Question

6g urea is dissolved in 90g water.the mole fraction of solute is

Answer 1

Answer:

weight of urea /molecular weight=6/60=0.1molecule.

moles of H2O=weight of water/molecular weight=90/18=5

mole fraction of urea =0.1/0.1+5

=0.1/5.1

=1/51

Answer 2

Answer:

The mole fraction of the solute ( urea ) is $\frac{1}{51}$.

Explanation:

Given,

The mass of the urea ( solute ) = $6g$

The solvent's mass (water) = $90g$

The mole fraction of urea ( solute ) =?

As we know,

• The mole fraction of solute can be calculated by the formula given below:
• The mole fraction of solute = $\frac{n_{solute} }{n_{solute} + n_{solvent}}$    -------equation (1)

Here,

• $n_{solute}$ = number of moles of solute
• $n_{solvent}$ = number of moles of solvent

As we know,

• The molar mass of urea = $60g/mol$
• The molar mass of water = $18g/mol$

Now,

• The solute's number of moles (urea) = $\frac{Given mass }{Molar mass}$ = $\frac{6}{60}$ = $0.1 mol$
• The solvent's number of moles (water) = $\frac{Given mass }{Molar mass}$ = $\frac{90}{18}$ = $5 mol$

After putting the calculated values in equation (1), we get:

• The solute's mole fraction = $\frac{0.1}{0.1+5}$ = $\frac{0.1}{5.1}$ = $\frac{1}{51}$.