Question

Which is NOT a physical property of alcohols or phenols?
A. Phenols are generally only slightly soluble in water.
B. The hydroxyl group of an alcohol is nonpolar.
C. The solubilities of normal primary alcohols in water decrease with increasing molecular weight.
D. Boiling points of normal primary alcohols increase with increasing molecular weight.

Answer 1

Answer:

1. (a) phenols are generally only slightly soluble in water

Answer 2

Among the following, the one which is not a physical property of alcohols or phenols is B. The hydroxyl group of an alcohol is nonpolar.

Explanation:

• Alcohols are soluble in water due to the formation of hydrogen bonds while phenols are only slightly soluble in water due to the presence of a large hydrophobic phenyl group.
• The hydroxyl group of an alcohol is polar in nature, instead of nonpolar due to the electronegativity difference between oxygen and hydrogen atom.
• The solubilities of normal primary alcohols in water decrease with increasing molecular weight because the hydrophobic part increases with increasing molecular weight.
• Boiling points of normal primary alcohols increase with increasing molecular weight. This is also because of the increase of hydrophobic part with increasing molecular weight.