Buffer solution or called buffer is one type of electrolyte solution that is very important in life. Have you ever imagined how the human body maintains its pH remained neutral, because when the pH of human blood increases or decreases dramatically it will cause death.
The human body applies a buffer system as a solution to maintain blood pH at neutral conditions. Therefore this buffer solution is very beneficial for life. In this article we will discuss the definition of a buffer solution, the Buffer System in the Body, the formula and calculation of the pH in the buffer solution, and examples.
table of contents
- Buffer Solution
- Type of Buffer Solution
- Acid Buffer
- Base Buffer
- Buffer Solution Calculation Formulas
- Acid Buffer Solution
- Base Buffer Solution
- The pH buffer system in the human body
- Examples of Questions and Methods of Resolution
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- Type of Buffer Solution
A buffer solution is a solution containing weak acids and their conjugate bases or weak bases and conjugated acids that are resistant to pH changes. In other words, a buffer is a solution that is able to maintain the pH condition of a solution.
When a solution experiences acid or base addition, the pH will change drastically, but in the presence of this buffer solution adding acid or base to the solution will only slightly change the pH of the solution and the change is not significant.
Therefore this buffer solution is widely used as a solution to maintain a solution so that it has a pH that tends to remain with various chemical treatments.
But in its application, the selection of a buffer solution to maintain the pH of the solution is based on the pH range that can be neutralized by the solution itself. The pH range is the maximum amount of acid or base that can be added to the solution before changing the pH or called the buffer capacity.
A buffer solution can maintain the pH of the solution or is resistant to changes in pH due to an equilibrium between the acid (HA) and its conjugate base (A – ). The equation that describes it is as follows:
⇌ HA H + + A –
When strong acid is added, H + will increase in the equilibrium system so that it will shift to the left in accordance with Le Chatelier’s principles. This causes the concentration of H + to increase. Likewise, if a strong base is added, the concentration of hydrogen H + ions will decrease so that the equilibrium will shift to the right.
Type of Buffer Solution
In general, a buffer solution or buffer is divided into two kinds, namely acid buffer and base buffer.
As the name implies, acid buffer is a buffer that is added to maintain the acidic atmosphere in a solution. This acid buffer has a pH below 7 which at that pH is the acidic pH. An acid buffer can be formed from a mixture of a weak acid solution with its conjugated base salt or it can also be formed from a mixture of excess weak acid with other strong bases.
Examples of acid buffer solution of weak acid mixture with salt conjugate base is a solution of CH 3 COOH which is coupled with a weak acid and CH 3 COONa which is a conjugate base salts which can produce ions CH 3 COO – .
CH 3 COOH (aq) ⇌ CH 3 COO – (aq) + H + (aq)
An example of an acid buffer from a mixture of weak acids with a strong base is an excess of CH 3 COOH solution mixed with a strong base of NaOH so that it will produce a conjugated base salt.
CH 3 COOH (aq) + NaOH (aq) ⇌ CH 3 COONa (aq) + H 2 O (l)
If the acid buffer is able to maintain the acid solution, the base buffer is the opposite where the base buffer is the solution that is able to maintain the pH of the solution which is alkaline. This base buffer can be formed from a mixture of excess weak base solution with its conjugated acid salt or from a mixture of weak base with strong acid.
Examples of base buffers that are formed from a mixture of weak bases with conjugate acid salts are a mixture of NH 3 which is a weak base and NH 4 Cl which is a conjugated acid salt of NH 3 .
NH 3 (aq) + H 2 O (l) ⇌ NH 4 + (aq) + OH – (aq)
Examples of base buffers from a mixture of weak bases with strong acids are a mixture of excess NH 3 solution which is a weak base with HNO 3 which is a strong acid so that it will form a conjugated acid salt from NH 3 .
NH 3 (aq) + HNO 3 (aq) ⇌ NH 4 NO 3 (aq)
Buffer Solution Calculation Formulas
As for the formulas commonly used in the calculation of a special organizing solution for its pH, they are as follows;
Acid Buffer Solution
In an acid buffer solution there is an equilibrium between acid and its conjugate base salt, for example:
CH 3 COOH ⇌ H + + CH 3 COO –
Based on the reaction equation, the value of Ka can be determined
Where Ka values are generally known and moles of weak acids and conjugate bases can also be determined.
If the value of [H + ] is known, the pH can be determined using the following formula:
pH = – log [H + ]
Base Buffer Solution
In the base buffer solution there is a balance between the weak base and the conjugate acid salt, for example:
NH 3 + H 2 O ⇌ NH 4 + + OH –
Based on the reaction equation, the value of Kb can be determined
Where Kb values are generally known and weak base moles and conjugate acids can also be determined.
If the value of [OH – ] is known, pOH can be determined using the following formula:
pOH = – log [OH – ]
While the pH value can be calculated with the following formula:
pH + pOH = 14
pH = 14 – pOH
The pH buffer system in the human body
As was mentioned earlier that the human body needs to maintain the pH of the blood to remain in neutral pH because when the pH of the blood increases or decreases dramatically it can cause death.
Therefore, in the human body, blood pH buffer has a very big role in maintaining human life. The human body uses a weak acid buffer, H 2 CO 3 carbonic acid with the conjugate base salt, HCO 3 – . This buffer system is able to maintain the pH of human blood in the range of 7.35-7.45 so it remains safe.
When there is a strong enough acid in the blood the H + from that acid will react with HCO 3 – or conjugate base salt through the meaning of a chemical reaction :
H ++ HCO 3 – ⇌ H 2 CO 3
But when our body has a high enough base, OH – from that base will react with H 2 CO 3 through the following reaction:
OH – + H 2 CO 3 ⇌ HCO 3 – + H 2 O
Through this buffer system, the pH in human blood can still survive near neutral conditions despite the presence of acidic and basic substances that enter the body.
Examples of Questions and Methods of Resolution
In order to clarify this buffer solution, the following are examples of questions and answers that can be given. Such as;