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

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.