Copper (Cu) reacts with sulfur (S) 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 (Cu2S). In 1-2 sentences, How would you explain the law that the scientist used to predict that the product of the reaction would be 15.9 grams of copper sulfide.

Question

Copper (Cu) reacts with sulfur (S) 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 (Cu2S). In 1-2 sentences, How would you  explain the law that the scientist used to predict that the product of the reaction would be 15.9 grams of copper sulfide.

GPT-4o mini · Answer

The scientist used the law of conservation of mass, which states that in a closed system, the total mass of reactants must equal the total mass of products. Since all the copper and sulfur react completely, the combined mass of the starting materials (12.7 grams of Cu and 3.2 grams of S) amounts to 15.9 grams, which should match the mass of the copper sulfide produced.