Buffers and How They Work

When calculating the pH of solutions, you can see that only a small amount of a strong acid is required to substantially affect the pH.

 However, for some investigations, maintaining a somewhat constant pH when acids or bases are introduced to the solution either by reaction or by the experimenter is desired. 

Buffers are intended to fulfill this function. 

Buffers are commonly used by chemists to keep the pH of a reaction under check. Buffers have a wide range of applications in biology, from maintaining blood pH to ensuring that urine does not become excruciatingly acidic.

Simply put, a buffer is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. Buffers control the pH by reacting with any added acid or base. 

Consider the operation of a buffer consisting of the weak base ammonia (NH3) and its conjugate acid, NH4+. When HCl is introduced to the buffer, the NH3 “soaks up” the proton of the acid, resulting in NH4+. Because the proton is bound to the ammonium ion, it does not contribute much to the solution’s pH increase. The ammonium ion transfers a proton to the base when NaOH is added to the same buffer, resulting in ammonia and water. In this case, the buffer also acts as a base neutralizer.

A buffer operates by substituting a strong acid or base with a weak one, as seen in the example above. The proton of the strong acid is replaced by the weak acid ammonium ion.

 The weak base ammonia was used in place of the strong base OH-. Buffers’ amazing ability to control pH is due to the substitution of weak acids and bases for stronger ones.

Buffer solutions are divided into two categories

buffer that is acidic

The pH of acid buffer solutions is less than 7. It’s usually created with a weak acid and one of its salts (often referred to as conjugate*).

 Acidic buffer solutions are commonly employed and consist of a solution of ethanoic acid and sodium ethanoate, which have a pH of 4.76 when mixed in equal molar amounts. The pH of the buffer solution can be altered by altering the acid-to-salt ratio or by using a different acid and one of its salts.

a buffer of alkaline

A weak base and one of its salts are used to make alkaline buffer solutions, which have a pH greater than 7. A blend of ammonia and ammonium chloride solution is a common example of an alkaline buffer solution. The pH of the solution would be 9.25 if these were blended in equal molar amounts.

What are buffers and how do they work?

Buffers work by neutralising any added acid (H+ ions) or base (OH- ions) to keep the pH at a stable level, effectively making them a weaker acid or base. Consider a buffer composed of the weak base ammonia (NH3) and its conjugate acid, NH4+. 

The extra H+ ions introduced to the system are consumed by the NH3 to create NH4+ when HCl (strong acid) is added to the buffer system. The pH of the system does not change considerably because all of the excess H+ ions have been locked up and have created a weaker acid, NH4+. When NaOH (strong base) is added to this buffer system, the ammonium ion contributes a proton to the base, resulting in ammonia and water, neutralising the base without changing the pH much.

Breaking of the buffer solution is a term that describes what happens when the entire base and its conjugate acid (in this case, NH3 and NH4+) are consumed to neutralise the added acid or base. 

The pH of the buffer will swiftly alter if an acid or base is added to it. Thus, the buffer’s capacity, or the quantity of acid or base a buffer can absorb before breaking its capacity, is its breaking point. It’s worth noting that a weak base solution has a higher buffer capacity for adding a strong acid, whereas a weak acid solution has a higher buffer capacity for adding a strong base.

Conclusion

The pH of acid buffer solutions is less than 7. It’s usually created with a weak acid and one of its salts (often referred to as conjugate*).

Buffers work by neutralising any added acid (H+ ions) or base (OH- ions) to keep the pH at a stable level, effectively making them a weaker acid or base. Consider a buffer composed of the weak base ammonia (NH3) and its conjugate acid, NH4+. 

The weak base ammonia was used in place of the strong base OH-. Buffers’ amazing ability to control pH is due to the substitution of weak acids and bases for stronger ones.