# What percent of calcium carbonate is oxygen?

Jan 22, 2017

Oxygen makes up 48% of the mass of $C a C {O}_{3}$

#### Explanation:

To calculate percent composition by mass, you start by considering one mole of the given compound. The mass of one mole of calcium carbonate is 100.1 g

Of that mass,

40.1 g is due to the one mole of calcium atoms it contains.

12.0 g is due to the one mole of carbon in it, and

48.0 g is due to the three moles of oxygen atoms in one mole of $C a C {O}_{3}$

Now. to find percent composition, you take each element separately, and do this calculation:

$\left(\text{mass of element" )/("molar mass of compound}\right) \times 100$

So, for oxygen, this would be

(48.0)/(100.1) xx100=48.0%