Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

14. Solutions

Freezing Point Depression

General Chemistry

14. Solutions

Freezing Point Depression

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Multiple Choice

What is the freezing point of a solution that contains 50.0 g of FeBr₃ in 200.0 g of water, given that the freezing point depression constant (Kf) for water is 1.86 °C/m?

-3.72 °C

-5.58 °C

-1.86 °C

0.00 °C

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Verified step by step guidance

First, calculate the molar mass of FeBr₃. The molar mass is the sum of the atomic masses of iron (Fe) and bromine (Br). Use the periodic table to find these values: Fe = 55.85 g/mol, Br = 79.90 g/mol. Since there are three bromine atoms, the molar mass of FeBr₃ is:

55.85 + 3 \times 79.90

g/mol.

Next, determine the number of moles of FeBr₃ in the solution. Use the formula:

n = \frac{mass}{molar mass}

. Substitute the mass of FeBr₃ (50.0 g) and the molar mass calculated in the previous step to find the moles.

Calculate the molality of the solution. Molality (m) is defined as moles of solute per kilogram of solvent. Use the formula:

m = \frac{moles of solute}{kg of solvent}

. Convert the mass of water (200.0 g) to kilograms and use the moles of FeBr₃ from the previous step.

Determine the van't Hoff factor (i) for FeBr₃. Since FeBr₃ dissociates into four ions (Fe³⁺ and 3 Br^-), the van't Hoff factor is 4.

Finally, calculate the freezing point depression using the formula:

ΔT = Kf \times m \times i

. Substitute the values for Kf (1.86 °C/m), molality, and the van't Hoff factor to find the change in freezing point. Subtract this value from the normal freezing point of water (0.00 °C) to find the freezing point of the solution.