Question

30 g of urea (NH2CONH2) is dissolved in 171g of water.calculate the mole fraction of urea in the solution

Answer 1

Answer:

when 30 g of urea (NH2CONH2) is dissolved in 171g of water, the mole fraction of urea is 0.05.

Explanation:

Mass of urea given = 30$g$

The molar mass of urea = 60$g/mol$

mass of water given = 171$g$

the molar mass of water = 18$g/mol$

Mole fraction is the number of moles of the component divided by the total number of moles of all the components in the solution.

The formula can be written as= $x_{i}=\frac{n_{i}}{n_{\text {tot }}}$

Here number of moles of urea= $\frac{30}{60} = 0.5 moles$

Number of moles of water = $\frac{171}{18} = 9.5 moles$

The total number of moles = 9.5+0.5 = 10 moles

Therefore mole fraction of urea = $x_{i}=\frac{n_{i}}{n_{\text {tot }}} = \frac{0.5}{10}$=0.05