# How many moles are there in 4.75g of magnesium chloride?

There are $\text{0.0499 mol MgCl}$ in $\text{4.75 g}$.
The molar mass (mass of one mole) of magnesium chloride, $\text{MgCl"_2}$, is $\text{95.211 g/mol}$. To calculate the number of moles of $\text{MgCl"_2}$ in $\text{4.75 g}$, divide the given mass by the molar mass.
$4.75 \cancel{\text{g MgCl"_2xx(1"mol MgCl"_2)/(95.211cancel"g MgCl"_2)="0.0499 mol MgCl"_2}}$ (rounded to three significant figures)