Q: A solution is prepared by dissolving 2.0 mol of NaCl in 1.0 kg of water. What is the molality ($$m) of $$the solution?

$$m = \frac{2.0\ \text{mol}}{1.0\ \text{kg}} = 2.0\ \text{m}$$

Q: Which equation correctly expresses molarity ($$M$$)?

$$M = \frac{\text{mass of solute in mol}}{\text{volume of solution in L}}$$

Q: Given a solution with a mole fraction of solvent $$X_{\text{solvent}} = 0.8$$ and a pure solvent vapor pressure $$P^\circ_{\text{solvent}} = 100\ \text{torr}$$, what is the vapor pressure of the solution ($$P_{\text{soln}}) $$according to Raoult’s Law?

$$P_{\text{soln}} = 0.8 \times 100 = 80\ \text{torr}$$

Q: A solution is prepared by dissolving 10 g of NaCl in 990 g of water. What is the approximate parts per thousand (ppt) of NaCl in the solution?

$$\text{ppt} = \frac{10}{1000} \times 1000 = 10$$

Q: A solution contains 0.5 mol of solute and 9.5 mol of solvent. What is the mole fraction of the solute ($$x_{\text{solute}}$$)?

$$x_{\text{solute}} = \frac{0.5}{0.5 + 9.5} = 0.05$$

Question 1

Which of the following statements best describes a colligative property?

Accepted Answer

A property that depends on the quantity of particles, but not their chemical nature.

Question 2

A solution is prepared by dissolving 2.0 mol of NaCl in 1.0 kg of water. What is the molality ($$m) of $$the solution?

Accepted Answer

$$m = \frac{2.0\ 	ext{mol}}{1.0\ 	ext{kg}} = 2.0\ 	ext{m}$$

Question 3

Which equation correctly expresses molarity ($$M$$)?

Accepted Answer

$$M = \frac{	ext{mass of solute in mol}}{	ext{volume of solution in L}}$$

Question 4

Why must the solute be added before filling the volumetric flask to the mark when preparing a solution of known molarity?

Accepted Answer

To ensure the final volume is accurate and includes the solute.

Question 5

Which of the following is temperature-independent when measuring concentration?

Accepted Answer

Molality

Question 6

Raoult’s Law is used to calculate which property of a solution?

Accepted Answer

Vapor pressure lowering

Question 7

Given a solution with a mole fraction of solvent $$X_{	ext{solvent}} = 0.8$$ and a pure solvent vapor pressure $$P^\circ_{	ext{solvent}} = 100\ 	ext{torr}$$, what is the vapor pressure of the solution ($$P_{	ext{soln}}) $$according to Raoult’s Law?

Accepted Answer

$$P_{	ext{soln}} = 0.8 	imes 100 = 80\ 	ext{torr}$$

Question 8

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

Accepted Answer

The solute lowers the vapor pressure, requiring a higher temperature to boil.

Question 9

A 1.0 m solution of glucose (a non-electrolyte) is compared to a 1.0 m solution of NaCl (an electrolyte). Which will have the greater freezing point depression?

Accepted Answer

The NaCl solution, because it produces more particles in solution.

Question 10

Which formula correctly expresses osmotic pressure ($$\Pi) $$for a dilute solution?

Accepted Answer

$$\Pi = MRT$$

Question 11

What is the van’t Hoff factor ($$i) $$for a solution of NaCl, assuming complete dissociation?

Accepted Answer

$$i = 2$$

Question 12

Which of the following is NOT a colligative property?

Accepted Answer

Color change of the solution

Question 13

A solution is prepared by dissolving 10 g of NaCl in 990 g of water. What is the approximate parts per thousand (ppt) of NaCl in the solution?

Accepted Answer

$$	ext{ppt} = \frac{10}{1000} 	imes 1000 = 10$$

Question 14

Which of the following best describes an ideal solution?

Accepted Answer

A solution that follows Raoult’s Law at all concentrations.

Question 15

Which phenomenon is observed when a beam of light passes through a colloidal dispersion?

Accepted Answer

Tyndall effect

Question 16

A solution contains 0.5 mol of solute and 9.5 mol of solvent. What is the mole fraction of the solute ($$x_{	ext{solute}}$$)?

Accepted Answer

$$x_{	ext{solute}} = \frac{0.5}{0.5 + 9.5} = 0.05$$

Question 17

Which of the following best explains why molality is preferred over molarity for colligative property calculations?

Accepted Answer

Molality is independent of temperature because it is based on mass, not volume.

Question 18

Which of the following is true about osmotic pressure in biological systems?

Accepted Answer

Osmotic pressure causes water to move from a region of low solute concentration to high solute concentration.

Solutions and Colligative Properties (General Chemistry Chapter 14, Part 2)

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