A 1.60 g calcium supplement contains 37.8% Ca by mass. The calcium is present in the supplement as CaCO3. How many grams of CaCO3 are in the calcium supplement?

Question

Molar mass: 100.09 g/mol

Answer 1

We are told the supplement is 1.6 g in total, and 37.8% of this supplement is calcium by weight. All calcium in the supplement is in the form of CaCO3 (molar mass=100.07 g).

1.6 (0.378) = 0.605 g of Ca

For every 1 mole of CaCO3 (molar mass of 100.07) there is 40.07 g of Ca.

If we use this proportion along with the amount in grams we know we have of calcium (0.605 g), we can determine the grams of CaCO3.

40.07/100.07 = 0.605/X

X=1.51 g of CaCO3