AP Chemistry
 Colligative Properties of Electrolytes Worksheet 

1. 
Why are
colligative properties of solutions of ionic compounds usually more pronounced
than those of solutions of the same molarities of molecular compounds? 
2. 
The vapor
pressure of water at 20^{o}C is 2.33 kPa. If the solute in
a solution made from 10.0 g of NaCl in 1.00 kg of water is 100% dissociated
(and is an ideal solution), what is the vapor pressure of this solution at
20^{o}C? 
3. 
Which
aqueous solution, if either, has the lower freezing point, 10% (w/w) NaCl
or 10% (w/w) NaI? 
4. 
Which
aqueous solution, if either, has the higher boiling point, 0.50 m NaI or 0.50 m Na_{2}CO_{3}? 
5. 
Which
aqueous solution, if either, has the higher osmotic pressure, 1.5% (w/w)
glucose (C_{6}H_{12}O_{6}, formula weight 180) or
1.5% (w/w) NaCl? 
6. 
What
is the van't off factor? What is its calculated value for all molecules
solutes? For all ionic solutes of the Na_{2}SO_{4}
type? 
7.

The van't
Hoff factor for the solute in 0.100 m
NiSO_{4} is 1.19. What would this factor be if the solution
behaved as if it were 100% dissociated? 
8. 
The van't
Hoff factor for the solute in 0.118 m
LiCl is 1.89. a) Calculate the freezing point of the solution. b) This solution is roughly as dilute as the solution in the question above. Explain why the van't Hoff factor for LiCl is so much greater. 
9. 
Consider
an aqueous 1.00 m of Na_{3}PO_{4}. a) Calculate the boiling point of this solution on the assumption that it does not ionize at all in solution. b) Do the same calculation assuming that it's van't Hoff factor reflects 100% dissociation into ions. c) The 1.00 m solution boils at 101.183^{o}C at 1 atm. Calculate the van't Hoff factor for this solute in this solution. 
10.

A 1.00
m aqueous solution
of HF freezes at 1.91^{o}C. According to these
data, what is the percent ionization of HF in this solution? 
11. 
An aqueous
solution of a weak electrolyte, HX, with a concentration of 0.125 m has a freezing point of 0.261^{o}C.
What is the percent ionization of this compound to two significant figures? 