How many milligrams of calcium is in 1.61-g of calcium carbonate?

Answer 1

Hi Joy,

For this question, you want to find the percent mass of calcium and carbonate. Here are the steps you want to follow. The answer is below the steps, but I encourage you to try this on your own first:

1. Write down the formula for calcium carbonate.
2. Use the periodic table to find the mass of 1mol of each element separately.
3. Use the equation to find the percent mass of calcium: Percent Mass = Mass_Ca/Mass_CaCO3
4. Multiply the percent mass by the total mass of calcium carbonate to find your answer.

Note: If you are familiar with dimensional analysis, you may combine the third and fourth step into one.

ANSWER:

1. CaCO₃
2. Ca: 40.1 g/mol(grams per mole), C: 12.0 g/mol, O: 16.0 g/mol
3. Percent Mass = Mass_Ca/(Mass_CaCO3) = 40.1/(40.1 + 12.0 + 3*16.0) = 40.1/100.1 = 0.401 = 40.1%
4. Mass_Ca = Percent Mass * Mass_Total = 40.1% * 1.61 g = 0.646g