If 0.2 mol of the following substances are required how many grams of those substances should be taken?

Sodium chloride, magnesium oxide,calcium carbonate

(a) Sodium Chloride

Moles = Mass of subtance in grams /Molecular Mass(in g/mol)

Molecular mass of NaCl = 1× (Atomic mass of Na) + 1× (Atomics mass of Cl)

= 1× (23) + 1× (35.5)

= 55.5

Mole = 0.2 mol(given)

0.2 = given mass/55.5

Given mass = 0.2× 55.5

= 11.1g

(b) Magnesium Oxide

Moles = Mass of subtance in grams /Molecular Mass(in g/mol)

Molecular mass of MgO = 1× (Atomic mass of Mg) + 1× (Atomics mass of O)

= 1× (24) + 1× (16)

= 40

Mole = 0.2 mol(given)

0.2 = given mass/40

Given mass = 0.2× 40

= 8g

(c) Calcium Carbonate

Moles = Mass of subtance in grams /Molecular Mass(in g/mol)

Molecular mass of CaCO₃ = 1× (Atomic mass of Ca) + 1× (Atomics mass of C) + 3× (atomic mass of O)

= 1× (40) + 1× (12) + 3× (16)

= 100

Mole = 0.2 mol(given)

0.2 = given mass/100

Given mass = 0.2× 100

= 20g