Definition of Buffer Solution
A buffer is a solution containing either a weak acid and its salt or a weak base and its salt, which is resistant to changes in pH. To put it simply, a buffer is an aqueous solution of either a weak acid and its conjugate base or a weak base and its conjugate acid.
A buffer might also be called a pH buffer, hydrogen ion buffer, or buffer solution. The Henderson-Hasselbalch equation may be used to gauge the approximate pH of a buffer. In order to use the equation, the preliminary concentration or stoichiometric concentration is gotten in instead of the equilibrium concentration.
The basic form of a buffer chemical reaction is:
HA ⇌ H+ + A −
Types of Buffer Solution
Acid buffer solutions have a pH of less than 7. It is generally made from a weak acid and among its salts (frequently called conjugate *). Typically utilized acidic buffer solutions are a mix of ethanoic acid and salt ethanoate in solution, which have a pH of 4.76 when mixed in equal molar concentrations. You can change the pH of the buffer solution by altering the ratio of acid to salt, or by picking a different acid and among its salts.
Alkaline buffer solutions have a pH greater than 7 and are made from a weak base and one of its salts. Avery commonly used the example of an alkaline buffer solution is a mixture of ammonia and ammonium chloride solution. If these were mixed in equivalent molar proportions, the solution would have a pH of 9.25.
Working of Buffer Solution
Let’s take the example of a solution of acetic acid (CH3COOH) and salt acetate (CH3COONa). Here, acetic acid is weakly ionized while sodium acetate is almost completely ionized. The formulas are offered as follows:
CH3COOH H+ + CH3COO–
CH3COONa Na+ + CH3COC–
To this, if you add a drop of a strong acid like HCl, the H+ ions from HCl combine with CH3COO– to offer feebly ionized CH3COOH. Thus, there is a really small modification in the pH value. Now, if you add a drop of NaOH, the OH– ions react with the complimentary acid to provide undissociated water particles.
CH3COOH + OH– CH3COO– + H2O
In this way, the OH– ions of NaOH are eliminated and the pH is practically unchanged.
Preparing a Buffer Solution
There are a couple of ways to prepare a buffer solution of a specific pH. In the very first approach, prepare a solution with acid and its conjugate base by dissolving the acid kind of the buffer in about 60% of the volume of water required to get the final solution volume. Then, measure the pH of the solution utilizing a pH probe. The pH can be changed approximately to the preferred value using a strong base like NaOH.
If the buffer is made with a base and its conjugate acid, the pH can be changed using a strong acid like HCl. As soon as the pH is appropriate, water down the solution to the last preferred volume.
Alternatively, you can prepare solutions of both the acid form and base form of the solution. Both solutions must include the exact same buffer concentration as the concentration of the buffer in the final solution. To get the final buffer, add one solution to the other while monitoring the pH.
Significance of Buffer Solution
- Buffer solutions are utilized for comparing calorimetrically the hydrogen ion concentration of unknown solutions.
- Acetic acid-sodium acetate is used in the removal of phosphate radical throughout the qualitative analysis of the solution.
- Buffer is utilized for the precipitation of hydroxides of the third group of qualitative analysis.
- Bicarbonate Buffer
The maintenance of blood pH is controlled by means of the bicarbonate buffer. This system includes carbonic acid and bicarbonate ions. When the blood pH drops into the acidic range, this buffer acts to form carbon dioxide gas. The lungs expel this gas out of the body during the procedure of respiration. During alkaline conditions, this buffer brings pH back to neutral by triggering excretion of the bicarbonate ions through the urine.
- The respiratory pigment present in blood, hemoglobin, likewise has buffering action within tissues. It has the ability to bind with either protons or oxygen at a given point in time. Binding of one release the other. At the time of workout or exercise, protons are generated in excess. Hemoglobin helps in the buffering action by binding these protons, and at the same time releasing molecular oxygen.
- In industries, buffer solutions are used in alcoholic fermentation (pH 5 to 6.5), tanning of leather, electroplating, manufacture of sugar, paper manufacturing, and so on.