Question

If one mole friction of urea in its aqueous solution is 0.1 then the molality of the solution will be?

Answer 1

THE CORRECT QUESTION:

Mole fraction of urea in its aqueous solution is 0.02 then its morality will be..

Answer:

GIVEN :- mole fraction of urea in the given aqueous solution is 0.02.

MOLE FRACTION OF WATER WILL BE :-

= 1 - mole fraction of urea

= 1 - 0.02

= 0.98

Thus, no. of moles of urea in the solution will be = mole fraction of urea in solution X total number of moles of the solution 

= 0.02 X 1 = 0.02

Similarly, the number of moles of water in the solution will be = mole fraction of water in solution X total number of moles of the solution 

= 0.98 X 1

= 0.98

So, mass of urea present in solution will be = number of moles of urea X molar mass of urea

= 0.02 X 60

= 1.2g

Similarly mass of water present in the solution will be = number of moles of water X molar mass of water

= 0.98 X 18 = 17.64g

Now, molality of a solution is given by the following relation

molality = number of moles of solute / Mass of solvent (in Kg)

So, molality of urea solution will be = 0.02 / 0.0176

= 1.136 m