The conservation of mass means that in a chemical reaction, the mass before the change and the mass after the change is equivalent. Matter is conserved in a chemical reaction. I know this because it has been proved by many experiments, and is explained by the Law of Conservation of Mass.
In our mini lab, there was a predictable relationship. The mass of the reaction was conserved, but we lost some mass in the form of gas, which was expected. This would apply to any substance, including the possibility that mass was “lost” as a result of gas produced, even though it was still there, but was simply not included in the mass of the beaker contents after the reaction.
Our point was somewhat good. It was close to the line of best fit, but slightly under. We should have lost .4256 grams of gas for each gram of solid. We discovered this while graphing our class data. If 5 grams of solid was used, 2.2114 . I came to this conclusion by using the equation for the line of best fit for the class data (.4256x+.0834), and plugging in 5 for X. If 5 grams of gas was produced, 9.8231 grams of solid was used. I found this by using the equation x/.4256+.0834.