Wednesday, May 9, 2012


Today we finally launched our Mentos and Diet Coke experiment.  We learned some about atoms and chemical reactions then planned out an experiment.  Here is what we learned (recorded via interview):

First we learned about atoms.  Everything is made out of atoms.  When there is a chemical reaction, atoms don't change, they just reorganize.  Signs of chemical reactions are heat, cold, change of color, and a new substance being formed.

The reason Mentos and Coke explode is because lots of bubbles form quickly.  Mentos and Coke react especially well because of the chemicals that are present in both.  The release of bubbles is not thought to be a chemical reaction.

For our experiment we decided to test which amount of Mentos or other substance caused the greatest expulsion of Coke from a bottle.  Eli and Grace expected 5 crushed Mentos would do the best because there was more stuff and more exposed surface area to encourage reaction.  Sophia expected the 5 regular Mentos would do the best because when crushed, some material might be lost.
 Materials gathered and ready to begin.

Our basic procedure was:
1) Tilt (except for one of the treatments) and open small Coke bottle,
2) Add substance,

3) Wait for reaction then measure remaining Coke using graduated cylinder,

4) Record results.

Here are our results (note that we only conducted one trial for each treatment of the variable to save on materials):

Independent variable:                     Dependent variable:
What we put in                               Amount of Coke left (mL) and observations
1. Half a Mento                              157, Lots of bubbles
2. 1 Mento                                      151, Same
3. 1 Life Saver                                355 (none expelled), Very fizzy for a long time
4. 5 Mentos                                    119, 3 Mentos blasted out
5. Baking Soda                               279
6. 5 Crushed Mentos                      139, Lots blasted out
7. 5 Mentos (Bottle Facing Up)     135, Coke may have fallen back in
8. 1 Crushed Mento                        211
9. 5 Mentos in large Coke bottle (just for fun)
The 5 Mentos (Bottle Facing Up) Treatment

The 5 Mentos expelled the most Coke. This is because there were a lot of them (more reaction material) and they were heavier so didn't blast out as much.

Eli was surprised the crushed Mentos didn't expel the most.  We think it may be because so many were blasted out.  Or, it may be because some material crumbled off and was lost in the crushing process.

Eli also notes that it is interesting that the one Mento and half Mento did about the same.  This may be because that the smaller size was offset by the relatively greater surface area.

While we didn't get a lot of significant results from it, the 5 Mentos treatment with bottle facing up looked the nicest.

At the end, for fun, we tried 5 Mentos with a large Coke bottle.  It was pretty cool.  Mama thinks it might be interesting to do this test by measuring the height of the Coke geyser.  Eli thinks it would be neat to do this with a lid on the bottle that has a small hole drilled in it to produce a taller, thinner stream.  Grace wonders if we could find a way to catch what comes out and measure that instead.  Sophia thinks an experiment with vinegar and baking soda would be worth trying.

Sophia, Grace, Eli (interviewed by Joey with a cameo by Juliana)

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