Give reasons for the following:
(a) Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.
(b) Aquatic animals are more comfortable in cold water than in warm water.
(c) Elevation of boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.
(a) Measurement of osmotic pressure method is preferred for the determination of molar masses of macromolecules such as proteins and polymers.
(b) Aquatic animals are more comfortable in cold water than in warm water.
(c) Elevation of boiling point of 1 M KCl solution is nearly double than that of 1 M sugar solution.
Solution
(a) Macromolecule solutions are very dilute: their and are too small to measure, but their osmotic pressure is still appreciable. Osmotic pressure is also measured at room temperature, so heat-sensitive proteins are not denatured.
(b) The solubility of a gas in water decreases with rise in temperature (dissolution of a gas is exothermic). Cold water therefore holds more dissolved oxygen, making it more comfortable for aquatic life.
(c) Boiling-point elevation is colligative. KCl dissociates into K + Cl () while sugar stays molecular, so 1 M KCl has about twice as many particles — and about double the elevation — of 1 M sugar.
(b) The solubility of a gas in water decreases with rise in temperature (dissolution of a gas is exothermic). Cold water therefore holds more dissolved oxygen, making it more comfortable for aquatic life.
(c) Boiling-point elevation is colligative. KCl dissociates into K + Cl () while sugar stays molecular, so 1 M KCl has about twice as many particles — and about double the elevation — of 1 M sugar.
CBSE Class 12 Board · 2016 · Subjective