Question

A solution containing 54 g of glucose (molecular mass = 180 g mol⁻¹) in 250 g of water (K_f for water = 1.86 K kg mol⁻¹).

What will be the molality of this glucose solution?

Options

• 1.20 m

• 0.12 m

• 2.40 m

• 0.24 m

Answer 1

1.20 m

Explanation:

Given: Mass of glucose = 54 g

Molar mass of glucose = 180 g/mol

Mass of water = 250 g = 0.250 kg

Moles of glucose = `54/180` = 0.3 mol

Molality (m) = `"Moles of solute"/"Mass of solvent in kg"`

= `0.3/0.250`

= 1.20 mol/kg