Question

1) 2-hexanol boils at 140deg C and 2-pentanol boils at 120 deg C. account for the different boiling points.

2) 2-pentanol boils at 120 deg C and its constitutional isomer ethyl propyl ether boils at 55 deg C.account for the different boiling points.

Answer 1

1)

Both 2-hexanol and 2-pentanol are having same functionality (such as hydroxy) and both can able to undergo hydrogen bonding. If both compounds are having similar properties and functionalities, then molecular masses will play a vital role to dictate the outcome of boiling point. Molecular mass increases then boiling point increases.

2-hexanol is having greater molecular mass compared to the 2-pentanol. Hence, 2-hexanol will show greater boiling point value compared to the 2-pentanol

2)

However, both 2-pentanol and ethyl propyl ether are constitutional isomers. The functional group present in both are different. One is alcohol another one is ether.

Alcohol can have ability show hydrogen bonding but ether will not. So, 2-pentanol will show greater boiling point compared to the ether (ethyl propyl ether).