Hydrophilic substances O a) are soluble in nonpolar solvents. Ob) generally do not hydrogen bond. c) are soluble in water. d) are insoluble in water. e) are immiscible in water. Which of the following regarding colligative properties of a solution is NOT correct? a) The change in the boiling point of a solvent due to the presence of a solute is a colligative property. b) Vapor pressure reduction is a colligative property. Colligative properties depend on the concentration of the particles dissolved in the solvent. d) The freezing point of a solution increases as the concentration of solute increases e) The temperature range over which a solution remains liquid is larger than that of the pure solvent arises due to the presence of solute particles. Which of the following statements regarding the solubility of ionic compounds in water is NOT correct? a) Al2O3 is probably less soluble in water than Na2O in part because its lattice energy is more negative. b) Water can more readily separate and hydrate highly charged ions in ionic solids than ions with smaller charges. c) Ionic compounds with very large negative lattice energies typically show limited solubility in water. d) Ba(OH)2 is probably more soluble in water than Ca(OH)2 in part because its lattice energy is less negative. e) Ionic compounds containing relatively large ions generally show higher solubility in water.
The Correct Answer and Explanation is:
1. Hydrophilic substances:
Correct answer: c) are soluble in water.
2. Which of the following regarding colligative properties is NOT correct?
Correct answer: d) The freezing point of a solution increases as the concentration of solute increases.
3. Which of the following regarding the solubility of ionic compounds in water is NOT correct?
Correct answer: b) Water can more readily separate and hydrate highly charged ions in ionic solids than ions with smaller charges.
Explanation
Hydrophilic substances are those that interact favorably with water, a polar solvent. These substances are usually polar themselves or capable of hydrogen bonding, making them soluble in water (choice c). In contrast, nonpolar substances are hydrophobic and do not dissolve well in water. Therefore, choices such as (a), (d), and (e) are incorrect.
Colligative properties depend only on the number of solute particles in a given quantity of solvent, not their identity. These include boiling point elevation, freezing point depression, vapor pressure lowering, and osmotic pressure. The freezing point of a solution actually decreases, not increases, with the addition of solute because the solute particles disrupt the formation of the solid phase. Hence, choice (d) is the incorrect statement.
Regarding solubility of ionic compounds in water, lattice energy and hydration energy play key roles. Lattice energy is the energy required to separate one mole of an ionic solid into gaseous ions; the more negative it is, the harder it is to dissolve the compound. Hydration energy is the energy released when ions are solvated by water molecules. Small, highly charged ions (e.g., Al³⁺) have strong electrostatic forces that make their separation difficult, thus reducing solubility. Statement (b) is incorrect because water has more difficulty, not ease, in separating and hydrating highly charged ions due to their strong lattice energies and high electrostatic attraction. Larger ions and lower lattice energies usually correlate with greater solubility (e.g., Ba²⁺ vs Ca²⁺). Hence, the other options in that question are accurate.
These principles are fundamental to understanding solution chemistry and physical properties influenced by solute-solvent interactions.
