# How many gold atoms are contained in 0.650 grams of gold?

Dec 8, 2015

$\text{0.650 g Au}$ contain $1.99 \times {10}^{21} \text{atoms}$.

#### Explanation:

Calculate the moles of gold by dividing the given mass by its molar mass, $\text{196.966569 g/mol}$ (atomic weight on periodic table in g/mol).

(0.650cancel"g Au")/(196.966569 cancel"g"/"mol" "Au")="0.00330 mol Au atoms"

$1 \text{mol atoms"=6.022xx10^23 "atoms}$

Multiply the calculated mol Au times $\left(6.022 \times {10}^{23} \text{atoms")/(1"mol}\right)$.

$0.00330 \cancel{\text{mol Au"xx(6.022xx10^23"atoms")/(1cancel"mol")=1.99xx10^21 "atoms Au}}$