When firing 100 g of limestone, 40 g of carbon monoxide 4 was obtained
When firing 100 g of limestone, 40 g of carbon monoxide 4 was obtained, considering that all calcium carbonate decomposed, find its percentage in this limestone sample
1. Let’s compose an equation describing the decomposition of calcium carbonate:
CaCO3 = CaO + CO2 ↑;
2. Calculate the chemical amount of carbon dioxide produced:
n (CO2) = m (CO2): M (CO2);
M (CO2) = 12 + 2 * 16 = 44 g / mol;
n (CO2) = 40: 44 = 0.9091 mol;
3. Determine the amount of calcium carbonate:
n (CaCO3) = n (CO2) = 0.9091 mol;
4. Let’s calculate the mass of carbonate:
m (CaCO3) = n (CaCO3) * M (CaCO3);
M (CaCO3) = 40 + 12 + 3 * 16 = 100 g / mol;
m (CaCO3) = 0.9091 * 100 = 90.91 g;
5. Find the mass fraction of calcium carbonate in limestone:
w (CaCO3) = m (CaCO3): m (limestone) = 90.91: 100 = 0.9091 or 90.91%.
Answer: 90.91%.