Question

A solution containing urea (molecular mass =\[60{\text{ }}gmo{l^{ - 1}}\]) is isotonic with a $5\%$ solution of a non-volatile solute. Calculate the molecular mass of this non-volatile solute.

Answer 1

Hint: The organic compound urea, also known as carbamide, has the chemical formula \[CO{(N{H_2})_2}.\]Two –\[N{H_2}\]groups are united by a carbonyl (-C=O) functional group in this amide.
Urea is the primary nitrogen-containing agent in mammalian urine and plays a vital function in the metabolism of nitrogen-containing compounds by animals. It's a colourless, odourless solid that's extremely water soluble and almost non-toxic.

Complete answer: When the effective osmole concentration of a solution matches that of another solution, it is said to be isotonic. Water will freely flow through the membrane without altering the concentration of solutes on either side in this state.
The term "nonvolatile" refers to a substance that has no potential to evaporate. There is less space for solvent molecules and some of the surface is now covered by solute particles. The vapour pressure of the solution is smaller than that of the pure solvent so the solute particles do not evaporate.
According to the equation, urea at is isotonic with a $5\%$ nonvolatile solute solution.
As a result, a molar concentration of $5\%$ nonvolatile solute\[ = \dfrac{{{\mathbf{50g}}/{\text{d}}{{\text{m}}^3}}}{{{\text{ Mol wt}}{\text{. of non volatile solute }}}} = \dfrac{{50}}{m}M\]
Since we know all solutions are isotonic to one another,
\[\dfrac{1}{6} = \dfrac{{50}}{m}\]
Hence, m = 50 x 6 = 300 g/mol

Note:
A solution is a homogeneous mixture made up of a solute that has been dissolved in a solvent. The dissolving medium is the solvent, and the solute is the material that is being dissolved. Many different kinds and forms of solutes and solvents may be used to provide solutions.