Question 1

Which of the following statements best describes a colligative property?

Accepted Answer

It depends on the concentration of solute particles, not their identity.

Question 2

Which of the following is NOT a colligative property?

Accepted Answer

Density of the solvent

Question 3

A solution is prepared by dissolving 1 mole of NaCl in 1 kg of water. How many moles of particles are present in the solution, and why does this matter for colligative properties?

Accepted Answer

2 moles, because NaCl dissociates into Na\^+ and Cl\^- ions

Question 4

Which equation correctly represents the freezing point depression for a non-electrolyte solute?

Accepted Answer

$$\Delta T_f = K_f \cdot m$$

Question 5

Why does adding a non-volatile solute to water lower its vapor pressure?

Accepted Answer

The solute particles attract solvent molecules, reducing their tendency to escape into the vapor phase.

Question 6

Calculate the freezing point of a solution made by dissolving 195 g of sucrose ($$C_{12}H$$_{22}$$O_{11}$$, molar mass = 342 g/mol) in 200 g of water. ($$K_f$$ for water = 1.86 $$^\circ$C/m).

Accepted Answer

$$-5.301^\circC$$

Question 7

Which of the following solutions will have the highest boiling point elevation, assuming equal molal concentrations?

Accepted Answer

A solution of CaCl$$_2 ($$dissociates into 3 ions)

Question 8

Which formula is used to calculate the osmotic pressure ($$\pi) of a $$dilute solution?

Accepted Answer

$$\pi = MRT$$

Question 9

A red blood cell is placed in a 0.5% NaCl solution. What will happen to the cell and why?

Accepted Answer

It will swell and may burst because the solution is hypotonic.

Question 10

Which of the following best explains why salt is spread on icy roads in winter?

Accepted Answer

Salt lowers the freezing point of water, preventing ice formation.

Question 11

Given the following data: $$K_b$$ for water = 0.51 $$^\circC/m. $$What is the boiling point of a 3 m NaCl solution in water? (Assume complete dissociation.)

Accepted Answer

$$103.06^\circC$$

Question 12

Which of the following statements about electrolytes and colligative properties is correct?

Accepted Answer

Electrolytes increase colligative effects because they produce more particles in solution.

Question 13

Which equation correctly represents the boiling point elevation for an electrolyte solute?

Accepted Answer

$$\Delta T_b = K_b \cdot m \cdot n$$

Question 14

A solution contains 1 mole of MgCl$$_2$$ dissolved in 1 kg of water. How many moles of particles are present, and how does this affect the freezing point depression?

Accepted Answer

3 moles; the effect is tripled compared to a non-electrolyte

Question 15

Which of the following best describes an isotonic solution with respect to red blood cells?

Accepted Answer

A solution with the same osmotic pressure as blood, causing no net movement of water.

Question 16

Which of the following is the correct expression for the vapor pressure of a solvent in a solution containing a non-volatile solute, according to Raoult's Law?

Accepted Answer

$$P_{solution} = P^0$_{solvent} X_{solvent}$$

Question 17

A 1 g sample of sucrose (molar mass = 342 g/mol) is dissolved in 100 mL of solution at 25$$^\circC. $$What is the osmotic pressure in mm Hg? ($$R = 62.4 L mm Hg / K $$mol)

Accepted Answer

$$543.72 mm Hg$$

Question 18

Which of the following best explains why the boiling point of a solution is higher than that of the pure solvent?

Accepted Answer

More heat is required to raise the vapor pressure of the solution to atmospheric pressure.

Question 19

Which of the following will have the greatest effect on lowering the freezing point of water: 1 molal NaCl, 1 molal CaCl$$_2$$, or 1 molal glucose? (Assume complete dissociation.)

Accepted Answer

1 molal CaCl$$_2$$

Colligative Properties: Principles and Applications

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