Buffer

The buffer solution is a substance that resist changes in pH when small amounts of acid or base added to them. Acidic buffer solution is something that has pH less than 7. Acidic buffer solution typically made of a weak acid and garammya, frequently sodium salt. Common examples are a mixture of sodium ethanoate and ethanoic acid in solution. In this case, if the solution containing an equal molar concentration of acid and salt, then the mixture will have a pH of 4.76. This is not a problem in terms of concentration, as long as both have the same concentration.

You can change the pH of the buffer by changing the ratio of acid to salt, or by selecting a different acid and one of the salts. The alkaline buffer solution has a pH above 7. The alkaline buffer solution is usually made from a weak base and its salts. Often used as an example is a mixture of ammonia and ammonium chloride solution. If both are in a state of comparable molar ratio, pH of the solution will have a 9:25. Once again, it's not a problem for the concentration you select both the same.

Buffer solution containing something that will remove hydrogen ions or hydroxide ions which you might add - on the contrary will change the pH. Buffer solution of the acidic and alkaline achieve this condition in a different manner. We will take a mixture of sodium ethanoate and ethanoic acid as a typical example of the acidic buffer solution. Ethanoic acid is a weak acid, and the position of equilibrium will be shifted to the left:

Addition of sodium ethanoate in these conditions add to the excess ethanoate ions in significant amounts. Based on Le Chatelier's Principle, the end of the next equilibrium position shifted toward the left.

Therefore, the solution will contain something important:

• Many of ethanoic acid is not ionized;

• Much of the sodium ethanoate ethanoate ions:

• enough hydrogen ions to make the solution become acidic.

Something else (such as water and sodium ions) that are not important in the explanation.

Addition of acid in the acidic buffer solution should eliminate most of the new hydrogen ion opposite pH ill drop by once conspicuous. Of hydrogen ions join ethanoate ion to produce ethanoic acid. Although the reaction is reversible, for ethanoic acid is a weak acid, a large part of the new hydrogen ions is removed through this method.

Since most of the new hydrogen ions is removed, the pH will not change too much - but because the equilibrium involved, the pH will be slightly decreased. Addition of base in the acidic buffer solution

Aqueous solution containing a buffer solution of hydroxide ions and hydroxide ions remove them.

This time the situation is slightly more complicated because there are two processes that can eliminate the hydroxide ions. Removal of hydroxide ions by reaction with acid ethanoate. Most of the acidic substances which hydroxide ions collide with molecules of ethanoic acid. Both will be reacted to form the ethanoate ions and water.

Because most of the hydroxide ion is eliminated, the pH does not change too much. Removal of hydroxide ions by reaction with hydrogen ions. It must be remembered that some of the existing hydrogen ions from ionization aetanoat acid.

Hydroxide ions can be joined to form water. As long as that happens, replace the tip equilibrium. This still happens to most of the hydrogen ion is removed.

Once again, because you have a balance involved, not all of the hydroxide ion is removed - because there are too many. Ionized water formed back into a very small tingat to give some hydrogen ions and hydroxide ion.

The alkaline buffer solution

We will menganbil mixture of ammonia and ammonium chloride as a typical example.

Ammonia is a weak base, and the position of equilibrium will move to the left:

Addition of ammonium chloride was added on condition of excess ammonium ions within a large number. Based on Le Chatelier's Principle, it will cause the tip equilibrium position will shift to the left.

Therefore, the solution will contain a few important things:

• Many of ammonia does not react;

• Many of ammonia from ammonium chloride ion;

• Enough hydrogen ions to produce the alkaline solution.

Other things (like water and chloride ions) are not important in the explanation.

Addition of acid to alkaline buffer solutions

There are two processes that can remove hydrogen ions that you add.

Removal of hydrogen ions by reaction with ammonia is

Most of the basic substance which hydrogen ions collide with a molecule of ammonia. Both will react to form ammonium ions.

Most, but not all, hydrogen ions are omitted. Acidic ammonium ion is a little weak, and therefore will be released back hidrohen ions.

Removal of hydrogen ions through the reaction with hydroxide ions

It must be remembered that the existing beberepa hydroxide ions derived from the reaction between ammonia and water.

Hydrogen ions can react with hydroxide ions to produce water. As long as that happens, replace the end of the hydroxide ion equilibrium. This continues to happen until the majority of hydrogen ions is removed.

Once again, because you have a balance involved, not all the hydrogen ions is removed - just mostly.

Addition of bases in the alkaline buffer solution

Hydroxide ions of alkali removed melali simple reaction with ammonium ions.

Because the ammonia formed is a weak base, ammonia will react with water - and therefore less reversible reaction. This means that, once again, most (but not all of them) hydrogen ions removed from solution.

source : www.chem-is-try.org