The alkanes are a homologous series of compounds containing only carbon and hydrogen that have the general formula . Members of this series include butane (), 2,2-dimethylpentane (), hexane (), and heptane (). The boiling points of some members of this homologous series are shown. Using their condensed structural formulas, match the compound with the most likely boiling point.
Rank from highest to lowest boiling point.
2,2-dimethylpentane () <---- Highest Boiling Point
heptane ()
hexane ()
butane () <---- Lowest Boiling Point
I believe heptane has the highest b.p. followed by 2,2-dimethylpentane, followed by hexane and butane.
In order from highest to lowest.
heptane, 2,2-dimethylpentane, hexane, and butane .
The boiling points of alkanes increase with increasing molecular weight and branching decreases the boiling point. So, the correct ranking from the highest to lowest boiling point for the given compounds is as follows:
1. 2,2-dimethylpentane () - Highest Boiling Point
2. heptane ()
3. hexane ()
4. butane () - Lowest Boiling Point
To determine the boiling points of the given compounds, we need to consider the molecular structure and molecular weight of each compound. Boiling points are influenced by factors such as molecular size and intermolecular forces.
In this case, all the compounds are alkanes, which have a single bond between carbon atoms and only contain carbon and hydrogen. The boiling points of alkanes increase with increasing molecular weight. Therefore, the compound with the highest molecular weight will have the highest boiling point.
Let's examine the molecular structures and molecular weights of the compounds:
- Butane (): The molecular structure of butane consists of 4 carbon atoms in a straight chain. Its molecular weight is 58 g/mol.
- 2,2-Dimethylpentane (): The molecular structure of 2,2-dimethylpentane contains a chain of 5 carbon atoms with two methyl groups attached to the second carbon. Its molecular weight is 114 g/mol.
- Hexane (): Hexane consists of a straight chain of 6 carbon atoms. Its molecular weight is 86 g/mol.
- Heptane (): The molecular structure of heptane contains a chain of 7 carbon atoms. Its molecular weight is 100 g/mol.
Based on molecular weight, we can rank the compounds from lowest to highest:
1. Butane (): Molecular weight = 58 g/mol
2. Hexane (): Molecular weight = 86 g/mol
3. Heptane (): Molecular weight = 100 g/mol
4. 2,2-Dimethylpentane (): Molecular weight = 114 g/mol
Therefore, the compound with the highest boiling point is 2,2-dimethylpentane (), and the compound with the lowest boiling point is butane ().