Calculate the mass and number of HCI molecules reacted with 20 g of CACO3.

1. Let’s write down the reaction equation:

CaCO3 + 2HCl = CaCl2 + H2O + CO2;

2.Calculate the chemical amount of calcium carbonate:

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

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

n (CaCO3) = 20: 100 = 0.2 mol;

3. Determine the amount of hydrogen chloride and find its mass:

n (HCl) = n (CaCO3) * 2 = 0.2 * 2 = 0.4 mol;

m (HCl) = n (HCl) * M (HCl) = 0.4 * 36.5 = 14.6 g;

4.Calculate the number of HCl molecules:

N (HCl) = n (HCl) * Na = 0.4 * 6.02 * 10 ^ 23 = 2.408 * 10 ^ 23 molecules.

Answer: 14.6 g; 2.408 * 10 ^ 23 molecules.