# How many moles of ions are in 27.5 g of MgCl_2?

$M g C {l}_{2} \left(s\right) \rightarrow M {g}^{2 +} + 2 C {l}^{-}$
$\text{Moles of magnesium salt}$ $=$ $\frac{27.5 \cdot g}{95.21 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.289 \cdot m o l .$
There are thus $2 \times 0.289 \cdot m o l$ $\text{chloride ions}$, and $0.289 \cdot m o l$ $\text{magnesium ions}$, almost an entire mole of ions.