1.1: Unbranched Alkanes
- Naming Unbranched Alkanes (Organic Chemistry)
An alkane is a type of hydrocarbon (a compound consisting of only carbon and hydrogen atoms). When the carbon-carbon backbone consists only of single bonds, the hydrocarbon contains as many hydrogen atoms as possible, and is therefore saturated . Alkanes are saturated hydrocarbons.
Below is a table of the names of unbranched, saturated alkanes containing up to ten carbons, with their condensed structural formulas, molecular formulas, and boiling points.
| Alkane | Condensed Structural Formula | Molecular Formula | Boiling Point (degrees C) |
|---|---|---|---|
| Methane | CH 4 | CH 4 | -161 |
| Ethane | CH 3 CH 3 | C 2 H 6 | -89 |
| Propane | CH 3 CH 2 CH 3 | C 3 H 8 | -42 |
| Butane | CH 3 CH 2 CH 2 CH 3 | -0.5 | |
| Pentane | CH 3 (CH 2 ) 3 CH 3 | 36 | |
| Hexane | CH 3 (CH 2 ) 4 CH 3 | 69 | |
| Heptane | 98 | ||
| Octane | 126 | ||
| Nonane | 151 | ||
| Decane | 174 |
Table of names, condensed structural formulas, molecular formulas, and boiling points of unbranched saturated alkanes containing up to ten carbon atoms.
- Fill in the blank spaces in the table.
- Draw the structures of these ten unbranched alkanes, using Figure \(\PageIndex{1}\) (hexane) as a model.
- What do the names of these molecules have in common?
- What is the relationship between the number of carbon atoms and the number of hydrogen atoms in an unbranched alkane? Provide a general formula (use n for the number of carbon atoms).
- Draw a graph of boiling points versus number of carbon atoms in unbranched alkanes.
- How do the boiling points vary with the number of carbons? Propose an explanation for this observation.