BICARBONATES (sovr. name hydrocarbonates) — acid salts coal to - you are H 2 CO 3 ; some of them in an organism take part in maintenance of constancy of pH of blood. General formula of MHCO 3 , where M — monovalent metal. B. easily rastvorima in water. Less others we will dissolve sodium bicarbonate (in 100 g of water at t ° 0 6,5 g are dissolved, at t ° 20 ° — 8,8 g, at t ° 50 ° - 12,6 g). At B.'s heating carbon dioxides and waters decay with formation of carbonates: 2NaHCO 3 = Na 2 CO 3 + CO 2 + H 2 O. Acids force out carbon dioxide from B.: NaHCO 3 + HCl = NaCl + CO 2 + H 2 O. Aqueous solutions of B. owing to hydrolysis have alkalescent reaction:
HCO 3 - + H 2 O ⇆ H 2 CO 3 + OH -
(at t ° 20 ° NaHCO solution 3 it is poorly painted by phenolphthalein, apprx. 0 ° hydrolysis decreases and solution becomes colourless). At boiling balance of hydrolysis is displaced to the right, and coal to - that decays with allocation of CO 2 .
Ca calcium bicarbonate (HCO 3 ) 2 and Mg magnesium bicarbonate is more rare (HCO 3 ) 2 , dissolved in natural waters, cause carbonate, or temporary, water hardness, edges can be eliminated with boiling. B. at the same time collapse with formation of the insoluble carbonates which are dropping out in a deposit: Ca (HCO 3 ) 2 = CaCO 3 + CO 2 + H 2 O.
Ion HCO - 3 along with ions of Cl - , SO 4 2- , Na + , K + , Ca 2+ , Mg 2+ enters into group of the main ions of waters of mineral sources (see. Mineralnye Vody ). The huge role is played by B. of sodium and potassium which form with coal to - that the bicarbonate buffer participating in maintenance of constancy of pH of blood (see. Buffer systems , Acid-base equilibrium ).
Broad application in medical practice is found by sodium bicarbonate (Natrium bicarbonicum — NaHCO 3 — bicarbonate, or drinking, soda). It is applied inside in powders, tablets and solutions at a hyperoxemia of a gastric juice, a peptic ulcer of a stomach and duodenum. Solutions of sodium bicarbonate apply to rinsings, washings and inhalations.
See also Carbonic acid .
Bibliography: Mashkovsky M. D. Pharmaceuticals, p. 2, page 191, M., 1972; Nekrasov B. V. Fundamentals of the general chemistry, t. 2, M., 1967; Remy G. Kurs of inorganic chemistry, the lane with it., t. 1, M., 1972.
E. A. Maksimyuk.