Question

Given a solution of acetic acid. How many times of the acid concentration, acetate salt should be added to obtain a solution with pH $7$?
${K_a}$ for dissociation of $C{H_3}COOH = 1.8 \times {10^{ - 5}}$ .

Answer 1

Equilibrium is any state in a reaction, in which the rate of formation of products from the reactants is equal to the rate of formation of reactants from the products. The rate of formation of product or the reactant is governed by a set of laws named as the Le- Chatelier’s Principle, given by Le- Chatelier and Braun from France in $1884$ .

Complete answer: pH is defined as the degree of measurement of the acidic or the alkali in a solution or a substance. Or in simple terms, pH is the negative logarithm of the hydrogen ion. Whereas pOH is defined as the degree of measurement of the basicity in a solution or a substance. Or in simple words, pOH is the negative logarithm of the hydroxide ion. pKa is the negative logarithm of the dissociation constant of an acid and pKb is the negative logarithm of the dissociation constant of a base.
$pH = p{K_a} + \log \dfrac{{[Salt]}}{{[Acid]}}$
Now putting the name of acid and salt we get,
$pH = p{K_a} + \log \dfrac{{[Acetate]}}{{[Acetic\,acid]}}$
Substituting the given values,
$7 = 5 - \log (1.8) + \log \dfrac{{[Acetate]}}{{[Acetic\,acid]}}$
Putting the value of $\log (1.8)$ i.e., $0.2552$ then,
$7 = 4.75 + \log \dfrac{{[Acetate]}}{{[Acetic\,acid]}}$
On rearranging,
$2.25 = \log \dfrac{{[Acetate]}}{{[Acetic\,acid]}}$
Taking antilog both sides
$179.9 = \dfrac{{[Acetate]}}{{[Acetic\,acid]}}$

Note:
The characteristics of equilibrium are as follows: -
(i) is a measurable quantity,
(ii) for the formation or the initiation of the equilibrium, the system should be closed,
(iii) is dynamics in nature meaning if the equilibrium is started, then it will continue and will never stop only condition is that the system is closed.