Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

2. Molecular Representations

Intermolecular Forces

Organic Chemistry

2. Molecular Representations

Intermolecular Forces

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Multiple Choice

Why do branched alkanes have a lower boiling point than linear alkanes with the same molecular formula?

Branched alkanes have weaker hydrogen bonding interactions than linear alkanes.

They don't. Branched alkanes have higher boiling points than linear alkanes with the same molecular formula.

Branched alkanes have a smaller surface area relative to linear alkanes, which leads to weaker dispersion forces.

Branched alkanes have weaker dipoles, which leads to fewer dipole-dipole interactions.

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Verified step by step guidance

Understand the concept of boiling point: The boiling point of a substance is the temperature at which its vapor pressure equals the external pressure. It is influenced by the strength of intermolecular forces present in the substance.

Identify the types of intermolecular forces in alkanes: Alkanes are nonpolar molecules, so the primary intermolecular forces are London dispersion forces, which are weak and arise from temporary dipoles.

Compare the surface area of branched vs. linear alkanes: Linear alkanes have a larger surface area compared to their branched counterparts. A larger surface area allows for more contact between molecules, leading to stronger dispersion forces.

Relate surface area to boiling point: Since linear alkanes have stronger dispersion forces due to their larger surface area, they require more energy (higher temperature) to overcome these forces, resulting in a higher boiling point.

Conclude why branched alkanes have lower boiling points: Branched alkanes have a smaller surface area, leading to weaker dispersion forces and thus a lower boiling point compared to linear alkanes with the same molecular formula.