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

13. Liquids, Solids & Intermolecular Forces

Clausius-Clapeyron Equation

General Chemistry

13. Liquids, Solids & Intermolecular Forces

Clausius-Clapeyron Equation

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Multiple Choice

Using the two-point form of the Clausius-Clapeyron equation, calculate the vapor pressure of methanol at 12.0°C given its normal boiling point is 64.6°C and its heat of vaporization is 35.2 kJ/mol.

0.12 atm

1.00 atm

0.35 atm

0.75 atm

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Verified step by step guidance

Identify the two temperatures involved: the normal boiling point (64.6°C) and the temperature at which you want to find the vapor pressure (12.0°C). Convert these temperatures from Celsius to Kelvin by adding 273.15.

Use the two-point form of the Clausius-Clapeyron equation: \( \ln \left( \frac{P_2}{P_1} \right) = -\frac{\Delta H_{vap}}{R} \left( \frac{1}{T_2} - \frac{1}{T_1} \right) \), where \( P_1 \) is the vapor pressure at the normal boiling point (1.00 atm), \( P_2 \) is the vapor pressure at 12.0°C, \( \Delta H_{vap} \) is the heat of vaporization, and \( R \) is the ideal gas constant (8.314 J/mol·K).

Substitute the known values into the equation: \( \Delta H_{vap} = 35200 \) J/mol, \( R = 8.314 \) J/mol·K, \( T_1 = 337.75 \) K, and \( T_2 = 285.15 \) K.

Rearrange the equation to solve for \( P_2 \): \( P_2 = P_1 \times \exp \left( -\frac{\Delta H_{vap}}{R} \left( \frac{1}{T_2} - \frac{1}{T_1} \right) \right) \).

Calculate the expression inside the exponential function and then compute \( P_2 \) to find the vapor pressure of methanol at 12.0°C.