Sodium hydroxide, or caustic soda is an inorganic compound that belongs to the class of bases, or hydroxides. Also in technology and abroad, this substance is called caustic soda. The trivial name - caustic soda - it received because of its strong corrosive effect.
This is a white crystalline solid substance with hygroscopicity, melting at a temperature of 328 degrees. Sodium hydroxide is highly soluble in water and is a strong electrolyte. Upon dissociation, it decomposes into a metal cation and hydroxide ions.
When dissolved in water forms an active substance - alkali, - soapy to the touch. This reaction proceeds very rapidly - with spraying and heat. It is the ingress of alkali on the skin and mucous membranes that causes severe chemical burns, so when working, you must be careful and protect your hands and eyes. If this substance gets on the epithelium or in the eyes, mouth, it is necessary to rinse the affected area as quickly as possible with water and a weak solution of acetic (2%) or boric (3%) acid, and then again with water. After providing emergency care, the victim must be shown to the doctor.
Sodium hydroxide (the formula of the chemical compound is NaOH, the structural one is Na-OH) is a chemically active substance that can react with both inorganic and organic substances. A qualitative reaction to hydroxide-ion with various indicators will help to detect it in aqueous solutions. So, the litmus indicator turns dark blue, the orange-orange - yellow, and phenolphthalein - raspberry, while the color intensity will depend on the concentration of alkali.
Sodium hydroxide enters into such reactions:
1. neutralization with acids, acid oxides and amphoteric compounds. The result of this reaction is the formation of water and salt or a hydroxocomplex - in the case of interaction with amphoteric bases and oxides;
2. exchange with salts;
3. with metals that are up to hydrogen in the Beketov series and have a low electrochemical potential;
4. with non-metals and halogens;
4. hydrolysis with ethers;
5. saponification with fats (soap and glycerin are formed);
6. interactions with alcohols (substances formed alcoholates).
Also, in molten form, caustic soda can destroy porcelain and glass, and with the access of oxygen - a noble metal (platinum).
Sodium hydroxide can be obtained in the following ways:
- electrolysis of an aqueous solution of NaCl (diaphragm and membrane method),
- chemical (calcareous and ferritic method).
In recent years, methods based on electrolysis have been most often used, since they are more profitable.
Caustic soda is very popular and is used in many industries - cosmetic, pulp and paper, chemical, textile, food. It is used as an additive E-524, for the degassing of rooms and upon receipt of biodiesel.
Thus, sodium hydroxide is an alkali that has been widely used in various fields of human economic activity due to its chemically active nature.