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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Problem 4c,d

Textbook Question

Determine the degree of unsaturation for hydrocarbons with the following molecular formulas:
c. C₁₂H₂₀
d. C₄₀H₅₆

Verified step by step guidance

Step 1: Recall the formula for calculating the degree of unsaturation (also known as the index of hydrogen deficiency, IHD). The formula is: IHD = (2C + 2 - H)/2, where C is the number of carbon atoms, and H is the number of hydrogen atoms. This formula assumes the molecule contains only carbon and hydrogen.

Step 2: For part (c), substitute the values for C = 12 and H = 20 into the formula. Write the expression as: IHD = (2(12) + 2 - 20)/2.

Step 3: Simplify the expression for part (c) step by step. First, calculate the term 2(12), then add 2, subtract 20, and finally divide the result by 2 to determine the degree of unsaturation for C12H20.

Step 4: For part (d), substitute the values for C = 40 and H = 56 into the formula. Write the expression as: IHD = (2(40) + 2 - 56)/2.

Step 5: Simplify the expression for part (d) step by step. First, calculate the term 2(40), then add 2, subtract 56, and finally divide the result by 2 to determine the degree of unsaturation for C40H56.

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Key Concepts

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

Degree of Unsaturation

The degree of unsaturation (DU) indicates the total number of rings and multiple bonds (double or triple) present in a hydrocarbon molecule. It can be calculated using the formula DU = (2C + 2 - H)/2, where C is the number of carbon atoms and H is the number of hydrogen atoms. A higher degree of unsaturation suggests more rings or multiple bonds, which affects the molecule's reactivity and stability.

Hydrocarbon Structure

Hydrocarbons are organic compounds consisting solely of carbon (C) and hydrogen (H) atoms. They can be classified into aliphatic (alkanes, alkenes, alkynes) and aromatic compounds. Understanding the structure of hydrocarbons is essential for determining their properties, reactivity, and the implications of their degree of unsaturation.

Molecular Formula Interpretation

A molecular formula provides the number of each type of atom in a molecule, which is crucial for calculating the degree of unsaturation. For example, in the formulas C12H20 and C40H56, the number of carbon and hydrogen atoms directly influences the DU calculation. Interpreting these formulas correctly allows chemists to predict the presence of rings or multiple bonds in the compound.

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Related Practice

Textbook Question

What is the index of hydrogen deficiency for each of the following molecular formulas?

(e) C₆H₁₂O₂

Textbook Question

What is the index of hydrogen deficiency for each of the following molecular formulas?

(b) C₁₂H₁₁NO₃

Textbook Question

Calculate the index of hydrogen deficiency for the following molecules.

(c)

Textbook Question

For each molecular formula, represent all constitutional isomers using line-angle drawings.

Textbook Question

Several studies have shown that β-carotene, a precursor of vitamin A, may play a role in preventing cancer. β-Carotene has a molecular formula of C₄₀H₅₆, and it contains two rings and no triple bonds. How many double bonds does it have?

Textbook Question

Give five examples of structures with this formula (C₆H₁₂). At least one should contain a ring, and at least one should contain a double bond.

Hint: If you prefer to use a formula, elements of unsaturation = 1/2(2C + 2 - H)

C = number of carbons

H = number of hydrogens

Textbook Question

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

a. C₄H₄Cl₂

b. C₄H₈O

c. C₆H₈O₂

Textbook Question

For each of the following molecular formulas, determine the number of elements of unsaturation, and draw three examples.

d. C₅H₅NO₂

e. C₆H₃NClBr

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Determine the degree of unsaturation for hydrocarbons with the following molecular formulas:c. C12H20d. C40H56

Key Concepts

Degree of Unsaturation

Hydrocarbon Structure

Molecular Formula Interpretation

Watch next

Determine the degree of unsaturation for hydrocarbons with the following molecular formulas:
c. C₁₂H₂₀
d. C₄₀H₅₆