Question

What is the mass in grams of 2.40 x1022 formula units of magnesium chloride? The molar mass of magnesium chloride is 95.211 grams/mole.

Answer 1

Solution:

Since, 6.023 x 10^23 formula units contains 1 mol of MgCl2

Hence, 2.40 x 10^22 formula units of MgCl2 contains,

= (2.40 x 10^22 ) (1 mol / 6.023 x10^23) = 0.03985 mol

Thus,

Mass of MgCl2 = Number of moles x Molar mass of MgCl2

= 0.03985 mol x 95.211 g mol-1

= 3.794 g = 3.80 g