“These guys”: Sodium bicarbonate (baking soda). “Those guys”: Acetic acid (vinegar).
Minilab: mixing the two.

The minilab demonstrated the Law of Conservation of Mass, which states that matter is neither created nor destroyed in chemical reactions. Of course, if energy is gained or lost the amount of matter changes because of Einstein’s mass-energy equivalence equation so matter isn’t truly “conserved”, but any change would be to small to measure. Anyways, by measuring the masses before and after the experiment of both the baking soda and vinegar, we could prove the mass and the amount of matter was conserved. We then took the class’s average masses, and noticed that the amounts of solid and liquid before didn’t match the amount of product after. However, that is because gas escaped while we mixed the baking soda and vinegar, and we were able to account for that. These new calculations made the amount of solid and liquid before equal the amount of liquid solution and lost gas afterwards, and so we proved the Law of Conservation of Mass.

We then graphed the amount of solid to the amount of gas produced, and found a nearly linear relationship. We were able to conclude that the amount of gas produced was dependent on the amount of solid baking soda present in the reaction, so the relationship could be very effective in predicting the gas production from larger or smaller amounts of baking soda.

My picture

My picture

We can also conclude that this could happen with any pair of reactions, not just baking soda and vinegar, provided that there is a sufficient amount of the substance analogous to the vinegar in our experiment. If there wasn’t enough, not all of the other substance would dissolve, and it would produce less gas or some other precipitate than it should.