Acid-Base Equilibrium

(redirected from Acid-base reaction)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to Acid-base reaction: Redox reaction

acid-base equilibrium

[′as·əd ′bās ‚ik·wə′lib·rē·əm]
(chemistry)
The condition when acidic and basic ions in a solution exactly neutralize each other; that is, the pH is 7.

Acid-Base Equilibrium

 

the set of physicochemical and physiological processes making for the relative constancy of the pH of the internal medium of the organism.

The normal pH of human blood is kept to 7.35–7.47, despite the influx of acidic and basic products of metabolism. Constancy of the pH of the internal medium is a necessary condition for the normal occurrence of the life processes. Values of blood pH that go beyond the limits indicated are evidence of major disturbances in the organism. Values below 6.8 and above 7.8 are incompatible with life.

Numerous physiological systems participate in the maintenance of constant blood pH. In addition to these there are buffer systems, which consist of weak acids and their strong-base salts (for example, hemoglobin, which possesses the properties of a weak acid, and its salt, potassium carbonate; and carbonic acid, H2CO3, and its salt, sodium bicarbonate, NaHCO3).

The buffer-system mechanism of maintaining acid-base equilibrium can be demonstrated by the example of the cation of bicarbonate. If a strong acid, such as hydrochloric acid, enters the blood, it reacts with the bicarbonate to give the weak carbonic acid, which is almost without effect on the pH of the medium (NaHCO3 + HCL = NaCL + H2CO3). When a strong base enters the blood it reacts with the carbonic acid to give bicarbonate, which also has little effect on the pH. The capacity of the bicarbonate buffer should be rapidly exhausted by an accumulation of either carbonic acid or bicarbonates; this does not occur, however, thanks to the action of certain physiological systems, such as respiration and excretion, which restore the capacity of the buffer. Thus, when carbonic acid (carbon dioxide) accumulates, it is removed through the lungs, and excess bicarbonate is eliminated through the kidneys. A shift in blood pH in the acid direction is called acidosis; a shift in the alkaline direction is called alkalosis. The pH of the majority of tissue fluids is maintained at 7.1–7.4.

REFERENCE

Robinson, J. R. Osnovy reguliatsii kislotno-shchelochnogo ravnovesiia. Moscow, 1969. (Translated from English.)

V. P. MISHIN

References in periodicals archive ?
In compomer materials the acid- base reaction is initially limited because of the anhy- drous structure, but once water is absorbed then a belated acid-base reaction is likely to happen.19
After some historical introduction and a brief overview of the beer-making process, several chapters orient the reader to basic concepts of chemistry, special properties of water molecules and acid-base reactions, and selected strands of organic chemistry relevant to beer.
During the SPOCAS procedure, soils with excess acid neutralising capacity ([ANC.sub.E]) undergo three acid-base reactions. First during peroxide oxidation under heat, any pyrite oxidised to sulfuric acid is fully neutralised by ANC present in the sample.
Titrations range from very general chemical reactions such as acid-base reactions that are pH sensitive to highly specific chemistries that require ion specific electrodes.
The side chains may also have carboxyl (COOH), amino or imino (=NH) groups which can participate in acid-base reactions. In acidified solutions the carboxyl groups are neutral while the nitrogen-containing groups tend to be positively charged, and this class of fibre interacts strongly with acid dyes.
Some complex acid-base reactions ultimately determine the rate of plastic discoloration, as do the type of organic additives in the formulation and the presence of organic compatibilizers or silica or alumina coated onto the Ti[O.sub.2] pigment particles.

Full browser ?