Question

Why do HCl, \[\text{HN}{{\text{O}}_{\text{3}}}\]etc., show acidic character in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Answer 1

Hint: Solve this question by applying the basics of properties and strength of acids. An acid is a substance or compound which can donate a proton. Strength of an acid depends on the ability of the compound to donate, when a compound can donate a proton easily, it is a strong acid.

Complete step by step answer:
An aqueous solution means a solution in which the solvent is water. Water is a polar compound which can dissociate as a proton and hydroxyl ion, i.e. –
\[{{\text{H}}_{\text{2}}}\text{O}\rightleftharpoons {{\text{H}}^{\text{+}}}\text{+O}{{\text{H}}^{\text{-}}}\]
Hydrochloric acid - HCl and nitric acid -\[\text{HN}{{\text{O}}_{\text{3}}}\] are strong acids in nature. It is because they dissociate completely as ions in aqueous solution. The reaction can be presented as –
\[\text{HCl}\to \text{ }{{\text{H}}^{\text{+}}}\text{+ C}{{\text{l}}^{\text{-}}}\]
\[\text{HN}{{\text{O}}_{\text{3}}}\to \text{ }{{\text{H}}^{\text{+}}}\text{+ NO}_{3}^{-}\]
Both hydrochloric and nitric acid increase the number of protons in the solution.
\[{{\text{H}}^{\text{+}}}\text{+ }{{\text{H}}_{\text{2}}}\text{O}\to {{\text{H}}_{\text{3}}}{{\text{O}}^{\text{+}}}\]
Therefore, we can say that it shows acidic character in aqueous solutions.
On the other hand, compounds like glucose \[\text{(}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{12}}}{{\text{O}}_{\text{6}}})\] and alcohol (ROH) do not ionize or dissociate in water to give proton \[\text{(}{{\text{H}}^{\text{+}}})\]. Hydrogen does not separate as an individual ion. Therefore, it does not show acidic character.

Additional Information:
Glucose is a carbohydrate and a component of sucrose. It exists as a six membered ring. It is also known by names such as blood sugar, corn sugar, grape sugar, etc. The structure of D-glucose is given below –

Note: Dissociation constant of strong acids is equal to one, it is because it dissociates completely, as we can see in the case of hydrochloric acid and nitric acid. Whereas, dissociation constant of strong acids is less than one, it is because weak acids do not dissociate completely. All organic acids are weak acids.