 can be measured.
The following experiment was created to show the effect of the amount of Mentos (hence, more surface area and nucleation sites) on the volume of CO2 released by the soda.
Step 1: Defining the Problem for Investigation
Question: How does the number of Mentos affect the amount/rate of CO2 being released from soda?
The independent variable in this experiment is the number of Mentos put into a soda can.
The dependent variable is the amount of CO2 released from the soda and the rate at which it is released, as measured by the width of the balloon containing the CO2.
Hypothesis: If a certain amount of Mentos are dropped into a container of soda, then the container with the most Mentos dropped into it will produce the most CO2 at the fastest rate. This will happen because the dissolved CO2 will provide the most nucleation sites to come out of the solution.
- Surrounding temperature
- Type of soda used
- Amount of soda used per trial
- Type of Mento used
Step 2: Materials
This experiment should be conducted somewhere where the ground and wall coincide (this allows the metric tape measure to be taped to the wall), and where the temperature is fairly constant.
- Safety glasses
- 1 Beaker
- 1 12-pack (cans) of soda
- 2 Sticks of Mint Mentos (37.5 g/ 1.35 oz)
- 3 Balloons
- 6 Rubber bands
- Metric tape measure
- Duct tape
- Glass bottle or reusable plastic bottle with a small top
- Permanent marker
- Camera (optional)