Dry calcium carbonate is placed in a crucible and heated over a flame. After cooling, the mass of the crucible and contents is determined. We are given the recorded data. Mass of crucible equals 14.01 grams. Mass of crucible and calcium carbonate equals 64.05 grams. And mass of crucible and product after heating equals 42.05 grams. The reaction that occurs by heating the calcium carbonate produces both calcium oxide and carbon dioxide gas. The type of reaction that occurs is a (A) double displacement, (B) combination, (C) decomposition, (D) substitution, or (E) addition reaction.
Calcium carbonate, or CaCO3, is a metal carbonate. Metal carbonates, in general, decompose or break apart when heated, to form metal oxides and carbon dioxide. In this question, solid calcium carbonate when heated decomposes or breaks apart to form the metal oxide calcium oxide, which is a solid, and carbon dioxide gas. This question only asks us what type of reaction is occurring. So, we do not really need the mass data that has been given to us.
The setup for this decomposition reaction is shown in the diagram. A crucible containing the solid to be heated is placed on top of a wire gauze, which is resting on a tripod stand. The solid in the crucible is heated with a Bunsen burner flame. Crucibles are usually made from a ceramic material or a metal because these materials can withstand very high temperatures.
After enough heating, the calcium carbonate breaks apart to release CO2 gas into the atmosphere. And a white powder, calcium oxide, is left behind in the crucible. Because one reactant is forming more than one product, this is a decomposition reaction.
So, the answer is (C) decomposition.