Question

Calculate the moles of aqueous calcium carbonate present in a 50.00mL sample of a calcium carbonate standard solution, assuming the standard is known to have a hardness of 125 ppm (hardness due to CaCO3). You can assume that the density of the sample is 1.000 g/mL and the molar mass of calcium carbonate is 100.0 g/mol.

Answer 1

1 ppm = 1 mg/L.
So 125 ppm = 125 mg/L.
You will have 125 mg/L x 0.050 L = 6.25 mg or 0.00625 g.
Then mols = grams/molar mass = ?

Answer 2

.0000625