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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4:31 minutes

Problem 32

Textbook Question

What is the smallest straight-chain alkane that is a liquid at room temperature (which is about 25 °C)?

Verified step by step guidance

Understand the problem: We are tasked with identifying the smallest straight-chain alkane that exists as a liquid at room temperature (approximately 25 °C). Alkanes are hydrocarbons with the general formula C_nH_2n+2, and their physical state depends on molecular size and intermolecular forces.

Recall the trend: The physical state of alkanes (gas, liquid, or solid) at room temperature depends on their molecular weight and boiling point. Smaller alkanes (with fewer carbon atoms) tend to be gases, while larger alkanes are liquids or solids due to stronger London dispersion forces.

Identify the boiling point range: For an alkane to be a liquid at room temperature, its boiling point must be between 25 °C and 100 °C. Alkanes with boiling points below 25 °C are gases, and those above 100 °C are typically liquids or solids.

Consult boiling point data: Look up the boiling points of straight-chain alkanes (e.g., methane, ethane, propane, butane, pentane, hexane, etc.) to determine the smallest alkane whose boiling point falls within the liquid range at room temperature.

Conclude the smallest alkane: Based on the boiling point data, identify the straight-chain alkane with the lowest molecular weight that meets the criteria of being a liquid at room temperature.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alkanes

Alkanes are saturated hydrocarbons consisting only of carbon and hydrogen atoms, connected by single bonds. They follow the general formula CnH2n+2, where 'n' is the number of carbon atoms. Alkanes can be straight-chain or branched, and their physical properties, such as boiling and melting points, vary with molecular size.

Boiling Point

The boiling point of a substance is the temperature at which its vapor pressure equals the external pressure, causing it to change from liquid to gas. For alkanes, the boiling point increases with molecular weight due to greater van der Waals forces. Understanding boiling points helps determine the state of an alkane at a given temperature.

State of Matter at Room Temperature

Room temperature, typically around 25 °C, is a standard reference point for assessing the physical state of substances. Alkanes with fewer than five carbon atoms (like methane and ethane) are gases at this temperature, while those with five or more carbons are liquids. Identifying the smallest alkane that is liquid at room temperature requires knowledge of these state changes.