Molality | MCQs

Explanation

The molality (m) of a solution is the moles of solute divided by the kilograms of solvent. A solution that contains 1.0mol of NaCl dissolved into 1.0kg of water is a "one-molal" solution of sodium chloride.

The symbol for molality is a lower-case m written in italics.

Explanation

The molar mass of ethylene glycol (C2H6O2) = 2(12.01) + 6(1.01) + 2(16.00) = 62.07 g/mol

Number of moles of ethylene glycol = 60 g / 62.07 g/mol ≈ 0.966 moles

Mass of water = 100 g - 60 g = 40 g

Now, we need to convert the mass of water to kilograms:

Mass of water = 40 g * (1 kg / 1000 g) = 0.04 kg

Now, we can calculate the molality:

Molality (m) = moles of solute / mass of solvent in kg

Molality = 0.966 moles / 0.04 kg ≈ 24.15 moles/kg.