Podcast
Questions and Answers
Which scenario would exhibit the most significant ion pairing?
Which scenario would exhibit the most significant ion pairing?
- A 0.001 m solution of NaCl
- A 0.1 m solution of KCl
- A 0.05 m solution of MgSO4 (correct)
- A 0.01 m solution of glucose
Why does adding salt to water impact the boiling point?
Why does adding salt to water impact the boiling point?
- Salt lowers the energy of the water molecules.
- Salt facilitates the water molecules’ kinetic energy.
- Salt increases the vapor pressure of the solution, decreasing the boiling point.
- Salt decreases the vapor pressure of the solution, increasing the boiling point. (correct)
A solution of 25.0 g of glucose in 200 g of water will result in a boiling point of approximately:
A solution of 25.0 g of glucose in 200 g of water will result in a boiling point of approximately:
- 100.36 °C (correct)
- 99.64 °C
- 100.72 °C
- 100.19 °C
What will be the approximate freezing point of a 0.050 m MgCl2 aqueous solution, assuming complete dissociation?
What will be the approximate freezing point of a 0.050 m MgCl2 aqueous solution, assuming complete dissociation?
A 0.546 g sample of a hormone was dissolved in 15.0 g of benzene, causing a freezing point depression of 0.240°C. What is the molar mass of the hormone, given that the freezing point depression constant of benzene is approximately 5.12 °C⋅kg/mol?
A 0.546 g sample of a hormone was dissolved in 15.0 g of benzene, causing a freezing point depression of 0.240°C. What is the molar mass of the hormone, given that the freezing point depression constant of benzene is approximately 5.12 °C⋅kg/mol?
Which of the following correctly describes the effect of a nonvolatile solute on the vapor pressure of a solution?
Which of the following correctly describes the effect of a nonvolatile solute on the vapor pressure of a solution?
Why does the boiling point of a solution containing a nonvolatile solute increase?
Why does the boiling point of a solution containing a nonvolatile solute increase?
A solution is made by mixing a non-volatile solute with a volatile solvent. Which of the following statements is FALSE about the colligative properties of this solution?
A solution is made by mixing a non-volatile solute with a volatile solvent. Which of the following statements is FALSE about the colligative properties of this solution?
Which statement best describes the relationship between solute concentration and colligative property changes?
Which statement best describes the relationship between solute concentration and colligative property changes?
What is the fundamental difference that must be considered when examining colligative properties of electrolyte solutions versus non-electrolyte solutions?
What is the fundamental difference that must be considered when examining colligative properties of electrolyte solutions versus non-electrolyte solutions?
If a nonvolatile solute is added to a volatile solvent, what happens to the rate of vaporization and the rate of condensation?
If a nonvolatile solute is added to a volatile solvent, what happens to the rate of vaporization and the rate of condensation?
A solution has a higher boiling point than the pure solvent. Which of the following changes would be expected to further increase the boiling point of this solution?
A solution has a higher boiling point than the pure solvent. Which of the following changes would be expected to further increase the boiling point of this solution?
Which of the following options describes the normal freezing point?
Which of the following options describes the normal freezing point?
A solution of NaCl in water displays a boiling point of 101.04 °C. If the Kb of water is 0.512 °C·kg/mol, and assuming complete dissociation and no ion pairing, what is the molality of the solution?
A solution of NaCl in water displays a boiling point of 101.04 °C. If the Kb of water is 0.512 °C·kg/mol, and assuming complete dissociation and no ion pairing, what is the molality of the solution?
Which of the following solutions, assuming the same molality for all, will exhibit the lowest freezing point?
Which of the following solutions, assuming the same molality for all, will exhibit the lowest freezing point?
A 0.2 molal solution of a certain salt shows a freezing point depression of 0.744 °C in water. Given the Kf of water as 1.86 °C·kg/mol, what is the van’t Hoff factor? Assume no ion-pairing.
A 0.2 molal solution of a certain salt shows a freezing point depression of 0.744 °C in water. Given the Kf of water as 1.86 °C·kg/mol, what is the van’t Hoff factor? Assume no ion-pairing.
Which of the following statements regarding ion pairing in solutions is correct?
Which of the following statements regarding ion pairing in solutions is correct?
What is the boiling point of a 0.25 molal solution of $Na_3PO_4$ in water, given that the Kb for water is 0.512 °C·kg/mol? Assume complete dissociation and no ion pairing.
What is the boiling point of a 0.25 molal solution of $Na_3PO_4$ in water, given that the Kb for water is 0.512 °C·kg/mol? Assume complete dissociation and no ion pairing.
Which of the following will have the smallest effect on the freezing point of water for a solution of equal molality?
Which of the following will have the smallest effect on the freezing point of water for a solution of equal molality?
A solution of a salt in water initially registers a van't Hoff factor of 3, but, as the solution is diluted, the van't Hoff factor is observed to approach 4. Which of the following salts did the chemist most likely use?
