Answer:
0.0975 mol of solute (urea).
Explanation:
Let's remember the formula of molality:
[tex]Molality\text{ \lparen m\rparen=}\frac{moles\text{ of solute}}{kilograms\text{ of solvent}}=\frac{mol}{kg}.[/tex]As we have the mass of the solvent (water) in g but not in kg, we have to convert it. Remember that 1 kg equals 1000 g:
[tex]500.0\text{ g }\cdot\frac{1\text{ kg}}{1000\text{ g}}=0.5\text{ kg.}[/tex]Now, let's solve for 'moles of solute' and replace the data that we have, like this:
[tex]\begin{gathered} moles\text{ of solute=molality}\cdot kilograms\text{ of solvent,} \\ moles\text{ of solute=1.95}\cdot10^{-1}\text{ m}\cdot0.5\text{ kg,} \\ moles\text{ of solute=0.0975 moles.} \end{gathered}[/tex]The answer would be that we have 0.0975 mol of solute (urea) in the solution.
