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

A solvent has a freezing point of 10.1°C and a freezing point depression constant of 6.16°C/m. If a solution, made by dissolving 1.218 g of an unknown solute into 25.0 g of the solvent, has a freezing point of 8.8°C, what is the molar mass of the solute?

110.3 g/mol

92.1 g/mol

58.5 g/mol

75.0 g/mol

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Verified step by step guidance

Identify the change in freezing point by subtracting the freezing point of the solution from the freezing point of the pure solvent: ΔT_f = 10.1°C - 8.8°C.

Use the formula for freezing point depression: ΔT_f = i * K_f * m, where i is the van't Hoff factor (assumed to be 1 for non-electrolytes), K_f is the freezing point depression constant, and m is the molality of the solution.

Calculate the molality (m) using the formula: m = ΔT_f / K_f. Substitute the values for ΔT_f and K_f to find the molality.

Determine the number of moles of solute using the formula: moles = molality * mass of solvent (in kg). Convert the mass of the solvent from grams to kilograms before substituting.

Calculate the molar mass of the solute using the formula: molar mass = mass of solute (in grams) / moles of solute. Substitute the mass of the solute and the moles calculated in the previous step.