Select The Correct Answer.Which Of These Solutions Has The Highest Freezing Point?A. 1.0 M Molecular Sucrose $\left( C_{12}H_{22}O_{11} \right)$ B. 1.0 M Ionic Sodium Chloride $(NaCl)$ C. 1.0 M Ionic Calcium Bromide $\left(
When it comes to determining the solution with the highest freezing point, we need to consider the properties of the solutes and their effects on the freezing point of the solvent. In this article, we will explore the concept of freezing point depression and how it applies to different types of solutions.
Understanding Freezing Point Depression
Freezing point depression is a phenomenon where the addition of a solute to a solvent lowers the freezing point of the solution. This occurs because the solute particles disrupt the formation of ice crystals in the solvent, making it more difficult for the solution to freeze. The extent of freezing point depression depends on the concentration of the solute and its ability to interact with the solvent molecules.
Types of Solutions
There are two main types of solutions: molecular and ionic. Molecular solutions are formed when a non-polar solute is dissolved in a non-polar solvent, resulting in weak intermolecular forces between the solute and solvent molecules. Ionic solutions, on the other hand, are formed when an ionic solute is dissolved in a polar solvent, resulting in strong electrostatic forces between the solute and solvent molecules.
Molecular Sucrose Solution
A 1.0 M molecular sucrose solution is formed when sucrose molecules are dissolved in water. Sucrose is a non-polar molecule with a molecular formula of C12H22O11. In this solution, the sucrose molecules interact with the water molecules through weak intermolecular forces, such as van der Waals forces and hydrogen bonding.
Ionic Sodium Chloride Solution
A 1.0 M ionic sodium chloride solution is formed when sodium chloride is dissolved in water. Sodium chloride is an ionic compound with a molecular formula of NaCl. In this solution, the sodium and chloride ions interact with the water molecules through strong electrostatic forces, resulting in a highly polarized solution.
Ionic Calcium Bromide Solution
A 1.0 M ionic calcium bromide solution is formed when calcium bromide is dissolved in water. Calcium bromide is an ionic compound with a molecular formula of CaBr2. In this solution, the calcium and bromide ions interact with the water molecules through strong electrostatic forces, resulting in a highly polarized solution.
Comparing the Solutions
Now that we have discussed the properties of each solution, let's compare them in terms of their freezing points. According to the concept of freezing point depression, the solution with the highest freezing point will be the one with the least amount of solute particles disrupting the formation of ice crystals.
Freezing Point Depression Constants
The freezing point depression constant (Kf) is a measure of the extent of freezing point depression caused by a particular solute. The Kf value for water is 1.86 K/m. The Kf values for the three solutions are:
- Molecular sucrose: 0.51 K/m
- Ionic sodium chloride: 1.86 K/m
- Ionic calcium bromide: 3.71 K/m
Determining the Solution with the Highest Freezing Point
Based on the Kf values, we can determine that the ionic calcium bromide solution has the highest freezing point. This is because the calcium and bromide ions have a strong electrostatic interaction with the water molecules, resulting in a highly polarized solution that disrupts the formation of ice crystals to a lesser extent.
Conclusion
In conclusion, the solution with the highest freezing point is the ionic calcium bromide solution. This is due to the strong electrostatic interaction between the calcium and bromide ions and the water molecules, resulting in a highly polarized solution that disrupts the formation of ice crystals to a lesser extent. The molecular sucrose solution has a lower freezing point due to the weak intermolecular forces between the sucrose molecules and the water molecules. The ionic sodium chloride solution has a moderate freezing point due to the strong electrostatic interaction between the sodium and chloride ions and the water molecules.
References
- Atkins, P. W., & De Paula, J. (2010). Physical chemistry (9th ed.). Oxford University Press.
- Brown, T. L., LeMay, H. E., Bursten, B. E., & Murphy, C. (2012). Chemistry: The Central Science (12th ed.). Pearson Education.
- Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2011). General chemistry: Principles and modern applications (10th ed.). Pearson Education.
Frequently Asked Questions (FAQs) about Freezing Point Depression ====================================================================
In this article, we will address some of the most common questions related to freezing point depression and its applications.
Q: What is freezing point depression?
A: Freezing point depression is a phenomenon where the addition of a solute to a solvent lowers the freezing point of the solution. This occurs because the solute particles disrupt the formation of ice crystals in the solvent, making it more difficult for the solution to freeze.
Q: What are the factors that affect freezing point depression?
A: The factors that affect freezing point depression include:
- Concentration of the solute: The higher the concentration of the solute, the greater the freezing point depression.
- Type of solute: Ionic solutes tend to have a greater freezing point depression than molecular solutes.
- Temperature: The freezing point depression is greater at lower temperatures.
Q: What are some common applications of freezing point depression?
A: Some common applications of freezing point depression include:
- Antifreeze: Freezing point depression is used in antifreeze to prevent the engine from freezing in cold temperatures.
- Pharmaceuticals: Freezing point depression is used in some pharmaceutical applications to prevent the degradation of the active ingredients.
- Food preservation: Freezing point depression is used in some food preservation methods to prevent the growth of microorganisms.
Q: Can freezing point depression be used to determine the concentration of a solution?
A: Yes, freezing point depression can be used to determine the concentration of a solution. By measuring the freezing point of the solution, you can calculate the concentration of the solute.
Q: What are some common mistakes to avoid when working with freezing point depression?
A: Some common mistakes to avoid when working with freezing point depression include:
- Not accounting for the temperature of the solution: The freezing point depression is greater at lower temperatures.
- Not using the correct concentration of the solute: The freezing point depression is greater at higher concentrations of the solute.
- Not using the correct type of solute: Ionic solutes tend to have a greater freezing point depression than molecular solutes.
Q: Can freezing point depression be used to determine the type of solute?
A: Yes, freezing point depression can be used to determine the type of solute. By measuring the freezing point of the solution, you can determine whether the solute is ionic or molecular.
Q: What are some real-world examples of freezing point depression?
A: Some real-world examples of freezing point depression include:
- Antifreeze: Freezing point depression is used in antifreeze to prevent the engine from freezing in cold temperatures.
- Pharmaceuticals: Freezing point depression is used in some pharmaceutical applications to prevent the degradation of the active ingredients.
- Food preservation: Freezing point depression is used in some food preservation methods to prevent the growth of microorganisms.
Q: Can freezing point depression be used to determine the purity of a solution?
A: Yes, freezing point depression can be used to determine the purity of a solution. By measuring the freezing point of the solution, you can determine whether the solution is pure or contains impurities.
Conclusion
In conclusion, freezing point depression is a phenomenon that occurs when a solute is added to a solvent, lowering the freezing point of the solution. It is an important concept in chemistry and has many practical applications. By understanding the factors that affect freezing point depression, you can use it to determine the concentration of a solution, the type of solute, and the purity of a solution.