Q: Which of the following statements about the enthalpy of solution ($$\Delta H_{\text{sol}}) is $$correct?

$$\Delta H_{\text{sol}} is $$the sum of the enthalpy changes for breaking solute-solute, solvent-solvent, and forming solute-solvent interactions.

Q: According to Henry's Law, which equation correctly relates the solubility of a gas ($$S_{\text{gas}}) to $$its partial pressure ($$P_{\text{gas}}) $$above a solution?

$$S_{\text{gas}} = k_H \cdot P_{\text{gas}}$$

Q: A solution is prepared by mixing 3.95 g of carbon disulfide ($$\mathrm{CS_2$}$$, molar mass = 76.14 g/mol) and 2.43 g of acetone ($$\mathrm{CH_3COCH_3}$$, molar mass = 58.08 g/mol). If the mole fraction of $$\mathrm{CS_2$} is 0.55 $$and its vapor pressure is 515 Torr, what is the partial pressure of $$\mathrm{CS_2$}$$ above the solution?

$$0.55 \times 515\ \mathrm{Torr} = 283\ \mathrm{Torr}$$

Question 1

Which of the following best describes a solution?

Accepted Answer

A homogenous mixture that contains two or more components, with the solvent present in the larger amount.

Question 2

Which of the following is an example of a gas dissolved in a liquid solution?

Accepted Answer

Club soda (CO$$_2$$ and water)

Question 3

Which statement correctly describes the effect of temperature on the solubility of most solids in water?

Accepted Answer

Solubility of most solids increases with increasing temperature.

Question 4

Which of the following best explains why adding a nonvolatile solute to a solvent lowers the solvent's vapor pressure?

Accepted Answer

The solute particles occupy surface sites, reducing the number of solvent molecules able to escape into the vapor phase.

Question 5

A solution is prepared by dissolving 10.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 500.0 mL of solution. What is the molarity of the solution?

Accepted Answer

$$0.171\ 	ext{M}$$

Question 6

Which of the following statements about the enthalpy of solution ($$\Delta H_{	ext{sol}}) is $$correct?

Accepted Answer

$$\Delta H_{	ext{sol}} is $$the sum of the enthalpy changes for breaking solute-solute, solvent-solvent, and forming solute-solvent interactions.

Question 7

According to Henry's Law, which equation correctly relates the solubility of a gas ($$S_{	ext{gas}}) to $$its partial pressure ($$P_{	ext{gas}}) $$above a solution?

Accepted Answer

$$S_{	ext{gas}} = k_H \cdot P_{	ext{gas}}$$

Question 8

A 1.7 m aqueous solution of ethylene glycol ($$\mathrm{C_2H_6O_2}) is $$prepared. If the freezing point depression constant for water is $$K_f = 1.86\ ^\circ\mathrm{C}\,\mathrm{m}^{-1}$$, what is the freezing point of the solution?

Accepted Answer

$$-3.2\ ^\circ\mathrm{C}$$

Question 9

Which of the following best describes a supersaturated solution?

Accepted Answer

A solution that contains more than the equilibrium amount of solute and is unstable.

Question 10

Which of the following is the correct formula for calculating the osmotic pressure ($$\Pi) of a $$solution?

Accepted Answer

$$\Pi = MRT$$

Question 11

A solution is made by dissolving 0.102 mol of $$\mathrm{Ca(NO_3$)_2} in 0.927 $$mol of water. Assuming complete dissociation, what is the van't Hoff factor ($$i) $$for $$\mathrm{Ca(NO_3$)_2}$$?

Accepted Answer

$$i = 3$$

Question 12

Which of the following best explains why drinking saltwater causes dehydration?

Accepted Answer

Saltwater is hyperosmotic to body fluids, causing water to leave cells by osmosis.

Question 13

Which of the following concentration units is defined as moles of solute per kilogram of solvent?

Accepted Answer

Molality ($$m)$$

Question 14

A solution is prepared by mixing 3.95 g of carbon disulfide ($$\mathrm{CS_2$}$$, molar mass = 76.14 g/mol) and 2.43 g of acetone ($$\mathrm{CH_3COCH_3}$$, molar mass = 58.08 g/mol). If the mole fraction of $$\mathrm{CS_2$} is 0.55 $$and its vapor pressure is 515 Torr, what is the partial pressure of $$\mathrm{CS_2$}$$ above the solution?

Accepted Answer

$$0.55 	imes 515\ \mathrm{Torr} = 283\ \mathrm{Torr}$$

Question 15

Which of the following best describes an ideal solution?

Accepted Answer

A solution in which solute-solvent interactions are similar in strength to solvent-solvent and solute-solute interactions.

Question 16

Which of the following equations correctly expresses the freezing point depression for a solution containing a strong electrolyte?

Accepted Answer

$$\Delta T_f = imK_f$$

Question 17

A nurse must prepare an intravenous (IV) solution that is isotonic with blood plasma. Why is it important that the solution be isotonic?

Accepted Answer

To ensure that red blood cells do not shrink or swell due to osmotic pressure differences.

Question 18

Which of the following statements about colligative properties is correct?

Accepted Answer

Colligative properties depend only on the number of solute particles present.

Chapter 12: Solutions and Their Properties

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