A chemist decomposes 100.1 grams of a substance into 12.1 grams of carbon and 40.0 g of magnesium. The only other product of the decomposition as oxygen, but the gas escaped from the setup. What was the mass of oxygen gas that escaped?

1 Answer
Dec 11, 2015

The mass of oxygen that escaped is #"48 g"#.


The law of conservation of matter requires that the mass of the reactants is the same as the mass of the products in a chemical reaction.

The compound being composed had a mass of 100.1 g. To determine the amount of oxygen that escaped, subtract the sum of the masses of carbon and magnesium from 100.1 g. The difference will be the mass of the oxygen.

#100.1 "g"-(12.1 "g" + 40.0 "g")="48 g"#

The mass of oxygen that escaped is #"48 g"#.