Question

Use the chemical equation to complete the activity.

2Cu +S -> Cu2S

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, explain the law that the scientist used to predict that the product of the reaction
would be 15.9 grams of copper sulfide.

12 pointe )

Answer 1

The scientist used the law of conservation of mass. It states mass is neither created nor destroyed in a chemical reaction, so the product mass equals the sum of reactant masses (12.7 g + 3.2 g = 15.9 g).