Question

A chemistry student combines 32 grams of one chemical and an unknown amount of another chemical in a closed system. A chemical reaction occurs and the mass of the products is 114 grams. How much of the unknown chemical was used in the reaction?

Answer 1

The reaction used 82 g of the unknown chemical.

The word equation is

Chemical 1 + Chemical 2 → Products

32 g + x g → 114 g

The Law of Conservation of Mass tells us the total mass of the reactants must equal the mass of the products. Then

32 g + x g = 114 g

x = 114 – 32 = 82

The mass of Chemical 2 was 82 g.