Molality and Colligative Properties

The freezing point of a solution is ___________ that of a pure solvent

• more than

• less than

• equal to

The boiling point of a solution is ___________ that of a pure solvent

• more than

• less than

• equal to

Solution A contains 0.1 mol of sucrose, dissolved in 500. g of water. Solution B contains 0.1 mol of sodium chloride, dissolved in 500. g of water. Which fo the following statements about theses solutions is true?

• Both solutions have the same vapor pressure.

• Solution A would boil at a higher temperature than solution B would.

• Solution A would freeze at a higher temperature than solution B would.

• Both solutions would boil at the same temperature.

molality is

• the moles of solute in 1g of solvent

• the moles of solute in 1g of solution

• the moles of solute in 1kg of solvent

• the moles of solute in 1kg of solution

Calculate the approximate boiling point (in ^oC) of a solution of 285 g of magnesium chloride in 2.0 kg of water. (K_b=0.51 ^oC/m)

• 103.1 ^oC

• 101.6 ^oC

• 102.3 ^oC

• 104.8 ^oC

If 4.27 g sucrose (C12H22O11) are dissolved in 15.2 g water, what is the boiling point of the resulting solution? Kb for water = 0.512°C/m. ΔTb = i x Kb x m.

• 100.42 ^oC

• 10.42 ^oC

• 100 ^oC

• 42 ^oC

• None of them

Colligative properties are dependent only on the number of particles in a solution, and not their identity.

• True

• False

What is the boiling point of a solution created when four moles of glucose are dissolved in two kilograms of water?

Assume that glucose is a nonvolatile solute.

kb water

=0.515∘C.kg/mol

• 101.03 ^∘C

• 10.1 ^∘C

• 0.101 ^∘C

• 10103 ^∘C

• None of them

What is the van't Hoff factor for the compound Na₂SO₄

• 1
• 3
• 5
• 7

What is the van't Hoff factor for the compound CH₃OH?

• 1
• 3
• 6
• 9