Question

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

Express the number of formula units numerically.

Answer 1

Answer: There are
`2.29* 10^(23)` formula units

Step-by-step explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number
`6.023* 10^(23)` of particles.

To calculate the moles, we use the equation:

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

1 mole of
`MgCl_2` contains =
`6.023* 10^(23)` formula units

Thus 0.38 moles of
`MgCl_2` contains =
`(6.023* 10^(23))/(1)* 0.38=2.29* 10^(23)` formula units

Thus there are
`2.29* 10^(23)` formula units