When dissolving limestone weighing 1 kg in hydrochloric acid, CO2 was released

When dissolving limestone weighing 1 kg in hydrochloric acid, CO2 was released in a volume of 150 ml. What is the mass fraction of CaCO3 in this limestone.

1. According to the condition, the reaction proceeds:

CaCO3 + 2HCl = CaCl2 + H2O + CO2 ↑;

2. Let’s calculate the chemical amount of released carbon dioxide:

n (CO2) = V (CO2): Vm = 0.15: 22.4 = 0.0067 mol;

3. Set the amount of calcium carbonate:

n (CaCO3) = n (CO2) = 0.0067 mol;

4. Find the mass of carbonate:

m (CaCO3) = n (CaCO3) * M (CaCO3);

M (CaCO3) = 40 + 12 + 3 * 16 = 100 g / mol;

m (CaCO3) = 0.0067 * 100 = 0.67 g;

5. Let’s calculate the mass fraction of carbonate in limestone:

w (CaCO3) = m (CaCO3): m (limestone) = 0.00067: 1 = 0.00067 or 0.067%.

Answer: 0.067%.