Q: A solution is prepared by dissolving 5.0 g of toluene ($$C_7H_8) in 225 g of $$benzene ($$C_6H_6). $$What is the mass percent of toluene in the solution?

$$\frac{5.0}{5.0 + 225} \times 100 = 2.2\%$$

Q: A solution is made by dissolving 50 g glucose ($$C_6H_{12}O_6$) in 500 g water. The vapor pressure of pure water at 25°C is 47.1 torr. What is the vapor pressure of the solution? (Assume mole fraction of water x$$_{H_2O} = 0.990$$)

$$P_{solution} = x_{H_2O} P_{H_2O} = 0.990 \times 47.1 = 46.6$$ torr

Q: A solution of ethylene glycol in water has a molality of 5.37 $$\mathrm{mol/kg}. If$$ $$K_b$$ for water is $$0.51\ ^\circ\mathrm{C}/\mathrm{m}$$ and $$i=1$$, what is the boiling point elevation?

$$\Delta T_b = iK_b m = 1 \times 0.51 \times 5.37 = 2.7\ ^\circ\mathrm{C}$$

Q: What is the osmotic pressure ($$\Pi) of a 0.031 M $$glucose solution at 25°C? ($$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$}$$, $$T = 298\ \mathrm{K}$$, $$i = 1)$$

$$\Pi = iMRT = 1 \times 0.031 \times 0.0821 \times 298 = 0.76\ \mathrm{atm}$$

Question 1

Which of the following best explains why mixing of gases is a spontaneous process?

Accepted Answer

It increases the entropy ($$S) of $$the system due to greater randomness in molecular positions.

Question 2

Which intermolecular force is primarily responsible for the solubility of NaCl in water?

Accepted Answer

Ion-dipole interactions

Question 3

A solution is prepared by dissolving 5.0 g of toluene ($$C_7H_8) in 225 g of $$benzene ($$C_6H_6). $$What is the mass percent of toluene in the solution?

Accepted Answer

$$\frac{5.0}{5.0 + 225} 	imes 100 = 2.2\%$$

Question 4

Which statement about molality ($$m) $$and molarity ($$M) is $$correct?

Accepted Answer

Molality does not change with temperature, while molarity does.

Question 5

A 0.155 M NaCl solution is isotonic with blood. What is the van't Hoff factor ($$i) $$for NaCl in water?

Accepted Answer

$$i = 2$$

Question 6

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more solute than is normally possible at a given temperature.

Question 7

Which equation correctly relates the concentration and volume before and after dilution?

Accepted Answer

$$C_1V_1 = C_2V_2$$

Question 8

Which of the following statements about colligative properties is true?

Accepted Answer

They depend only on the number of solute particles, not their identity.

Question 9

A solution is made by dissolving 50 g glucose ($$C_6H_{12}O_6$) in 500 g water. The vapor pressure of pure water at 25°C is 47.1 torr. What is the vapor pressure of the solution? (Assume mole fraction of water x$$_{H_2O} = 0.990$$)

Accepted Answer

$$P_{solution} = x_{H_2O} P_{H_2O} = 0.990 	imes 47.1 = 46.6$$ torr

Question 10

Which of the following will increase the boiling point of water the most?

Accepted Answer

Adding NaCl, a strong electrolyte

Question 11

Which formula is used to calculate the freezing-point depression of a solution?

Accepted Answer

$$\Delta T_f = -iK_f m$$

Question 12

A solution of ethylene glycol in water has a molality of 5.37 $$\mathrm{mol/kg}. If$$ $$K_b$$ for water is $$0.51\ ^\circ\mathrm{C}/\mathrm{m}$$ and $$i=1$$, what is the boiling point elevation?

Accepted Answer

$$\Delta T_b = iK_b m = 1 	imes 0.51 	imes 5.37 = 2.7\ ^\circ\mathrm{C}$$

Question 13

Which of the following best describes osmosis?

Accepted Answer

The net movement of solvent molecules from a region of low solute concentration to high solute concentration across a semipermeable membrane.

Question 14

What is the osmotic pressure ($$\Pi) of a 0.031 M $$glucose solution at 25°C? ($$R = 0.0821\ \mathrm{L\cdot atm\cdot $$mol^{-1}$$\cdot K$$^{-1}$$}$$, $$T = 298\ \mathrm{K}$$, $$i = 1)$$

Accepted Answer

$$\Pi = iMRT = 1 	imes 0.031 	imes 0.0821 	imes 298 = 0.76\ \mathrm{atm}$$

Question 15

Which of the following is a characteristic of colloids?

Accepted Answer

They scatter light due to the Tyndall effect.

Question 16

Which type of vitamin is stored in fatty tissue and why?

Accepted Answer

Fat-soluble vitamins, because they are nonpolar and dissolve in nonpolar environments.

Question 17

Which of the following best describes the effect of pressure on the solubility of gases in liquids?

Accepted Answer

Increasing pressure increases the solubility of gases in liquids, as described by Henry's Law.

Question 18

Which equation represents Henry's Law for the solubility of a gas?

Accepted Answer

$$S_g = kP_g$$

Properties of Solutions – General Chemistry Study Notes (Chapter 13)

Guida di studio - Domande di pratica

Study guide - Flashcard