Textbook Question
Based on the molecular formula, determine whether each compound is an alkane, alkene, or alkyne. (Assume that the hydrocarbons are noncyclical and there is no more than one multiple bond.) a. C5H12 b. C3H6 c. C7H12 d. C11H22
Ch.21 - Organic Chemistry
Chapter 21, Problem 34
Based on the molecular formula, determine whether each com- pound is an alkane, alkene, or alkyne. (Assume that the hydro- carbons are noncyclical and there is no more than one multiple bond.)
a. C8H16 b. C4H6 c. C7H16 d. C2H2
Verified step by step guidance1
Determine the general formula for alkanes, which is C_nH_{2n+2}.
Determine the general formula for alkenes, which is C_nH_{2n}.
Determine the general formula for alkynes, which is C_nH_{2n-2}.
For each compound, compare its molecular formula to the general formulas for alkanes, alkenes, and alkynes.
Classify each compound based on which general formula it matches.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Hydrocarbon Classification
Hydrocarbons are organic compounds consisting solely of hydrogen and carbon. They are classified into three main categories: alkanes (single bonds), alkenes (at least one double bond), and alkynes (at least one triple bond). Understanding the type of bonds present in a hydrocarbon is essential for determining its classification.
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General Formula for Hydrocarbons
Each class of hydrocarbons has a general formula that helps identify their structure. Alkanes follow the formula CnH2n+2, alkenes follow CnH2n, and alkynes follow CnH2n-2. By comparing the molecular formula of a compound to these general formulas, one can ascertain whether it is an alkane, alkene, or alkyne.
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Degree of Unsaturation
The degree of unsaturation indicates the number of rings and multiple bonds in a hydrocarbon. It can be calculated using the formula: Degree of Unsaturation = (2C + 2 + N - H - X)/2, where C is the number of carbons, N is the number of nitrogens, H is the number of hydrogens, and X is the number of halogens. A higher degree of unsaturation suggests the presence of double or triple bonds, which is crucial for classifying the compound.
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