The scientists 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) must equal the mass of the products, leading them to predict that the total mass of copper sulfide formed will also be 15.9 grams.
Copper(Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientists add 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 scientists expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2 S). In 1-2 sentences, explain the law that the scientists used to predict that the product of the reaction would be 15.9 grams of copper sulfide.
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