Lesson: Conservation of Mass

Antoine Lavoisier was one of the first scientists to state the law of conservation of mass. When he heated a sample of tin and air in an airtight flask, tin reacted with oxygen in the air to produce tin oxide. Did the mass of the flask and its contents increase, decrease, or stay the same because of this reaction?

A wet 43.2 g sample of copper sulfate heptahydrate is heated until only copper sulfate remains. The mass of the water lost is 34.1 g. What is the mass of the copper sulfate?

A 13.5 g sample of calcium carbonate is heated until it decomposes completely and 7.6 g of calcium oxide is produced. What is the mass of carbon dioxide produced?