Science Buddies: "Ask an Expert"

So... I found an idea on my science teachers website (I am in eighth grade) that talks about testing variables to see what factors affect how quickly soda loses its carbonation. I decided to get three Mexican Coca-Colas from Walmart and put one in my garage, one in my fridge, and one in the kitchen to see which location made that Coke lose its carbonation fastest. My hypothesis is that if I increase the temperature, then the carbonation will decrease (basically, the one in the garage will lose its carbonation the fastest because thats where its hottest). So my teacher said my idea was cool, but I need to figure out a way to measure the amounts of carbonation in the soda every day. For the experiment, I will unscrew the lids, but set them on the top of the drink. I thought that every day, I could pour 1/2 inch of soda into a measuring cup, and measure the amount of "fizz". My teacher said that that wouldn't work because a drink might bubble whether it has carbonation or not. HELP!!! I don't know a good way to measure the carbonation every day. I have researched it on google a lot, but...

Hello macaroni3299! This sounds like a very interesting project.

I've done a few searches, and I came up with a few easy ways; hopefully one of them will work for you.

The first is surprisingly simple; since carbon dioxide is heavier than air, a digital scale (even a bathroom scale should work fine) can measure its weight. As carbonation is lost and the soda goes flat, the overall weight of the soda and can/bottle will decrease. If you keep the soda covered with the lid, there shouldn't be a problem with dust or other stuff entering the bottle and changing the weight. So, if you weigh the soda before opening and every time that you want to check the carbonation, the decrease in the weight should tell you how much carbonation was lost.

Another way that I found was more complicated, but would likely give you more accurate data. If you had trouble with the first way, this one would work better. You would need some kind of seal; it could be as simple as some clay or silly putty, and a rubber seal would work too. Tape might work, but duct tape would be much more secure than Scotch or masking tape. What you would need to do is place some kind of tube (clear vinyl or rubber tubing is cheap online or at Lowe's) and seal it tightly to the top of the cap. Then, you'd need to place the other end of the tube in a tub of water and beneath a measuring cup of some sort (the cup would also be under the water, and filled with water). As carbonation exited the soda, it would be pushed down the tubing and into the measuring cup. The level of carbon dioxide in the cup would show how much carbonation had been lost.

I hope one of these methods works for you! If you're confused, or have trouble, don't hesitate to ask.

Good luck!

Hi macaroni3299,

The above Expert gave you some pretty good ways to measure carbonation. The only thing I would suggest is to strive for the second one, as I also feel it'd be more accurate. The first method would require a pretty sensitive scale, and I don't think a bathroom scale would cut it, as a typical one measures to the nearest pound, whereas a regular Coke bottle goes by ounces.