Discussion Forum



1)

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 $kg^{-1}$

Answer:

Option A

Explanation:

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$