<h3>
Answer:</h3>
8.09 × 10²² formula units
<h3>
Explanation:</h3>
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
<h3>
Step 1: Calculate the moles of MgCl₂ in 12.8 g </h3>
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
<h3>Step 2: Calculate the formula units of MgCl₂</h3>
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
