Law of Conservation of Mass Investigation

Today we investigated mass and weight in the Conservation of Mass Investigation. In order to complete the lab investigation we needed 1-2 packets of pop rocks, 2 balloons, 2 twenty ounce soda bottles (one empty, one full), 1 tsp. of baking soda, 50mL of vinegar, a funnel, graduated cylinder, and a plastic spoon. There were two tests to complete, the Pop Rocks test and the Baking Soda/Vinegar test. Our problem was: What will happen to the balloon when the Pop Rocks are dropped into the bottle? Our hypothesis was: If we put the balloon on the bottle and drop the Pop Rocks, then the balloon will inflate because of the carbon dioxide in the Pop Rocks that will be released.

We began with the Pop Rocks test by pouring out half a packet of Pop Rocks into one of the balloons. First we had to stretch the balloon to make it more flexible. Then once the balloon was filled we attached the balloon to the soda bottle, but we did it in a way so that the balloon was at the side of the bottle and we could control went to drop in the Pop Rocks. Like this:

Then we poured it into the bottle, and watched. Basically what happened was the balloon stuck upright, and the part of the balloon covering the opening in the bottle filled up slightly. The Pop Rocks fizzed and dissolved in the soda. When we looked around, compared to other groups' balloons, ours had not been filled up much at all. It may have been because we were only able to use half the packet of the Pop Rocks, or maybe because we did not stretch our balloon very long. Then we got the idea to shake our bottle from one of the other groups, it maybe released the carbonation from the coke because the balloon started inflating a lot more. Soon there was only two inches of balloon not inflated. It looked somewhat like this, but the balloon was much smaller:



Then we did the baking soda and vinegar test. We went through pretty much the same procedures, except we used the empty bottle and filled it with 50mL of vinegar. Then instead of Pop Rocks, we filled the balloon with baking soda. Then we attached the balloon onto the bottle and poured in the baking soda. The second the baking soda touched the vinegar it started bubbling and fizzing. In less than three seconds the vinegar-baking soda had bubbled up to the top of the bottle and the balloon had fully inflated. But, the reaction soon ended, just as quickly as it happened. The vinegar mixture bubbled back down to the bottom of the bottle, and the balloon deflated slightly.


My hypothesis was supported, because it was pretty much what happened. I did not know all the details of how the balloon would be inflated, but I knew carbon dioxide was inside of the Pop Rocks, and figured it would end up inflating the balloon. Now I know exactly how it worked. When being made, Pop Rocks are boiled at a very high pressure with carbon dioxide, and the end result is tiny bubbles of carbon dioxide compressed at 600 PSI inside the candies. So when they are opened up or dissolved, the carbon dioxide is freed. So when put in the bottle of soda, the Pop Rocks were dissolved and the carbon dioxide went up into the balloon. Something else that I left out in the hypothesis was that the soda also contributed to the inflation of the balloon. But after some research, I found that the Pop Rocks actually released carbon dioxide from the soda. So the soda also helped inflate the balloon.

Something I thought was interesting was that the Pop Rocks and soda test did not show a chemical reaction, but a physical reaction. The reason is being that the soda is just dissolving the Pop Rocks which releases its carbon dioxide, and there is no real reaction.