Chemistry | MHT CET 2017 | Discussion Page

The molality of solution containing 15.20 g of urea, (molar nass= 60) dissolved in 150g of water is

A) 1.689 mol

$kg^{-1}$

B) 0.1689 mol

$kg^{-1}$

C) 0.5922 mol

$kg^{-1}$

D) 10.2533 mol

$kg^{-1}$

Option A

Molality

(m) = Number of moles of solute / mass of solvent (in g) x 1000

= Mass of solute(in g)x 1000/ Molecular weight of solute

x mass of solvent (in g)

$=\frac{W_{solute} \times 1000}{M_{solute}\times W_{solvent}}$

$=\frac{15.2 \times 1000}{60\times 150}=1.689 mol/kg$

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