Question

The following equilibrium exists in aqueous solution \[C{H_3}COOH \rightleftharpoons C{H_3}CO{O^ - }\; + {\text{ }}{H^ + }\]
If dilute \[HCl\]is added:
A. Acetate ion concentration will decrease
B. The equilibrium constant will increase
C. The equilibrium constant will decrease
D. Acetate ion concentration will increase

Answer 1

Hint: Weak electrolytes can dissociate in a solvent upto a specific quantity. Acetic acid is a weak acid. One weak electrolyte dissociates into ions partially, the number of ions per unit volume of the weak electrolyte helps in determining the solubility of that electrolyte.

Complete step-by-step answer:In order to know that when the solute is mixed with water, the result is an aqueous solution. For instance, \[NaCl\] solution in water is an aqueous solution.
When a material or chemical in solution releases hydrogen ions \[({H^ + })\], then they are known as acids. All hydrogen ions \[({H^ + })\] and chloride ions \[(C{l^ - })\] produce when a strong acid, hydrochloric acid \[(HCl)\] dissociates and are no longer bound together by ionic bonds.
If a strong acid or a strong base is added then the pH value of the solution will drastically change. For instance, the reaction \[C{H_3}COOH \rightleftharpoons C{H_3}CO{O^ - }\; + {\text{ }}{H^ + }\] occurs in reverse direction when a strong acid like \[HCl\] is added to solution.

Lechatelier's principle states when a system is subjected to the change in a concentration, temperature, volume or pressure then it changes to the new equilibrium and this transition has partially cancels out the applied change.
Therefore, according to Lechatelier's principle, equilibrium will shift backward if diluted \[HCl\] is introduced because it will increase the concentration of \[{H^ + }\] ions. Then, the concentration of acetate ions will drop.

Option ‘A’ is correct

Note: It should be noted that in water, hydrogen chloride is totally ionises into hydrogen and chloride ions. As a result of \[HCl\]'s potent acidity, its conjugate base \[(C{l^ - })\] is incredibly weak. The chloride ion is unable to combine with the \[{H^ + }\] ion to form HCl once more. That means, the conjugate base of a stronger acid is weaker.