Question

An aqueous solution of NaCl is prepared by dissolving pure NaCl in pure water and the solution was found to contain
12% NaCl by weight. Determine the molality of this solution.​

Answer 1

Hey Dear,

◆ Answer -

Molality = 2.35 m

◆ Explaination -

Let's consider 100 g of solution.

Mass of NaCl will be -

W2 = 100 × 12/100

W2 = 12 g

No of moles of NaCl is -

n2 = W2 / M2

n2 = 12/58 mol

Mass of water in solution is -

W1 = 100 - 12

W1 = 88 g

W1 = 88/1000 kg

Molality of the solution is calculated by formula -

Molality = moles of solute / mass of solvent

Molality = (12/58) / (88/1000)

Molality = 2.35 m

Therefore, molality of solution is 2.35 m.

Hope this helps you.