Solutions · Question 47

AIPMT 2005MCQMedium📈 Topic in 0% papers+4−1

A solution has a 1 : 4 mole ratio of pentane to hexane. The vapour pressures of the pure hydrocarbons at 20 are 440 mm Hg for pentane and 120 mm Hg for hexane. The mole fraction of pentane in the vapour phase would be

0.200
0.549
0.786
0.478

Answer

(4) 0.478

Solution

In the liquid: xpentane = 15 = 0.2, xhexane = 0.8

ppentane = 440 0.2 = 88 mm Hg

phexane = 120 0.8 = 96 mm Hg

ptotal = 88 + 96 = 184 mm Hg

ypentane = ppentaneptotal = 88184 = 0.478

Answer: (4)

AIPMT 2005

Keep practising — Solutions

A solution of urea (mol. mass 60 g mol-1) boils at 100.18 at the atmospheric pressure. If Kf and Kb for water are 1.86 and 0.512 K kg mol-1 respectively, the above solution will freeze at

0.654
-0.654
6.54
-6.54

AIPMT 2005

Formation of solution from two components can be considered as (i) Pure solvent separated solvent molecules, H1 (ii) Pure solute separated solute molecules, H2 (iii) Separated solvent and solute molecules solution, H3 Solution so formed will be ideal if

Hsoln = H1 + H2 + H3
Hsoln = H1 + H2 - H3
Hsoln = H1 - H2 - H3
Hsoln = H3 - H1 - H2

AIPMT 2003

A solution containing components A and B follows Raoult's law when

A-B attraction force is greater than A-A and B-B
A-B attraction force is less than A-A and B-B
A-B attraction force remains same as A-A and B-B
volume of solution is different from sum of volumes of solute and solvent

AIPMT 2002

A solution contains non-volatile solute of molecular mass M2. Which of the following can be used to calculate the molecular mass of solute in terms of osmotic pressure?