HONORS CHEMISTRY

HOMEWORK 8f. Name: _________________________________________

SOME USEFUL FREEZING POINT AND BOILING POINT CONSTANTS:

K_b = 0.51^oC/molal = 0.51 kg K /mol for water at 100^oC

K_f = -1.86^oC/molal = -1.86 kg K /mol for water at 0^oC

K_f = -39.7^oC/molal = -39.7 kg K /mol for camphor at 178.8^oC

1. Glycerine (C₃H₈O₃) is a nonelectrolyte. How many grams of glycerine must be dissolved in 200.0 g of water to make a solution whose freezing point is -1.50^o C?

2. Ethylene glycol (C₂H₆O₂) is a nonelectrolyte. Find the freezing point and boiling point of an antifreeze solution that is 50.0% C₂H₆O₂ by mass.

3. Calculate the freezing point and boiling point of each of the following, assuming complete dissociation:

a.) 0.050 molal MgCl₂ in water b.) 0.050 molal FeCl₃ in water