Question

Which of the following is used as a differentiating solvent for acids?
A) ${\text{C}}{{\text{H}}_3}{\text{COOH}}$
B) ${{\text{H}}_2}{\text{O}}$
C) ${\text{HCl}}{{\text{O}}_4}$
D) None of these

Answer 1

Hint: The weak bases act as the differentiating solvents for acids as the acid can be differentiated due to the base’s leveling effect. Acetic acid is a weak base.
Step-by-Step Explanation: The solvent is the liquid in which a substance (solute) is easily dissolved to form a solution. The strength of strong acid is limited or leveled by the use of a basic solvent due to its basicity. When a strong acid is dissolved in a weakly basic solvent like acetic acid it exhibits more acidic properties than acetic acid as acetic acid has poor proton accepting character. Here, Acetic acid is used as a differentiating solvent for acids as the stronger acids are only slightly dissociated in acetic acid. Since acetic acid has less tendency to accept the proton donated, the strong acid only slightly dissociates. The reaction of acid HA with acetic acid will give an acid and a base ion. The reaction is as follows-
$ \Rightarrow {\text{HA + C}}{{\text{H}}_3}{\text{COOH}} \rightleftharpoons \left( {{\text{C}}{{\text{H}}_3}{\text{COOH}}_2^ + } \right) + {{\text{A}}^ - }$
Here if the acid HA is strong then the reaction will not lie very much to the right side of the equilibrium because the acetic acid (acts as a basic solvent) is poor acceptor of proton so the dissociated ${{\text{H}}^ + }$ ion will again form acid from which it was dissociated. Thus strong acid only slightly dissociates whereas weak acids completely dissociate. So the acids dissociate to different degrees in basic solvent which helps in differentiating the acids.

Hence, the correct answer is ‘A’.

Note: The weak bases act as differentiating solvent for acids. Similarly strong bases act as leveling solvent for acids as strong bases have greater affinity for protons so all acids become indistinguishable in strength when dissolved in strongly basic solvent. This effect of base is called leveling effect. As the strong base has a very high affinity for proton so even the strong acids will completely dissociate in it so the strength of strong and weak acids cannot be differentiated.