Chemistry Test Solutions 2 — Questions and Answers
Question 1: Which colligative property describes the increase in boiling point when a solute is dissolved in a solvent?
- Vapor pressure lowering
- Boiling point elevation (Correct answer)
- Freezing point depression
- Osmotic pressure
Correct answer: Boiling point elevation
Boiling point elevation occurs because dissolved solute particles lower the vapor pressure, requiring a higher temperature to reach atmospheric pressure.
Question 2: What is the molality of a solution containing 4.0 g of NaOH (molar mass = 40 g/mol) dissolved in 500 g of water?
- 0.1 m
- 0.2 m (Correct answer)
- 0.4 m
- 0.8 m
Correct answer: 0.2 m
Moles of NaOH = 4.0/40 = 0.1 mol; molality = 0.1 mol / 0.500 kg = 0.2 m.
Question 3: A solution that contains less dissolved solute than it could hold at a given temperature is called:
- Supersaturated
- Saturated
- Unsaturated (Correct answer)
- Concentrated
Correct answer: Unsaturated
An unsaturated solution has not reached its maximum solute capacity and can dissolve more solute.
Question 4: Which factor does NOT significantly affect the rate of dissolution of a solid solute in a liquid solvent?
- Stirring the solution
- Increasing temperature
- Color of the solute (Correct answer)
- Particle size of the solute
Correct answer: Color of the solute
Color is a physical property that does not affect dissolution rate; stirring, temperature, and particle size all increase the rate.
Question 5: Henry's Law states that the solubility of a gas in a liquid is:
- Inversely proportional to temperature
- Directly proportional to the partial pressure of the gas (Correct answer)
- Independent of pressure
- Inversely proportional to the molar mass of the gas
Correct answer: Directly proportional to the partial pressure of the gas
Henry's Law: C = kP, where gas solubility increases proportionally with the partial pressure of the gas above the liquid.
Question 6: What type of solution forms when two miscible liquids are mixed together in any proportion?
- Saturated solution
- Ideal solution (Correct answer)
- Supersaturated solution
- Colloidal dispersion
Correct answer: Ideal solution
An ideal solution forms when two miscible components mix in any ratio with intermolecular forces similar to the pure components.
Question 7: The van't Hoff factor (i) for a 0.1 m MgCl₂ solution is approximately:
- 1
- 2
- 3 (Correct answer)
- 4
Correct answer: 3
MgCl₂ dissociates into 3 ions (1 Mg²⁺ and 2 Cl⁻), giving a van't Hoff factor of approximately 3.
Chemistry Test Solutions 2
Which colligative property describes the increase in boiling point when a solute is dissolved in a solvent?