Question

1. If an aqueous solution that is 0.15 M in HF has an osmotic pressure of 3.9 atm at 25oC, what is the percent ionization of HF at this concentration?

2. A mixture of 2 volatile liquids is said to be ideal if each component obeys Raoult’s Law:

Pi=XiPio

Two volatile liquids A (molar mass 100 g/mol) and B (molar mass 110 g/mol) form an ideal solution. At 55oC, A has a vapor pressure of 98 mm Hg and B has a vapor pressure of 42 mmHg. A solution is prepared by mixing equal masses of A and B.


Calculate the mole fraction of each component in the solution.

Answer 1

pi = iMRT
Solve for i (use 0.08206 for R).

Then effective M = i*0.15 = ?
Then HF ==> H^+ + F^-
(H^+)=(F^-) = x
(HF = 0.15-x
Then x+x+0.15-x = i*0.15
Solve for x = (H^+) and
%ion = (H^+)/0.15)*100 =

Answer 2

What's the problem with #2? Just take equal amount of A and B (it doesn't mattr how many g you take as long as the amounts are equal). Calculate X of each and from there solve for p of each. I can help you if you get stuck.