Calcium carbonate decomposes when heated to solid calcium oxide and carbon dioxide gas. The balanced equation is: CaCO3 (s) → CaO (s) + CO2 (g) Before this reaction was run, the reaction container, including the CaCO3, had a mass of 24.20 g. After the reaction, the container with product (and any unreacted reactant) had a mass of only 22.00 g because the CO2 gas produced did not remain in the container. What mass of CaCO3 reacted?

The mass of CaCO3 reacted is 5.00 grams

Explanation:

Step 1 : Data given

Before the reaction, the container, including the CaCO3, had a mass of 24.20 g

After the reaction the container with product had a mass of only 22.00 g because the CO2 gas produced did not remain in the container.

Molar mass of CO2 = 44.01 g/mol

Molar mass CaCO3 = 100.09 g/mol

Step 2: The balanced equation

CaCO3 → CaO + CO2

Step 3: Calculate mass of CO2

Mass of CO2 = 24.20 grams - 22.00 grams

Mass of CO2 = 2.20 grams

Step 4: Calculate moles CO2

Moles CO2 = mass CO2 / molar mass CO2

Moles CO2 = 2.20 grams / 44.01 g/mol

Moles CO2 = 0.0500 moles

Step 5: Calculate moles CaCO3

For 1 mol CaCO3 we'll have 1 mol CaO and 1 mol CO2

For 0.0500 moles CO2 we need 0.0500 moles CaCO3

Step 6: Calculate mass CaCO3

Mass CaCO3 = moles CaCO3 * molar mass CaCO3

Mass CaCO3 = 0.0500 moles * 100.09 g/mol

Mass CaCO3 = 5.00 grams

The mass of CaCO3 reacted is 5.00 grams