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

1. A Review of General Chemistry

Degrees of Unsaturation

Organic Chemistry

1. A Review of General Chemistry

Degrees of Unsaturation

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3:48 minutes

Problem 42

Textbook Question

What is the molecular formula of a hydrocarbon that has 1 triple bond, 2 double bonds, 1 ring, and 32 carbons?

Verified step by step guidance

Step 1: Recall the general formula for a hydrocarbon. Hydrocarbons are composed of carbon (C) and hydrogen (H). The molecular formula depends on the degree of unsaturation, which includes double bonds, triple bonds, and rings.

Step 2: Use the degree of unsaturation formula to account for the structural features. The degree of unsaturation (DU) is calculated as: $ DU = \frac{2C + 2 - H}{2} $, where $ C $ is the number of carbons, and $ H $ is the number of hydrogens. Each double bond, triple bond, or ring contributes to the degree of unsaturation.

Step 3: For this problem, the hydrocarbon has 1 triple bond, 2 double bonds, and 1 ring. Each double bond contributes 1 degree of unsaturation, each triple bond contributes 2 degrees of unsaturation, and each ring contributes 1 degree of unsaturation. Add these contributions: $ 1 (triple bond) + 2 (double bonds) + 1 (ring) = 4 $.

Step 4: Use the degree of unsaturation to determine the number of hydrogens. For a hydrocarbon with 32 carbons ($ C = 32 $) and a degree of unsaturation of 4, substitute into the formula: $ H = 2C + 2 - 2(DU) $. This simplifies to $ H = 2(32) + 2 - 2(4) $.

Step 5: Write the molecular formula. After determining the number of hydrogens ($ H $), the molecular formula will be $ C_{32}H_x $, where $ x $ is the calculated number of hydrogens from Step 4.

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Key Concepts

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

Hydrocarbon Structure

Hydrocarbons are organic compounds consisting solely of carbon (C) and hydrogen (H) atoms. Their structure can vary significantly based on the types of bonds (single, double, or triple) and the presence of rings. Understanding the basic structure of hydrocarbons is essential for determining their molecular formula, as the arrangement and types of bonds influence the overall composition.

Degree of Unsaturation

The degree of unsaturation indicates the total number of rings and multiple bonds (double or triple) in a hydrocarbon. Each double bond or ring contributes one degree of unsaturation, while each triple bond contributes two. This concept is crucial for calculating the molecular formula, as it helps determine how many hydrogen atoms are present relative to the number of carbon atoms.

Molecular Formula Calculation

The molecular formula of a compound represents the number and types of atoms present. For hydrocarbons, the general formula is CnH(2n+2) for saturated compounds. However, for unsaturated hydrocarbons, adjustments must be made based on the degree of unsaturation. In this case, the presence of 1 triple bond, 2 double bonds, and 1 ring must be accounted for to derive the correct molecular formula from the given number of carbon atoms.