What is the function of a buffer

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Buffer solutions

Numerous reactions take place in the metabolism in which -ions are released or consumed. On the other hand, a constant value in the cytoplasm or in certain body fluids such as the blood is vital. Even slight deviations lead to serious symptoms, major changes lead to death. Metabolism-related "shocks" must therefore be buffered. Various buffer systems in the blood fulfill this function.

In general, solutions whose value changes only slightly when acid or base are added are called buffer solutions. They contain a conjugated acid-base pair, the acid ions neutralizing the base ions. Buffer solutions can be prepared by

  • weak acids with their salt (e.g. the acetate buffer made from acetic acid and sodium acetate) or
  • mixes weak bases with their salt (e.g. the ammonium buffer made from ammonium chloride and ammonia).

If both species are present in sufficiently high concentrations, the acetate buffer reacts as follows:

Buffering the addition of strong acids:

The added strong acid reacts completely. The fact that the value nevertheless changes slightly has to do with the effect - already discussed during the neutralization - that the acetic acid formed can in turn dissociate (to a small extent).

Buffering the addition of strong bases:

The buffer effect is shown in the titration curve of weak acids and bases by the plateau in the area of ​​the value, i.e. it is the reason for the slight increase in the titration curve for acetic acid at 4 to 6.