Question

Read the passage given below and answer the questions that follow.

When two solutions are separated by a semi-permeable membrane, the solvent molecules move from a solution of lower molar concentration to a solution of higher molar concentration through osmosis.

1. Samar removed the outer hard shell of two different eggs while cooking at home. He then placed one egg in pure water and the other egg in a saturated solution of sucrose. What change is he likely to observe in the eggs after a few hours?
2. Which solution, hypertonic or hypotonic, has a higher amount of solute in same quantity of solution?
3. A 5% aqueous solution of glucose (molar mass = 180 g mol^-1) is isotonic with 1.66 % aqueous solution of urea. Calculate the molar mass of urea.

Answer 1

1. The low concentration of solvent (water) in the egg allows it to swell after a few hours, whereas the low concentration of solvent (water) in the solution causes the other egg, which is placed in a saturated solution of sucrose, to shrink.
2. A hypertonic solution has a higher amount of solute in the same quantity of solution.

3. For isotonic solution, π₁ = π₂

   `π_"Glucose" = "C"_1"RT"`

   `π_"Uurea" = "C"_2"RT"`

   For isotonic solution,

   `π_"Glucose" = π_"turea"`

   C₁RT = C₂RT

   C₁ = C₂

   `therefore ("W"_1)/("M"_1) = ("W"_2)/("M"_2)`

   `therefore (5 × 1000)/(180 × 100) = (1.66 × 1000)/("M" × 100)`

   M = 59.76 g mol^-1

   Thus, the molar mass of urea will be 59.76 g mol^-1.