When it comes to chemistry and physics, your kitchen is the perfect place to experiment with different kinds of reactions. Here’s one of our favorites. You wouldn’t want to eat it, but it’s a heck of a lot of fun. For others great ways to do science in the kitchen, turn to page 152 of UNBORED.
Because ethanol, a flammable liquid that can be produced by fermenting sugar (processed from corn, or from unprocessed “biomass”) with yeast, emits cleaner emissions than gasoline, ethanol- fueled vehicles are becoming more common. So here’s an ethanol-related puzzler: If we combine yeast and sugar, how can we tell if the yeast is breaking down the sugar through fermentation?
As yeast eats whatever sugar it finds in the bottle, the sugar will break down into not only ethanol, but carbon dioxide. So we can solve our ethanol puzzler through a process that allows us to detect whether or not carbon dioxide has been produced. This will tell us whether the fermentation process is taking place.
The following fermentation-in-a-bottle experiment won’t permit you to directly see etha- nol, because if any is produced, it will mix with the water in the bottle. However, at least you’ll be able to measure how much (if any) carbon dioxide is produced when you combine yeast with either processed sugar or an unprocessed biomass.
- 3 clean 20 oz. plastic bottles. Save the caps.
- 3 tablespoons of yeast
- 4 tablespoons of a sugar—whether it’s corn syrup,
table sugar, or a cola drink.
- 4 tablespoons of an unprocessed biomass: e.g.,
dried, ground-up leaves; dried, ground-up grass;
dried, ground-up cornhusks; or sawdust.
- Plenty of warm water
- Several 9″ balloons—use non-latex balloons if you
are allergic to latex.
- Permanent marker
- Optional: Funnel
Formulate a theory
Will enough carbon dioxide be produced to inflate any of the balloons? If so, which balloons? Which balloons will inflate the most?
1. Add 1 tablespoon of yeast to each bottle.
2. Mark the first bottle “CONTROL” and set it aside.
3. Mark the second bottle “PROCESSED SUGAR,” and add 4 tablespoons of a sugar to it.
4. Mark the third bottle “BIOMASS,” and add 4 tablespoons of an unprocessed biomass to it.
5. Fill each bottle halfway with very warm (but not hot) water. Screw its cap on tightly and shake the bottle to mix the ingredients thoroughly.
6. Now remove each bottle’s cap and replace it with a balloon, pulled firmly over the spout. (You really only need three balloons, but we’ve sug- gested you collect several in case you tear one.)
7. Observe, and record the data from your results.
8. Pour the (gross) contents of the bottles out. Recycle or reuse the bottles.
If your theory was incorrect, ask yourself why. And then start the process over again—that’s how science works.
KITCHEN OBJECTS EXPERIMENT
Not all kitchen experiments have to do with mixing up food. Here’s a fun science experiment that dates back to Benjamin Franklin — but which uses objects found in today’s kitchen, including cans of soda pop, a ball of aluminum foil… and an electric flyswatter.
NOTE: We didn’t make this video. We just think it’s cool.