# I would really aprreciate if someone could help me, thank you so much.

The white limestone cliffs of Dover, England, contain a large percentage of calcium carbonate(CaCO3). A sample of limestone weighing 84.4g reacts with an excess of hydrochloric acid to form calcium chloride.
CaCO3+2HCl (arrow) CaCl2+H2O+CO2
The mass of calcium chloride formes is 81.8g. What is the percentage of calcium carbonate in the limestone?

Appreciate all the help.

Make sure the equation is balanced.
81.8 g CaCl2 = ?? mols CaCl2.
??mols CaCl2 = mols CaCO3 (from the equation).
mols CaCO3 = ?? grams CaCO3.
%CaCO3 = (g CaCO3/84.4) x 100 = ??
Post your work if you get stuck.

## To find the percentage of calcium carbonate in the limestone, we need to follow a series of steps:

1. Start by balancing the equation: CaCO3 + 2HCl ⟶ CaCl2 + H2O + CO2. The equation is already balanced.

2. Calculate the number of moles of calcium chloride formed. We are given the mass of calcium chloride, which is 81.8g. To find the number of moles, we need to use the molar mass of calcium chloride (CaCl2), which is 40.08g/mol + (2 * 35.45g/mol) = 110.98g/mol.

Moles of CaCl2 = Mass of CaCl2 / Molar mass of CaCl2
= 81.8g / 110.98g/mol
= 0.737 mol CaCl2

3. According to the balanced equation, the ratio between calcium chloride (CaCl2) and calcium carbonate (CaCO3) is 1:1. Therefore, the number of moles of calcium carbonate is also 0.737 mol.

4. Next, we need to find the mass of calcium carbonate (CaCO3) in grams. To do this, we use the molar mass of calcium carbonate, which is 40.08g/mol + 12.01g/mol + (3 * 16.00g/mol) = 100.09g/mol.

Mass of CaCO3 = Moles of CaCO3 * Molar mass of CaCO3
= 0.737 mol * 100.09g/mol
= 73.65g CaCO3

5. Finally, we can calculate the percentage of calcium carbonate in the limestone using the formula:

% CaCO3 = (Mass of CaCO3 / Mass of limestone) * 100
= (73.65g / 84.4g) * 100
= 87.31%

Therefore, the percentage of calcium carbonate in the limestone is approximately 87.31%.