Question

What is the conjugate for benzoic acid, $\left( {H{C_7}{H_5}{0_2}} \right)$ $?$

Answer 1

Here we have to know what is conjugate for acids. Then conjugate-based is obtained by removing one hydrogen atom from a given acid.

Complete step by step answer:
A conjugate acid contains one more $H$ atom and one more positive charge than the base that formed it. A conjugate base contains one less $H$ atom and one more negative charge, than the acid that formed it is Conjugate Base. Hence, conjugate base is a substance formed when an acid loses a hydrogen ion. Considered a base because it can gain a hydrogen ion to reform the acid. The weakest acid has the strongest conjugate base. Similarly, the strongest acid has the weakest conjugate base. Examples are chloride ion(weakest) is a conjugate base for hydrochloric acid (strongest) and hydrogen sulphate ion(weakest) is a conjugate base for sulphuric acid (strongest).
The formula of the conjugate base is the formula of the acid less one hydrogen. The reacting base becomes its conjugate acid. The formula of the conjugate acid is the formula of the base plus one hydrogen ion. Then by the definition of conjugate of acid, we get the below formula
${C_6}{H_5}COOH \to {C_6}{H_5}CO{O^ - } + {H^ + }$
The conjugate base of benzoic acid (${C_6}{H_5}COOH$) is benzoate (${C_6}{H_5}CO{O^ - }$).

Note:
Note that, to determine whether a substance is an acid or a base, count the hydrogens on each substance before and after the reaction. If the number of hydrogens has decreased that substance is the acid (donates hydrogen ions). If the number of hydrogens has increased that substance is the base (accepts hydrogen ions).