Question

The recommended daily allowance (rda of calcium is 1.2 g. calcium carbonate contains 12.0% calcium by mass. how many grams of calcium carbonate are needed to provide the rda of calcium?

Answer 1

Answer:

10 grams of calcium carbonate are needed to provide the recommended daily allowance of calcium.

Explanation:

The recommended daily allowance (rda) of calcium = 1.2 g

Percentage of calcium by mass in calcium carbonate = 12.0%

Total mass of calcium carbonate be x

$\%=\frac{\text{Mass of an element}}{\text{Total mass of compound}}\times 100$

$12.0\%=\frac{1.2 g}{x}\times 100$

x = 10 g

10 grams of calcium carbonate are needed to provide the rda of calcium.

Answer 2

1) Calcium carbonate contains 40.0% calcium by weight.
M(CaCO₃)=100.1 g/mol
M(Ca)=40.1 g/mol
w(Ca)=40.1/100.1=0.400 (40.0%)!

2) Mass fraction of this is excessive data.

3) The solution is:

m(Ca)=1.2 g

m(CaCO₃)=M(CaCO₃)*m(Ca)/M(Ca)

m(CaCO₃)=100.1g/mol*1.2g/40.1g/mol=3.0 g