A solution of a salt in water initially registers a van't Hoff factor of 3, but, as the solution is diluted, the van't Hoff factor is observed to approach 4. Which of the following salts did the chemist most likely use?
If 2 moles of $MgCl_2$ are dissolved in water, which statement is true about the resulting solution, assuming complete dissociation?
If 2 moles of $MgCl_2$ are dissolved in water, which statement is true about the resulting solution, assuming complete dissociation?
Flashcards
Colligative property
Colligative property
A property of a solution that depends on the number of solute particles, not their type.
Boiling-point elevation
Boiling-point elevation
The boiling point of a solution is higher than the boiling point of the pure solvent.
Freezing-point depression
Freezing-point depression
The freezing point of a solution is lower than the freezing point of the pure solvent.
Nonelectrolyte
Nonelectrolyte
Signup and view all the flashcards
Electrolyte
Electrolyte
Signup and view all the flashcards
Vapor pressure of pure solvent
Vapor pressure of pure solvent
Signup and view all the flashcards
Vapor pressure of solution
Vapor pressure of solution
Signup and view all the flashcards
Vaporization
Vaporization
Signup and view all the flashcards
van't Hoff factor (i)
van't Hoff factor (i)
Signup and view all the flashcards
Ion pairing
Ion pairing
Signup and view all the flashcards
Molar Mass Determination Using Colligative Properties
Molar Mass Determination Using Colligative Properties
Signup and view all the flashcards
Boiling Point Elevation (ΔTb)
Boiling Point Elevation (ΔTb)
Signup and view all the flashcards
Molality (m)
Molality (m)
Signup and view all the flashcards
Molal Boiling-Point Elevation Constant (Kb)
Molal Boiling-Point Elevation Constant (Kb)
Signup and view all the flashcards
Freezing Point Depression (ΔTf)
Freezing Point Depression (ΔTf)
Signup and view all the flashcards
Molal Freezing-Point Depression Constant (Kf)
Molal Freezing-Point Depression Constant (Kf)
Signup and view all the flashcards
Colligative Properties
Colligative Properties
Signup and view all the flashcards
Study Notes
Colligative Properties
- Colligative properties are physical properties of a solution that depend on the number of solute particles dissolved in the solution, not the type of solute.
- These properties include boiling point elevation and freezing point depression.
Types of Solutions
- Solutions can be classified into two types:
- Solutions where the solute is a nonelectrolyte(non-dissociating)
- Solutions where the solute is an electrolyte (dissociating)
Boiling Point and Freezing Point of Solutions
-
The normal boiling point of a liquid is the temperature where the vapor pressure equals the atmospheric pressure.
-
Boiling-point elevation (∆Tb): the boiling point of a solution is higher than the boiling point of the pure solvent.
-
The normal freezing point is the temperature at which a liquid turns into a solid at atmospheric pressure.
-
Freezing-point depression (∆Tf): the freezing point of a solution is lower than the freezing point of the pure solvent.
Vapor Pressure of Solutions
- The vapor pressure of a solution is lower than the vapor pressure of the pure solvent due to the presence of solute particles interfering with the solvent's ability to vaporize.
Boiling-Point Elevation of Solutions
- A solution's vapor pressure is lowered when a solute is added, causing the solution to require a higher temperature to reach atmospheric pressure. This elevation is referred to as boiling-point elevation.
- The equation used to calculate boiling point elevation is: ∆T = iKbm, where ∆T is the boiling-point elevation, T(solution)-T(solvent) = iKb m (I= van't Hoff factor) (Kb = molal boiling-point elevation constant,) and m = molality of the solution.
Freezing-Point Depression of Solutions
- The addition of a solute to a solvent lowers the freezing point due to the interference of the solute particles disrupting the formation of the solid phase.
- The equation for freezing-point depression is ∆T = iKfm, where ∆T is the freezing-point depression, T(solvent)-T(solution) = iKf m (I= van't Hoff factor) (Kf = molal freezing-point depression constant), and m = molality of the solution.
van't Hoff Factor (i)
- The van't Hoff factor (i) represents the ratio of moles of particles in solution to moles of solute dissolved.
- For non-electrolytes, i is equal to 1.
- For electrolytes, i is greater than 1, as the solute dissociates into multiple ions in solution.
- The expected value of i can be determined by the number of ions produced per formula unit (assuming complete dissociation and no ion pairing).
Ion Pairing in Electrolyte Solutions
- Ion pairing occurs in electrolyte solutions, where cations and anions attract each other, temporarily forming pairs and reducing the number of independent particles.
- Ion pairing is more pronounced in concentrated solutions, becoming less significant as the solutions become more dilute.
Examples and Applications
- Boiling point elevation and freezing point depression are utilized in various applications, including antifreeze in cars and de-icing roads.
- These properties can be used to determine the unknown molar mass of a substance.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
