1. Some questions on Physical properties of alkanes
Chem-160
4/3/2019

2. Arrange the alkanes in each set in order of increasing boiling point
Arrange the alkanes in each set in order of increasing boiling point. (a) Butane, decane, and hexane (b) 2-Methylheptane, octane, and 2,2,4-trimethylpentane All of these compounds are unbranched alkanes. As the number of carbon atoms in the chain increases, dispersion forces between molecules increase, as does the amount of energy required to put the molecules into motion. Therefore, the larger the unbranched alkane, the higher are the boiling points. Decane has the highest boiling point, and butane has the lowest
Chem-160
4/3/2019

3. Trimethylpentane (bp 99°C), 2-Methylheptane (bp 118°C), Octane, (bp 126°C)
These three alkanes are constitutional isomers with molecular formula C8H18. Their relative boiling points depend on the degree of branching.
2,2,4-Trimethylpentane, the most highly branched isomer, has the smallest surface area and the lowest boiling point. Octane, the unbranched isomer, has
the largest surface area and the highest boiling point.
Chem-160
4/3/2019

4. Questions
Arrange the alkanes in each set in order of increasing boiling point.
(a) 2-Methylbutane, 2,2-dimethylpropane, and pentane
(b) 3,3-Dimethylheptane, 2,2,4-trimethylhexane, and nonane
Chem-160
4/3/2019