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 20oC 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 20oC?

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 Na2CO3?

5.
Which aqueous solution, if either, has the higher osmotic pressure, 1.5% (w/w) glucose (C6H12O6, 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 Na2SO4 type?

7.  
The van't Hoff factor for the solute in 0.100 m  NiSO4 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 Na3PO4.
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 101.183oC 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 -1.91oC.    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 -0.261oC.  What is the percent ionization of this compound to two significant figures?