Question

Explain what effect each of the following mistakes would have on a simple distillation: a) Failure to add a boiling stone. b) Heating the distillation flask too fast. c) Heating the distillation flask to dryness. d)Using a distillation flask that has a maximum capacity equal to the volume of liquid. e) Using a much larger (e.g., 50 mL) distillation flask. f)Putting the thermometer all the way into the liquid in the distillation flask 1. 2. Using Raoult's Law, calculate the vapor pressure of a solution containing 30 mol% hexane and 70 mol% octane at 90°C. The vapor pressure of the pure compounds at 90°C are as follows: 253 torr. hexane 1390 torr; octane

Answer 1

1. a. Otherwise solvent may bumped out.

b. Rate must be slower otherwise there will be less vapour condensation .

c. Solution may explode.

d. Solution may explode

e. Vapour cannot be transferred to the collecting flask.

f. To check if there is excess heating, which results in change in temperature