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The definition of a buffer in chemistry is a solution that can resist pH change when an acid or base is added. It’s made up of a weak acid and its conjugate base, or the other way around.
In acid-base chemistry, a buffer is a very useful solution. When a strong acid or base is added to a solution, the pH can vary quickly and significantly.
A buffer solution serves to neutralise part of the added acid or base, allowing for a more gradual shift in pH. This is accomplished by incorporating components that will react with hydrogen or hydroxide ions, preventing them from having a significant impact on pH.
Buffer solutions have a limit to how much they can neutralise; after this buffer has reached its capacity, the solution will behave as if there is no buffer present, and the pH will begin to fluctuate rapidly again.
Buffers make it easy to analyse and experiment with strong acids and bases. A real-world application of buffers is the bicarbonate buffering system, which is used to regulate blood pH.
Components of a Buffer Solution
A buffer must contain one of two choices: a weak acid and its conjugate base or a weak base and its conjugate acid. The way that the components are chosen have to do with the desired pH of the solution.
Acidic Buffer
An acidic buffer has a pH of less than 7; these solutions are made with a weak acid and its conjugate base as a salt. If you want to change the pH of the solution, you can change the ratio between the acid and salt. Additionally, different acids (along with their conjugate salts) can affect the pH in different ways.
Acetic acid and sodium acetate is an example of a weak acid and its conjugate salt. The acid equilibrium is going left; however, if you add sodium acetate, acetate ions are added into solution. Due to Le Chatelier’s Principle, the equilibrium will then switch to the left.
Acid in an Acidic Buffer
What would happen if acid was introduced to the above-mentioned example buffer? To remove the hydrogen ions from the entering acid, the buffer must work.
Acetic acid will be formed when the acetate ions mix with the hydrogen ions. Because acetic acid is a weak acid, the process can remove hydrogen ions faster than the acetic acid can dissociate, hence the pH does not change significantly.
Acidic Buffer: Adding Base
Let’s return to the buffer solution from earlier. It’s a little more difficult to add a base to communicate with this buffer.
The acetic acid will react with the hydroxide ion from the base, forming acetate ions and water; because the hydroxide ions are removed, the pH will not rise. In addition, additional hydrogen ions from acetic acid dissociation can interact with the hydroxide to generate water. Most of the hydroxide ions interact with hydrogen ions in these procedures to remove the basic presence, but not enough to significantly modify the pH.
Basic (Alkaline) Buffer Example of a Basic (Alkaline) Buffer
A basic buffer is a solution with a pH greater than 7 that is formed from a weak base and its conjugate acid in the form of a salt. To begin, the amounts of both components should be identical; however, you can modify the pH of the solution by changing the ratio of base to acidic salt, just as you can with acidic buffers.
Ammonia and ammonium chloride are two weak bases that have the same conjugate acid. The equilibrium is shifting to the left, but if you add ammonium chloride, you’ll get ammonium ions in the solution. The equilibrium will drift even more to the left this time, thanks to Le Chatelier’s Principles.
H2O(l) + NH3(aq) ⇋ NH4+(aq) + OH– (aq)
Acid in the Basic Buffer
Let’s look at what would happen if acid was introduced to the example buffer from earlier. The additional acid’s hydrogen will react with the ammonia to generate ammonium ions.
Many hydrogen ions will be removed as a result of this. Due to the reaction between ammonia and water, there are some hydroxide ions in the solution; these hydroxide ions will mix with the acidic hydrogens to generate additional water. These procedures will eliminate the majority of hydrogen ions, removing the acidic presence and helping to buffer the pH change.
Adding a Base Buffer to the Basic Buffer
What if you added base to the buffer solution from the top? To remove the hydroxide ions from the entering base, the buffer must work. The hydroxide ions will react with the ammonium ions in the solution.
The process can be reversed when ammonia reacts with water since it is a weak base, although not all of the hydroxide ions will be removed from solution. The pH will not alter significantly as a result of this.
Conclusion
The definition of a buffer in chemistry is a solution that can resist pH change when an acid or base is added. It’s made up of a weak acid and its conjugate base, or the other way around.
In acid-base chemistry, a buffer is a very useful solution. When a strong acid or base is added to a solution, the pH can vary quickly and significantly.
A buffer solution serves to neutralise part of the added acid or base, allowing for a more gradual shift in pH. This is accomplished by incorporating components that will react with hydrogen or hydroxide ions, preventing them from having a significant impact on pH.
