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.
(2 points)

Explanation:

The scientist used the law of conservation of mass. This law states that mass is neither created nor destroyed in a chemical reaction. So, the total mass of reactants ($12.7\ g + 3.2\ g=15.9\ g$) equals the total mass of products.

Answer:

The scientist used the law of conservation of mass.