Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

The acidic or basic properties of a substance in aqueous solution are related to its ability to donate or accept protons (H⁺ ions). Let’s look at the examples you mentioned:

1. Hydrochloric Acid (HCl):

» In aqueous solution, HCl dissociates into H⁺ ions and Cl⁻ ions.

» HCl → H+ + Cl⁻
» The presence of H⁺ ions in solution makes it acidic.

2. Nitric Acid (HNO₃):

» In aqueous solution, HNO₃ dissociates into H⁺ ions and NO₃⁻ ions.
» HNO₃ → H+ + NO₃⁻
» Again, the presence of H⁺ ions in solution makes it acidic.

Substances like alcohols (e.g., ethanol) and glucose do not exhibit acidic behavior in aqueous solution. This is because they do not readily release protons (H⁺ ions) into the solution. For example, ethanol does undergo partial ionization in water, but it doesn’t release as many H⁺ ions as strong acids do:

C₂H₅OH ⇌ C₂H₅O⁻ + H⁺

However, the extent of ionization for alcohols and glucose is much lower compared to strong acids like HCl or HNO₃. As a result, the concentration of H⁺ ions in the solution is not high enough to cause a significant change in pH, and the solution is not classified as acidic.