# How many iron atoms are present in a 16*g mass of FeCl_3?

Mar 25, 2017

We work out the molar quantity of iron in a $16 \cdot g$ mass of $\text{ferric chloride.....}$ and get approx. $6 \times {10}^{22}$ individual iron atoms.

#### Explanation:

$\text{Moles of}$ $F e C {l}_{3}$ $=$ $\text{Mass"/"Molar mass}$

$= \frac{16 \cdot g}{162.2 \cdot g \cdot m o {l}^{-} 1} = 0.099 \cdot m o l$

And so there $0.099 \cdot m o l$ of iron, and $3 \times 0.099 \cdot m o l$ of chlorine. How does that help us?

Well the mole is simply a number; one mole of stuff SPECIFIES precisely $6.022 \times {10}^{23}$ individual items of stuff.

And here our stuff was $F e C {l}_{3}$, and in each mole of this stuff there $3 \cdot m o l$ of chlorine atoms..........BUT one mole of iron.

$\text{And so number of iron atoms......}$

$= 0.099 \cdot m o l \times 6.022 \times {10}^{23} \cdot m o {l}^{-} 1 = 5.96 \times {10}^{22} \cdot \text{iron atoms.}$