# Question bb58b

May 22, 2016

$1.32 \setminus \times {10}^{22} \text{ formula units of CaO}$. Note that "CaO"-does not form discrete molecules so we talk in terms of formula units. Unfortunately the question itself misleads by using "molecules".

#### Explanation:

First you need the molar mass. $\text{CaO}$ has one atom of $\text{Ca (atomic mass 40.08)}$ and one atom of $\text{O (atomic mass 16.00)}$. So we add the two atoms:

$40.08 + 16.00 = 56.08 \text{ g/mol}$

Now divide the mass by the molar mass and multiply by Avogrado's Number:

{1.23" g"}/{{56.08" g"}/"mol"}\times{6.022\times10^{23}" formula units"}/"mol"
$= 1.32 \setminus \times {10}^{22} \text{ formula units}$