What is a Buffer?
A buffer is a solution containing either a weak acid and its conjugate base pair or a weak base and its conjugate acid pair, which is resistant to changes in pH.
An interactive animation of pH buffers:
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/buffer12.swf
How does a Buffer work?
When a pH buffer reacts with an acid, molecules in the buffer attach to the floating hydrogen (H+) ions in the acid. This is because the H+ ions are what the foundation of the acid in the solution. Therefore, removing of these ions by the buffer reduces the strength of the acidity in the solution. This is also known as neutralization.
Similarly, when a pH buffer reacts with a base, molecules in the buffer bind to the loose hydroxide (OH–) ions in the acid. OH– is the foundation of the basic solution. Therefore, removing these ions by the buffer make the solution less basic.
An example of this would be:
A buffer made of a weak acid plus its conjugate base pair, or weak base plus its conjugate acid pair.
For example, a weak acid is added (Acetic Acid) HCH3COO– ↔ H+ + CH3COO. To make a buffer knowing the acid and conjugate base, you take equal amounts of the weak acid + the same concentration of a conjuagate base, in this case NaCH2COO–. Add the acid and conjuage base (salt) together and mix it with H2O. This solution creates a buffer solution. It can resist any change in pH.
When a strong acid is added (HCl à H+ + Cl–).
When adding HCl, H+ ions are added as well. These H+ ions will react with the acetate ions to from acetic acid. Most of the H+ is disloved in the reaction, making sure extra H+ won’t be floating around the solution. Therefore the buffer has worked, and the solution is neutralized.
When a strong Base is added (NaOH à Na+ + OH–):
The hydroxide ions (OH) would increase, therefore disturbing the homoeostasis in the buffer system. However, OH+ + HCH2COO à H2O + CH2COO– . Therefore, most of the OH+ is used in the reaction, causing the solution to remain at a balanced homoeostasis.
This can be summerized by this video:
pH Buffer in Blood/ Le Châtelier’s Principle:
Carbonic acid (H2CO3) is the acid and water is the base. The conjugate base for H2CO3 is HCO3– hydrogen carbonate ions. Carbonic acid also detaches quickly to generate water and carbon dioxide, as shown in the equilibrium.
Le Châtelier’s Principle can be used to describe how the kidneys help avoid excessively high pH (alkalosis). When the pH of the blood is too high, the kidneys eliminate hydrogen carbonate ions (HCO3–) from the blood by neutralizations. As the kidneys decrease the blood’s concentration of HCO3–, the equilibrium reaction is shifted toward the left to balance for the loss in HCO3–, according to Le Châtelier’s Principle. When the equilibrium shifts to the left, more H+ ions are generated together with HCO3– ions. As a result, the pH decreases.
– http://www.chemistry.wustl.edu/~edudev/LabTutorials/Buffer/Buffer.html
The pH in my blood changes…SO WHAT?
The normal pH of blood is 7.4. The pH of human blood has to stay in a narrow range of 7.4. Anything above 7.8 or below 6.8 can result in death. If the pH rises slightly over 7.4, it is known as acidosis, and anything below 7.4 is known as alkalosis.
The pH of blood changes because of many different factors. Acidosis can be caused by large, unneeded quantities of acidic substances in the blood. This happens due to, physically pushing your body to an extreme state, diabetes, or over eating. The bodys’ natural response is heavy breathing to reduce CO2 in the blood. Alkalosis can be caused by hyperventilation, which can significantly reduce the amount of carbonic acid. This also happens because the basic substances (medications) are taken in excessive quantities.
What is the purpose and importance of a blood buffer?
Blood buffers work all around the body to aid in maintaining the pH of blood (7.4). The buffers eliminate acids (carbonic acid) and bases (Hydrogen Carbonate ions). Changes in these concentrations can affect the entire body within seconds. The most common symptoms are increased/decreased breathing. Changes in hydrogen carbonate ions usually require hours to have any effect, however slowly they do induce damage. However mostly all acid is released through the kidneys, through urine.
References
http://www.chemistry.wustl.edu/~edudev/LabTutorials/Buffer/Buffer.html
http://www.youtube.com/watch?v=l9dliAngF2k
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/buffer12.swf
Grade 12U Chemistry-Systems and Equilibrium 
Well done! I do have a question, you talk about the body’s natural response to an increase in acidity (heavy breathing), but what does your body do in order to combat alkalosis?
Well alkalosis is caused by the pH being on the basic side of the pH scale (obviously). To prevent alkalosis you can make sure that your kidneys and liver are healthy. Your kidneys and livers dispose of your bodys’ waste. You can keep them healthy by eating the right foods (the 5 food groups) and making sure your body is properly nourished so H+, and CO is being produced constantly.
Great job!!. I like the information you have presented in this blog and also the format. But I have a question.What controls the blood pH and what happens when it gets too low or too high? Also what helps you maintain the blood pH in your body?
Thank you 🙂 . The buffer system is that control the blood pH, so depending on the situation H+, or OH- is added/removed. Two main forces at work on a daily basis that can disrupt the pH of your blood – these forces are the acid or alkaline. This happens because of foods and liquids that you ingest, and the acids that you generate through regular metabolic activities. So it really comes down to eating right, and keeping your body healthy.