Properties of Solutions Study Notes

Concept: When a drop of food coloring is dispersed in water, it is essential to determine whether the entropy of the system is increasing or decreasing.
Options:
- a. Increasing
- b. Decreasing

Question: Why doesn’t NaCl dissolve in nonpolar solvents such as hexane (C₆H₄)?
Explanations:
- a. Polar Nature: NaCl is a polar covalent molecule; solvents dissolve solutes with similar intermolecular forces.
- b. Neutral Substance: NaCl is neutral and is unattracted to nonpolar hexane.
- c. Ionic Character: NaCl's ionic bonds cannot be disrupted by nonpolar interactions.
- d. Size of Ions: NaCl contains large ions that are challenging to separate and dissolve in any solvent.

Label Processes:
- (a) Breaking Solvent-Solvent Interactions: Endothermic
- (b) Forming Solvent-Solute Interactions: Exothermic
Options:
- a. Endothermic
- b. Exothermic
- c. Both processes labeled

Concept: What happens when a solute is added to a saturated solution?
Options:
- a. More solute dissolves.
- b. The additional solute does not dissolve, and some of the original solute precipitates out.
- c. The additional solute does not dissolve, ensuring the solution remains saturated.
- d. Temperature changes allow some solute to dissolve.

Question: If the hydrogens on the OH groups in glucose were replaced with methyl groups (CH₃), how would this affect water solubility?
Expected Outcomes:
- a. Higher solubility
- b. Lower solubility
- c. About the same solubility
Example:
- Cyclohexane (C₆H₁₂): Insoluble in water due to lack of polar OH groups.
- Glucose: Soluble due to hydrogen bonding with H₂O via OH groups.

Question: Given a solution of SO₂ in water with 0.00023 g of SO₂ per liter, calculate concentration in ppm and ppb.
Options:
- a. 2.3 ppm; 2300 ppb
- b. 23 ppm; 2.3 × 10⁴ ppb
- c. 0.23 ppm: 230 ppb
- d. 230 ppm; 2.3 × 10⁵ ppb

Question: For a very dilute aqueous solution, compare molality and molarity.
Options:
- a. Molality will be greater than its molarity.
- b. Molality will be nearly the same as its molarity.
- c. Molality will be smaller than its molarity.

Question: Does adding 1 mol of NaCl to 1 kg of water lower its vapor pressure to the same extent, lesser extent, or greater extent than adding 1 mol of C₆H₁₂O₆ to the same mass of water?
Options:
- a. Same extent (equal moles)
- b. Lesser extent (more grams of C₆H₁₂O₆)
- c. Greater extent (depends on total solute concentration)

Question: A solute causes a boiling point increase of 0.51 °C. Does this imply a concentration of 1.0 m?
Options:
- a. Yes
- b. No
- c. Depends on solute characteristics (strong or weak electrolyte)
- d. Depends on solute type (nonpolar, nonelectrolyte)

Table 13.3: Constants for various solvents

Solvent	Normal Boiling Point (°C)	Normal Freezing Point (°C)	K₁ (°C/m)	K₁₂ (°C/m)
Water, H₂O	100.0	0.0	0.51	1.86
Benzene, C₆H₆	80.1	5.5	2.53	5.12
Ethanol, C₂H₅OH	78.4	-114.6	1.22	1.99
Carbon tetrachloride, CCl₄	76.8	-22.3	5.02	29.8
Chloroform, CHCl₃	61.2	-63.5	3.63	4.68

Isotonic and Hypotonic Solutions

Question: Of two KBr solutions (0.50 m and 0.20 m), which is hypotonic to the other?
Options:
- a. The 0.20 m KCl solution is hypotonic compared to the 0.50 m KCl solution.
- b. The 0.50 m KCl solution is hypotonic compared to the 0.20 m KCl solution.
- c. Neither is hypotonic to the other.
- d. They are isotonic solutions.

Question: Is the osmotic pressure of a 0.10 M solution of NaCl greater than, equal to, or less than that of a 0.10 M solution of KBr?
Options:
- a. Greater
- b. Equal
- c. Less

Question: Do hydrophilic groups of proteins in the hydrophobic lipid bilayer face the lipid "solvent"?
Options:
- a. Yes, they face outward.
- b. No, they are repelled by lipid hydrophobicity.