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

19. Chemical Thermodynamics

Gibbs Free Energy Calculations

General Chemistry

19. Chemical Thermodynamics

Gibbs Free Energy Calculations

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Multiple Choice

For the vaporization of benzene, ΔHvap = 30.7 kJ/mol and ΔSvap = 87.0 J/(K·mol). Does benzene boil at 75 °C and 1 atm pressure?

No, because the enthalpy change is too high at this temperature.

Yes, because the entropy change is positive at this temperature.

Yes, because the Gibbs free energy change is negative at this temperature.

No, because the Gibbs free energy change is positive at this temperature.

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Verified step by step guidance

First, understand that the boiling point of a substance is the temperature at which its vapor pressure equals the external pressure. At this point, the Gibbs free energy change (ΔG) for the phase transition is zero.

Use the Gibbs free energy equation: ΔG = ΔH - TΔS, where ΔG is the change in Gibbs free energy, ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy.

Convert the given temperature from Celsius to Kelvin by adding 273.15. So, T = 75 + 273.15 K.

Substitute the given values into the Gibbs free energy equation: ΔG = 30.7 kJ/mol - (T in Kelvin) * 87.0 J/(K·mol). Note that you need to convert ΔHvap from kJ/mol to J/mol by multiplying by 1000.

Determine if ΔG is negative, zero, or positive. If ΔG is zero, benzene boils at this temperature and pressure. If ΔG is negative, the process is spontaneous, indicating that benzene can boil at this temperature and pressure. If ΔG is positive, benzene does not boil at this temperature and pressure.