Question

Which out of the following is $$C{H}_{3}CO{O}^{-}$$ ion?
A.Weak conjugate base
B.Strong conjugate base
C.Weak conjugate acid
D.Strong conjugate acid

Answer 1

Hint: According to the Bronsted-Lowry protonic concept, acids are chemical compounds that are proton donors whereas bases are chemical compounds that are proton acceptors. The chemical compounds that behave as an acid or a base can be a molecule, a cation, or an anion.

Complete answer:
Step 1
According to Bronsted-Lowry, an acid-base reaction can be represented as
                                                 $$Acid$$ ->$$Base$$ $$+$$ $$H^{+}$$
Thus, we can say that acid and a base are related to each other. Every acid gets converted into a base after releasing a proton, and every base changes into acid after accepting a proton. So, all the acids and bases exist in pairs which are known as conjugate pairs. Therefore, the conjugate is a term for a chemical compound that differs from the other only due to a difference in the number of protons.
Step 2
According to this concept, neutralization is the process of transfer of a proton from the acid to its conjugate base.
Step 3
The acidic strength of an acid is determined by its tendency to lose a proton. Greater is the tendency of the acid to lose a proton, the stronger is the acid.
Step 4
The basic strength of a base is determined by its tendency to gain a proton. Greater is the tendency of the base to gain a proton, stronger is the base.
Step 5
The conjugate of a strong acid is always a weak base whereas the conjugate of a weak acid is always a strong base.
Step 6
Acetic acid is a weak acid which dissociates in water as follows:
                                       $$C{H}_{3}COOH$$$$+$$$$H_{2}O$$->$$C{H}_{3}CO{O}^{-}$$$$+$$$$H_3{O}^{+}$$
The equilibrium constant for acetic acid in the given reaction is $$K_a={\displaystyle \frac{[C{H}_{3}CO{O}^{-}][H_{3}O]}{[C{H}_{3}COOH]}}=1.8\times {10}^{-5}$$.
The equilibrium constant for the acetate ion would be $$K_{eq}={\displaystyle \frac{1}{K_a}}={\displaystyle \frac{[C{H}_{3}COOH]}{[C{H}_{3}CO{O}^{-}][H_{3}O]}}=5.5\times {10}^4$$.
So, we can find that the conjugate base of a weak acid has a higher dissociation constant value so is a strong base.
Thus, we can see that acetate ion $$C{H}_{3}CO{O}^{-}$$, the conjugate base of the weak acid, acetic acid $$C{H}_{3}COOH$$ is a strong base.

Hence, the correct option for the given question is option b).

Note:As per the Arrhenius concept an acid is a substance that gives $$H^{+}$$ ion in aqueous solution while a base furnishes $$O{H}^{-}$$ ions in aqueous solution.