# How many moles are in "1.68 g Fe"?

Jul 25, 2017

There is $\text{0.0301 mol Fe}$ in $\text{1.68 g Fe}$.

There are $1.81 \times {10}^{22}$ atoms in $\text{1.68 g Fe}$.

#### Explanation:

Divide the mass of iron by its molar mass in g/mol to get the moles of iron.

(1.68color(red)cancel(color(black)("g Fe")))/(55.845color(red)cancel(color(black)("g Fe"))/"mol Fe")="0.0301 mol Fe"

One mole of anything is $6.022 \times {10}^{23}$ of anything, including atoms. Multiply mol Fe by $\frac{6.022 \times {10}^{23}}{\text{mol}}$.

0.0301color(red)cancel(color(black)("mol Fe"))xx(6.022xx10^23"atoms Fe")/(1color(red)cancel(color(black)("mol Fe")))=1.81xx10^22 "atoms Fe" (rounded to three sig figs)