Question

For each of the following mixtures, predict the range in which the boiling point will fall based on intermolecular forces.

a.) water (BP 100^oC) and hexane (BP 68^oC)

b.) acetone (BP 56^oC) and water

c.) octane (BP 125^oC) and diethyl ether (BP 35^oC)

d.) water and sodium acetate (MP 324^oC)

e.) octane and water

f.) methylene chloride (BP 40^oC) and water

g.) methylene chloride and caffeine (MP 235^oC)

Answer 1

a) Water and hexane are immicible. Hence on reaching 68^oC, hexane will start to boil from the mixture.
b) Acetone and water are soluble in each other due to favorable interactions. The boiling point will be close to acetone which has the lower boiling point among the two components.

c) The boiling point will be close to the boiling point of diethyl ether. The two will not have favorable interaction since one is polar and the other is nonpolar. Hence the solubility will be low. Thus near boiling temperature diethyl ether, the boiling will take place.

d) Due to presence of sodium acetate, there will be elevation of boiling point for water due to colligative property. Hence the boiling point will be slightly higher than 100^oC.

e) Octane and water are immiscible. Hence the boiling will take place at temperature close to the boiling point of octane.

f) Here there will be interactions between methylene chloride and water. But still the boiling should take place near the boiling temperature of methylene chloride since the interactions should not be very strong with water to alter the boiling point significantly.

g) Due to colligative property of caffeine, methylene chloride will boil at slightly higher temperature than 40^oC.