How many formula units make up 12.8 g of magnesium chloride (mgcl2)? express the number of formula units numerically.

8.09 × 10²² formula units

Mass of MgCl₂ is 12.8 g

Required to calculate the formula units

1 mole of a compound contains the Avogadro's number formula units

That is;

1 mole = 6.022 × 10²³ formula units

The molar mass of MgCl₂ is 95.211 g/mol

Number of moles = Mass ÷ molar mass

Moles of MgCl₂ = 12.8 g ÷ 95.211 g/mol

                          = 0.1344 mole

1 mole =  6.022 × 10²³ formula units

Therefore;

Number of formula units = Moles × 6.022 × 10²³ formula units

                                    = 0.1344 mole × 6.022 × 10²³ formula units

                                     = 8.09 × 10²² formula units

Therefore, there are 8.09 × 10²² formula units in 12.8 g of MgCl₂

"the periodic table is arranged in order of atomic number."