Question

2Cu+S->Cu2S
Copper reacts with sulfur to form copper sulfide as shown in the equation. A scientist adds 12-7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide. In two sentences explain the law that the scientist used to predict the product of the reaction would be 15.9 grams of copper sulfide

Answer 1

The scientist used the Law of Conservation of Mass, which states that mass is neither created nor destroyed in a chemical reaction. Therefore, the total mass of the reactants (12.7 grams of Cu and 3.2 grams of S, totaling 15.9 grams) should equal the total mass of the products, predicting that 15.9 grams of copper sulfide would be formed.