Catalase, or enzymes, drastically increases the rate of hydrogen peroxide decomposition. This lab shows how catalase added to hydrogen peroxide leads to the release of oxygen, boiled catalase is denatured, and the presence of catalase in living things can lead to the breaking down of hydrogen peroxide in the body. In the lab it was shown that the natural decomposition hydrogen peroxide is slower than decomposition taking place with the addition of enzymes. If hydrogen peroxide was required to decompose naturally, life could not survive. The addition of catalase increases this decomposition rate allowing life to continue.
In chemistry you can almost never have the perfect environment and perfect accuracy to receive the perfect result. Each experiment, though done multiple times, will almost always have different results. In our experiment there were many such sources of error. The Magnesium metal, when poured into the HCl acid, left its residue of the measuring boat so not every single particle of Mg was used which, in turn, might have caused a minute difference in the final result. Another factor is that we might not have had exactly 50 ml of HCl. Its cohesive properties left residue on the sides of the beaker which might have caused a small difference. The graduated cylinder also is only exact to the ml which leaves a 1% margin of error. Also, the hydrogen gas release condensed around the sides of the beaker which might have also had a change in the mass of the final product.