Question

Difficulty: EasyLaws of Chemical Combination (Conservation of Mass, Definite & Multiple Proportions)

When 10.0 g10.0\text{ g} of pure calcium carbonate (CaCO3\text{CaCO}_3) is strongly heated, it completely decomposes into solid calcium oxide (CaO\text{CaO}) and carbon(IV) oxide gas (CO2\text{CO}_2). According to the Law of Conservation of Mass, if 5.6 g5.6\text{ g} of calcium oxide remains in the container, what is the mass of carbon(IV) oxide gas released in grams?

Answer: 4.4 g

Answer

The mass of carbon(IV) oxide gas released is 4.4 g4.4\text{ g}.
According to the Law of Conservation of Mass, the total mass of reactants must equal the total mass of products in a chemical change. For the reaction CaCO3(s)CaO(s)+CO2(g)\text{CaCO}_3(s) \rightarrow \text{CaO}(s) + \text{CO}_2(g), the initial mass of 10.0 g10.0\text{ g} of CaCO3\text{CaCO}_3 must equal the combined mass of CaO\text{CaO} (5.6 g5.6\text{ g}) and CO2\text{CO}_2. Subtracting 5.6 g5.6\text{ g} from 10.0 g10.0\text{ g} yields 4.4 g4.4\text{ g} for the gas produced.

Step-by-Step Solution

1
Apply the Law of Conservation of Mass
Total mass of reactants (10.0 g10.0\text{ g}) = Total mass of products (solid residue + gas)
Mass cannot be created or destroyed in a chemical reaction.
2
Calculate the missing mass of carbon(IV) oxide gas
Mass of CO2=10.0 g5.6 g=4.4 g\text{Mass of CO}_2 = 10.0\text{ g} - 5.6\text{ g} = 4.4\text{ g}
Subtracting the mass of the solid product from the initial mass of reactant gives the mass of the gaseous product evolved.

Key Concept

Law of Conservation of Mass
Estimated Time:45s
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