Which of the following compounds has the highest boiling point

Which of the following compounds has the highest boiling point? CH4, CH3CH2CH2CH2OH CH3SOCH3, CH3CH2CH2CH2OH CH3OCH2CH(CH3)2 CH3CH2OCH2CH2CH3 Which of the following compounds should be the most water soluble? OH CH3

The Correct Answer and Explanation is:

Part 1: Compound with the Highest Boiling Point

Compounds given:

1. CH₄ (Methane)
2. CH₃CH₂CH₂CH₂OH (Butanol)
3. CH₃SOCH₃ (Dimethyl sulfoxide)
4. CH₃CH₂CH₂CH₂OH (Repeated – same as 2)
5. CH₃OCH₂CH(CH₃)₂ (Ether with branching)
6. CH₃CH₂OCH₂CH₂CH₃ (Another ether)

Correct Answer: CH₃CH₂CH₂CH₂OH (Butanol)

Explanation:

Boiling point depends on intermolecular forces. The stronger the forces, the more energy is needed to separate the molecules, and the higher the boiling point.

• CH₄ has only London dispersion forces. It is nonpolar and has the lowest boiling point.
• CH₃CH₂CH₂CH₂OH (butanol) is a straight-chain alcohol and exhibits strong hydrogen bonding, dipole-dipole forces, and London forces.
• CH₃SOCH₃ (dimethyl sulfoxide or DMSO) has strong dipole-dipole interactions due to the highly polar S=O bond but does not form hydrogen bonds as strong as those in alcohols.
• CH₃OCH₂CH(CH₃)₂ and CH₃CH₂OCH₂CH₂CH₃ are ethers. Ethers cannot hydrogen bond to themselves and thus have weaker intermolecular forces than alcohols.
• Therefore, CH₃CH₂CH₂CH₂OH has the highest boiling point due to strong hydrogen bonding and a relatively larger surface area.

Part 2: Most Water-Soluble Compound

Given:
A compound with –OH and CH₃ groups

Correct Answer: The compound with an –OH (hydroxyl) group

Explanation:

Water solubility depends on a molecule’s ability to hydrogen bond with water. The –OH group is highly polar and can form strong hydrogen bonds with water, making such compounds highly water soluble.

• A CH₃ group is nonpolar and hydrophobic. It does not hydrogen bond well with water and thus contributes little to solubility.
• A molecule like methanol (CH₃OH) is water soluble due to the presence of the hydroxyl group.
• Therefore, among choices with either OH or CH₃, the one with –OH is significantly more water soluble.