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

Previous problemNext problem

Struggling with General Chemistry?

Join thousands of students who trust us to help them ace their exams!Watch the first video

Multiple Choice

Determine the freezing point of a solution that contains 78.8 g of naphthalene (C10H8, molar mass = 128.16 g/mol) dissolved in 722 mL of benzene (density = 0.877 g/mL). Pure benzene has a melting point of 5.50°C and a freezing point depression constant of 4.90°C/m. What is the new freezing point of the solution?

0.00°C

3.45°C

1.23°C

5.50°C

Previous problemNext problem

Verified step by step guidance

Calculate the moles of naphthalene (C10H8) using its mass and molar mass. Use the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Determine the mass of benzene using its volume and density. Use the formula: \( \text{mass} = \text{volume} \times \text{density} \).

Convert the mass of benzene to kilograms to use in the molality calculation. Remember that 1 g = 0.001 kg.

Calculate the molality of the solution using the formula: \( \text{molality} = \frac{\text{moles of solute}}{\text{kilograms of solvent}} \).

Use the freezing point depression formula: \( \Delta T_f = i \cdot K_f \cdot m \), where \( i \) is the van't Hoff factor (which is 1 for naphthalene), \( K_f \) is the freezing point depression constant, and \( m \) is the molality. Subtract \( \Delta T_f \) from the pure benzene's freezing point to find the new freezing point.