Question

What is a buffer solution? How is it prepared? Explain the buffer action of a basic buffer action with a suitable example.

Answer 1

In-general when we say buffer it means something which reduces shock, which acts as a resistance, which generates a moderate impact. In the same way, a chemical buffer is a solution whose $pH$ remains unchanged.

Complete step by step answer:
Buffer is a solution whose acidity or alkalinity remains unchanged or after adding acid or base it resists the $pH$value is called a buffer solution. It maintains the hydrogen ion concentration.
It is prepared by adding acid or base depending upon which kind of acidic or basic buffer we need to form. By using Henderson equation we can explain preparation of acid or basic buffer
For acid buffer: let us consider weak acid $HA$and salt $KA$ with a strong base $KOH$ reacting with each other. Ionization of $HA$ takes place.
$HA + {H_2}O \rightleftharpoons {H^ + } + {A^ - }$
Acid dissociation constant=$Ka = \dfrac{{\left[ {{H^ + }} \right]\left[ {{A^ - }} \right]}}{{HA}}$, taking negative log on both sides:
$- \log Ka = - \log \left[ {{H^ + }} \right] - \log \left( {\dfrac{{\left[ {{A^ - }} \right]}}{{\left[ {HA} \right]}}} \right)$
$pH$ of acid buffer is
$pOH = pKa - \log \left( {\dfrac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}} \right)$ $pH = pKa - \log \left( {\dfrac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}} \right)$
Similarly,$pH$ of basic buffer for weak base $B$ and its salt $BA$ with strong acid is
$pOH = pKb - \log \left( {\dfrac{{\left[ {salt} \right]}}{{\left[ {acid} \right]}}} \right)$
Basic acid is a mixture of weak acid and it conjugate base
For example, Add hydroxide ions with ammonium ions in the buffer, it reacts with ammonia to form water and ammonia. Therefore $pH$value does not change a lot.
$N{H_4}^ + + O{H^ - } \to N{H_3} + {H_2}O$

Note: Buffer solution is used in pharmaceutical industries at a large scale, it is also used in fermentation and food industry as well as dye industries. It has a wide range of applications. Bicarbonate buffering system is used for regulating the $pH$ of blood.