From Big Medical Encyclopedia

CAUSTIC SODA (sodium hydroxide, sodium hydrate, the caustic soda, NaOH) — the crystal substance having properties of strong alkali; affects fabrics in a cauterizing way, dissolving proteins with formation of alkaline albuminates. At permanent job with E. N often arise dermatitis (see), eczema (see) and other skin diseases.

E. the N represents crystals of white color, t ° pl 320 °, t ° kip 1390 °, density at 20 ° 2,13 g/cm 3 . On air blurs, absorbing water vapors, and also carbon dioxide gas, interacting about the Crimea, E. the N gradually turns into sodium carbonate (Na 2 CO 3 ). Therefore E. N store in bottletight vessels. E. we will well dissolve N in water: at 20 ° in 100 ml of water 109 g E are dissolved. N, at 100 ° — 342 g, at 0 ° — 42 g; dissolution E. the N in water is followed by considerable calorification and almost full dissociation of substance on ions: NaOH -> Na + + IT - . It is well dissolved also in ethanol, methanol, glycerin and it is insoluble on air. E. the N is applied in aluminum production (an alkaline way of receiving alumina), in production of synthetic fiber, in soap-producing production, in paper, oil refinery and coal industry, by production of phenol, resorcin, naphthalene, alizarine, indigotin and so forth E. the N is a part of antiscale agent (structure for cleaning of coppers of a scum).

By the main method of receiving E. the N is electrolysis of water solution of sodium chloride. Except electrolysis, E. N receive also boiling of soda with hydrated lime: Na 2 CO 3 + Ca(OH) 2 -> CaCO 3 + 2NaOH.

E. the N reacts with to-tami and acid oxides with formation of the corresponding sodium salts. With solutions of salts of many metals E. the N forms the corresponding bases.

The solutions and pieces which got on skin and mucous membranes E. N strongly corrode them (see. Burns ). Hit E is especially dangerous. the N in eyes since at the same time are surprised not only superficial, but also deeper layers of an eye (e.g., an iris of the eye), can be a consequence of what a blindness. At permanent job with solutions E. N often arise various chronic damages of skin.

Impact on skin of hands of solutions E. the N in the conditions of high temperature leads to the state known under the name of «a hand of laundresses». Nails at working with E. N become brittle, fragile, burst at edges and separate from a nail bed.

First aid

At hit on skin E. N recommend washing of an affected area a water jet within 10 min., then a lotion from 5% of solution acetic, tartaric or lemon to - t. At hit E. the N in eyes needs immediate careful washing of eyes a water jet or fiziol. solution within 10 — 30 min.; then it is necessary to dig in eyes 2% solution of novocaine or 0,5% solution of Dicainum.

Washing should be made several times a day.

Maximum allowable concentration for an aerosol E. N of 0,5 mg/m 3 .

Measures of the prevention: goggles, rubber gloves and aprons, mechanization and sealing of the corresponding productions.

See also Acids and bases , Alkalis .

Bibliography: Harmful substances in the industry, under the editorship of N. V. Lazarev, the p. 2, page 338, L., 1971; Of e of N and N L. S. and Kovalyov H. M. Modern production of chlorine and the caustic soda, M., 1960; Remy G. Kurs of inorganic chemistry, the lane with it., t. 1, page 186, M., 1972.

V. P. Mishin.