Calculate the molarity of each of the following solutions: (a) 30 g of Co(NO₃)₂. 6H₂O in 4.3 L of solution (b) 30 mL of 0.5 M H₂SO₄ diluted to500 mL.

Molarity is the concentration of a solution expressed as the number of moles of solute per litre of solution.

Molarity =

(a) Given,

In 4.3 L of solution there is 30 g of Co(NO₃)₂. 6H₂O

Molar mass of Co(NO₃)₂.6H₂O = (1 × 59 + 2 × (1 × 14 + 3 × 16) + 6 × 18)

= 291 g/mol.

∴ Moles = = 0.103 mol.

Now, Molarity =

= 0.023 M

(b) Given,

30 mL of 0.5 M H₂SO₄ diluted to500 mL.

In 1000 mL of 0.5 M H₂SO₄, number of moles present is 0.5 mol.

∴ In 30 mL of 0.5 M H₂SO₄, number of moles present = mol.

= 0.015 mol.

∴ Molarity =

= 0.03 M.