Osmotic Pressure

Q.1    Why a person suffering from high blood pressure is advised to take minimum quantity of common salt ?

Ans.    Osmotic pressure is directly proportional to the conc. of solutes. Our body fluid contain a number of solutes. On taking large amount of salts, ions enter the body fluid there by raising the conc. of the solutes. As a result osmotic pressure increases which may rapture the blood cells.

Q. 2     Chloro acetic acid is a monoprotic acid and has Ka = 1.36 × 10–3. Calculate b. p. of 0.01 M aqueous soln ? (Kb = 0.51 k kg/mol)

Ans.    Kb = 0.51 k kg/mol

            a  = Ka / C

                = 1.36 × 10–3 / 0.01

                = 0.3687

              i = 1 + a

                = 1 + 0.3687 = 1.3687

            DTb = i × Kb m

                 = 1.36 × 10–2 × .51

                 = 0.0069 °C

Q. 3   Which colligative property is preferred for the molar mass determination of macro molecules ? Why ?

Ans.    Osmotic pressure is preferred over all other colligative properties because :

            (a)    even in dil. soln the o. p.values are appreciably high and can be measured accurately.

            (b)       o. p.can be measured at room temp. on the other hand elevation in B. P. is measured at high temp. where the solute may decompose. The depression in freezing point is measured at low temp.