Which of the following substances will have hydrogen bonds between molecules

Which of the following substances will have hydrogen bonds between molecules? CH3NH2 CH3-O-CH3 CH3CH2OH CH3CH2F Both CH3CH2F and CH3CH2OH

The Correct Answer and Explanation is:

The correct answer is CH3NH2 (methylamine) and CH3CH2OH (ethanol).

Explanation:

Hydrogen bonding occurs when hydrogen is bonded to a highly electronegative atom like fluorine (F), oxygen (O), or nitrogen (N), and this hydrogen is attracted to a lone pair of electrons on another electronegative atom in a neighboring molecule.

1. CH3NH2 (Methylamine):
   • Methylamine consists of a nitrogen (N) atom bonded to two hydrogen atoms (NH2) and a methyl group (CH3). The nitrogen is highly electronegative and has a lone pair of electrons. The hydrogen atoms attached to nitrogen can form hydrogen bonds with the lone pair of electrons on the nitrogen of neighboring molecules. Therefore, methylamine will form hydrogen bonds.
2. CH3-O-CH3 (Dimethyl ether):
   • In dimethyl ether, the oxygen atom is bonded to two methyl groups (CH3). Although oxygen is electronegative and can form hydrogen bonds, there are no hydrogen atoms directly bonded to the oxygen. Therefore, dimethyl ether will not form hydrogen bonds since the hydrogen atoms are not attached to highly electronegative atoms like oxygen, nitrogen, or fluorine.
3. CH3CH2OH (Ethanol):
   • Ethanol contains a hydroxyl group (-OH), where the oxygen atom is bonded to a hydrogen atom. The oxygen is electronegative and can form hydrogen bonds with the hydrogen atoms in other ethanol molecules. Thus, ethanol will form hydrogen bonds.
4. CH3CH2F (Ethyl fluoride):
   • Ethyl fluoride has a fluorine atom bonded to a two-carbon chain. Fluorine is highly electronegative and can form hydrogen bonds. However, in this case, there is no hydrogen atom bonded to fluorine or oxygen or nitrogen, so ethyl fluoride does not form hydrogen bonds in the same way as the other molecules.

Therefore, CH3NH2 and CH3CH2OH will exhibit hydrogen bonding due to the presence of hydrogen atoms bonded to highly electronegative atoms (nitrogen and oxygen).