a) When 2.56 g of sulphur was dissolved in 100 g of CS, the freezing point lowered by 0.383 K. Calculate the formula of sulphur (S). (K for CS = 3.83 K kg mol, atomic mass of sulphur = 32 g mol)
b) Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing
i) 1.2% sodium chloride solution
ii) 0.4% sodium chloride solution?
b) Blood cells are isotonic with 0.9% sodium chloride solution. What happens if we place blood cells in a solution containing
i) 1.2% sodium chloride solution
ii) 0.4% sodium chloride solution?
Solution
(a) Molality:
Moles of S in 100 g CS = mol.
Molar mass:
Atoms per molecule:
(b)(i) In 1.2% NaCl (hypertonic), the outside solution has the higher osmotic pressure: water moves out of the cells (exosmosis) and they shrink (crenation).
(ii) In 0.4% NaCl (hypotonic), water moves into the cells (endosmosis): they swell and may finally burst (haemolysis).
Moles of S in 100 g CS = mol.
Molar mass:
Atoms per molecule:
(b)(i) In 1.2% NaCl (hypertonic), the outside solution has the higher osmotic pressure: water moves out of the cells (exosmosis) and they shrink (crenation).
(ii) In 0.4% NaCl (hypotonic), water moves into the cells (endosmosis): they swell and may finally burst (haemolysis).
CBSE Class 12 Board · 2016 · Delhi · Subjective