a) What is meant by:
i) Colligative properties
ii) Molality of a solution
b) What concentration of nitrogen should be present in a glass of water at room temperature? Assume a temperature of 25°C, a total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0.78. (K for nitrogen = 8.42 × 10 M/mm Hg)
i) Colligative properties
ii) Molality of a solution
b) What concentration of nitrogen should be present in a glass of water at room temperature? Assume a temperature of 25°C, a total pressure of 1 atmosphere and mole fraction of nitrogen in air of 0.78. (K for nitrogen = 8.42 × 10 M/mm Hg)
Solution
(a)(i) Colligative properties are properties of dilute solutions that depend only on the number of solute particles present, not on their nature — relative lowering of vapour pressure, elevation of boiling point, depression of freezing point and osmotic pressure.
(ii) Molality is the number of moles of solute dissolved per kilogram of the solvent.
(b) Partial pressure of nitrogen:
With given in M per mm Hg, Henry's law reads :
(ii) Molality is the number of moles of solute dissolved per kilogram of the solvent.
(b) Partial pressure of nitrogen:
With given in M per mm Hg, Henry's law reads :
CBSE Class 12 Board · 2009 · All India · Subjective