Answer
There is a total of 0.263 mole in 25.0 g of $MgCl_2$
Work Step by Step
1. Determine the molar mass of this compound ($MgCl_2$), and setup the conversion factors:
Molar mass :
$Mg: 24.31g $
$Cl: 35.45g * 2= 70.90g $
24.31g + 70.90g = 95.21g
$ \frac{1 \space mole \space (MgCl_2)}{ 95.21 \space g \space (MgCl_2)}$ and $ \frac{ 95.21 \space g \space (MgCl_2)}{1 \space mole \space (MgCl_2)}$
2. Calculate the number of moles $(MgCl_2)$
$ 25.0g \times \frac{1 mole}{ 95.21g} = 0.263 mole$
