Question

How do chemical buffer systems resist changes in pH?

Answer 1

Hint: You must first know that what is a buffer solution, the buffer solution is the solution added to any solution by which the solution resists the change in pH if any acidic solution or basic solution is added externally.

Complete step by step answer:
The buffer solution is a solution formed by the mixing of weak acid and its conjugate base or weak base and its conjugate acid where water is used as the solvent for the preparation of the buffer solution. The buffer solution resists the change in pH in addition to solvent or any other chemical compound.
The two main types of buffer are acidic buffer and alkaline buffer.
In acidic buffers the pH is less than 7 as it is acidic in nature. It is formed by mixing weak acid and its salt with a strong base. Example of acidic buffer: equal concentration of acetic acid and sodium acetate. The pH of the acidic buffer is 4.74.
In an alkaline buffer, the pH is more than 7 as it is basic in nature. It is prepared by mixing a weak base and its salt with strong acid. Example of alkaline buffer: aqueous solution prepared by equal concentration of ammonium hydroxide and ammonium chloride. The pH of the alkaline buffer is 9.25.
How the buffer solution resists the change in pH when added to another solution is shown by the mechanism given below.
In solution, as salt is ionic in nature it dissolves and completely breaks down to release its ions but weak acid partially breaks down to give its ion.
The dissociation is shown below.
$C{H_3}COONa \rightleftharpoons N{a^ + } + C{H_3}CO{O^ - }$
$C{H_3}COOH \to {H^ + } + C{H_3}CO{O^ - }$
On adding acid, the protons released by the acid will be removed by the acetate ion released by the acetic acid.
${H^ + } + C{H_3}CO{O^ - } \rightleftharpoons C{H_3}COOH(from\;buffer\;solution)$
On adding base, the hydroxide ion released by the base is removed by the hydrogen ion and as a result water is formed.
$H{O^ - } + {H^ + } \rightleftharpoons {H_2}O(from\;buffer\;solution)$
As a result, the pH of the solution will be maintained.

Note:
Buffer solution is used during performing titration where it is added in a small amount in the solution, as a result the solution does not change its pH. One of the applications of buffer solution is Buffer that is used in laundry detergents to prevent their natural ingredients from breaking down.