Natriumhydroxid substansmängd

Toxics Screening Level

The Initial Threshold Screening Level (ITSL) for sodium hydroxide is 8 μg/m3 with a 1-hour averaging time. It is used to neutralize acids; tomake sodium salts; to precipitate metals astheir hydroxides; in petroleum refining; in thesaponification of esters; in the treatment ofcellulose, plastics, and rubber; and in numeroussynthetic and analytical applications.

Commercially, caustic soda is available in anhydrous form, but in most mining applications the caustic soda is supplied as a 50% solution.
In the mineral processing industry, sodium hydroxide is mostly used for alkalinity control during the processing of non-metallic minerals.

Uses

Sodium hydroxide (NaOH) is one of the most useful industrial sodium compounds. Caustic soda is a very active substance and is highly corrosive.

Uses

sodium hydroxide is used to adjust a product pH to make it more acceptable to the skin. Sodium hydroxide can be purified by dissolving 100g in 1L of pure EtOH, filtering the solution under vacuum through a fine sintered-glass disc to remove insoluble carbonates and halides.

Hot and/or concentrated NaOH can cause hydroquinone to decompose exothermically at elevated temperature. The previous ITSL established on 9/14/1992 was 20 μg/m3 (1-hour averaging time). Sodium hypochlorite (NaOCl) is used extensively for cleaning and as a disinfectant.Common household bleach consists of about 5% sodium hypochlorite solution. The first is known as the brine cell or the primary electrolyzer in which sodium ion deposits on the mercury cathode forming amalgam, while chlorine gas is liberated at the anode:
Na⁺ + Cl^–→ Na-Hg (cathode) + ½Cl₂(g) (anode)
In the second cell, known as the decomposer cell, a graphite cathode is used while sodium amalgam serves as the anode.

Reacts with great violence with phosphorus pentaoxide when initiated by local heating [Mellor 8 Supp.3:406 1971]. The oral lethal dosein rabbits is 500 mg/kg (NIOSH 1986).
Sodium hydroxide dusts or aerosols areirritating to the eyes, nose, and throat. In base metal flotation, the use of sodium hydroxide is rare. it also functions to neutralize acids in various food products.

For example, sodium amalgam is prepared by the electrolysis of 3L of 30% NaOH with 500mL of pure mercury for cathode, and a platinum anode, passing 15 Faradays at 4Amps, in a thick-walled polyethylene bottle. Sodium hydroxide is a minor ingredient in many commonhousehold products, but in a few it may constitute more than half of the product.

Heating with a mixture of methyl alcohol and trichlorobenzene during an attempted synthesis led to a sudden increase in pressure and an explosion [MCA Guide for Safety Appendix 3 1972]. It is used to control pH and neutralize acids in chemical processes. Chlorine gas is liberated at the anode and sodium ion at the cathode. NaOH and KOH generate considerable heat when dissolved in water; when mixing with water, always add caustics slowly to the water and stir continuously.

Carbonate ion can be removed by passage through an anion-exchange column (such as Amberlite IRA-400; OH--form). The column should be freshly prepared from the chloride form by slow prior passage of sodium hydroxide solution until the effluent gives no test for chloride ions. Its solubility in water is 111% by weight and a vapor pressure of 0mmHg (NIOSH, 1994).
It can react with tricholoethylene (TCE) to form flammable dichloroacetylene and with metals to form hydrogen gas (OEHHA, 1993).