Question

A `2.03*g` mass of calcium salts contains `1.33*g` calcium carbonate. What is the `%` calcium carbonate; and what is the percentage by mass of of calcium in calcium carbonate?

Answer 1

`"%calcium carbonate (by mass)"=(1.33*g)/(2.03*g)xx100%=65.5%`

`"%calcium (by mass)"=26.2%`

Explanation:

So we have the `"%calcium carbonate, "m/m`. We are not finished yet, because we have to address the percentage by mass of calcium metal in calcium carbonate:

`%Ca=(40.08*g*mol^-1)/(100.09*g*mol^-1)=40%` with respect to calcium carbonate.

And thus the `%Ca` IN THE SAMPLE

`=(1.33*g)/(2.03*g)xx(40.08*g*mol^-1)/(100.09*g*mol^-1)xx100%=26.2%`

We have assumed that ALL of the calcium metal is present as the carbonate.