Question

How many formula units make up 36.0 g of magnesium chloride (MgCl2)?

Answer 1

Answer: There are $2.29\times 10^{23}$ formula units

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{36.0g}{95g/mol}=0.38moles$

1 mole of $MgCl_2$ contains = $6.023\times 10^{23}$ formula units

Thus 0.38 moles of $MgCl_2$ contains = $\frac{6.023\times 10^{23}}{1}\times 0.38=2.29\times 10^{23}$ formula units

Thus there are $2.29\times 10^{23}$ formula units