An aqueous solution of sodium hydroxide. Other properties of sodium hydroxide

Caustic soda is an alkali produced by electrolysis of a sodium chloride solution. Capable of corroding skin and leaving chemical burns. In everyday life there are other names for caustic soda: NaOH, sodium hydroxide, caustic, caustic alkali.

Caustic soda granules and crystals

The formula for sodium hydroxide is NaOH.

Atoms of sodium, oxygen and hydrogen.

Compound

The composition of caustic soda is white hard crystals. They look like sea salt and are easily soluble in water.

Caustic soda differs from baking soda: different properties, composition and formula. The alkaline environment of NaOH is 13 pH, while NaHCO 3 is only 8.5. In addition, baking soda is safe to use, unlike caustic soda.

Characteristics

Sodium hydroxide has the following characteristics:

Molar mass: 39.997 g/mol;
Crystallization (melting) temperature: 318°C;
Boiling point: 1388°C;
Density: 2.13 g/cm³.

Shelf life of caustic soda: 1 year, subject to storage conditions.

Solubility of caustic soda in water: 108.7 g/100 ml.

Caustic soda hazard class: 2 – highly hazardous substance. This is a dangerous cargo during transportation and requires compliance with safety standards: in solid form it is transported in special bags, in liquid form - in tanks.

Properties

Chemical and physical properties of sodium hydroxide:

Absorbs vapors from the air;
Gives abundant foam when dissolved in water and generates heat;
Reacts with acid and salts heavy metals, aluminum, zinc, titanium. Also interacts with acid oxides, non-metals, halogens, ethers, amides.

The French scientist A. L. Duhamel du Monceau first distinguished these substances: sodium hydroxide began to be called caustic soda, sodium carbonate - soda ash (from the Salsola Soda plant, from the ash of which it was extracted), and potassium carbonate - potash. Currently, soda is commonly called sodium salts carbonic acid. In English and French the word sodium means sodium, potassium - potassium.

Physical properties

Sodium hydroxide

Thermodynamics of solutions

Δ H 0 dissolution for an infinitely dilute aqueous solution is -44.45 kJ/mol.

From aqueous solutions at 12.3 - 61.8 °C, monohydrate crystallizes (orthorhombic syngonium), melting point 65.1 °C; density 1.829 g/cm³; ΔH 0 arr.−734.96 kJ/mol), in the range from -28 to -24°C - heptahydrate, from -24 to -17.7°C - pentahydrate, from -17.7 to -5.4°C - tetrahydrate ( α-modification), from -5.4 to 12.3 °C. Solubility in methanol 23.6 g/l (t=28 °C), in ethanol 14.7 g/l (t=28 °C). NaOH 3.5H 2 O (melting point 15.5 °C);

Chemical properties

(in general, such a reaction can be represented by a simple ionic equation; the reaction proceeds with the release of heat (exothermic reaction): OH - + H 3 O + → 2H 2 O.)

with amphoteric oxides that have both basic and acidic properties, and the ability to react with alkalis, as with solids during fusion:

ZnO + 2NaOH → Na 2 ZnO 2 + H 2 O

the same with solutions:

ZnO + 2NaOH (solution) + H 2 O → Na 2 (solution)+H2

(The anion formed is called tetrahydroxozincate ion, and the salt that can be isolated from the solution is called sodium tetrahydroxozincate. Sodium hydroxide also enters into similar reactions with other amphoteric oxides.)

with acid oxides - with the formation of salts; this property is used for cleaning industrial emissions from acid gases (for example: CO 2, SO 2 and H 2 S):

2Na + + 2OH - + Cu 2+ + SO 4 2- → Cu(OH) 2 ↓+ Na 2 SO 4

Sodium hydroxide is used to precipitate metal hydroxides. For example, this is how gel-like aluminum hydroxide is obtained by reacting sodium hydroxide with aluminum sulfate in an aqueous solution. It is used, in particular, to purify water from small suspended matter.

Hydrolysis of esters

with fats (saponification), this reaction is irreversible, since the resulting acid with alkali forms soap and glycerin. Glycerin is subsequently extracted from soap liquors by vacuum evaporation and additional distillation purification of the resulting products. This method of making soap has been known in the Middle East since the 7th century:

Saponification process of fats

As a result of the interaction of fats with sodium hydroxide, solid soaps are obtained (they are used to produce bar soap), and with potassium hydroxide, either solid or liquid soaps are obtained, depending on the composition of the fat.

HO-CH 2 -CH 2 OH + 2NaOH → NaO-CH 2 -CH 2 -ONa + 2H 2 O

2NaCl + 2H 2 O = H 2 + Cl 2 + 2NaOH,

Currently, caustic alkali and chlorine are produced by three electrochemical methods. Two of them are electrolysis with a solid asbestos or polymer cathode (diaphragm and membrane production methods), the third is electrolysis with a liquid cathode (mercury production method). Among the electrochemical production methods, the easiest and most convenient method is electrolysis with a mercury cathode, but this method causes significant harm environment as a result of evaporation and leakage of metallic mercury. Membrane method production is the most efficient, least energy-intensive and most environmentally friendly, but also the most capricious, in particular, it requires raw materials of higher purity.

Caustic alkalis obtained by electrolysis with a liquid mercury cathode are much cleaner than those obtained by the diaphragm method. This is important for some industries. Thus, in the production of artificial fibers, only caustic obtained by electrolysis with a liquid mercury cathode can be used. In world practice, all three methods for producing chlorine and caustic soda are used, with a clear tendency towards an increase in the share of membrane electrolysis. In Russia, approximately 35% of all caustic soda produced is produced by electrolysis with a mercury cathode and 65% by electrolysis with a solid cathode (diaphragm and membrane methods).

The efficiency of the production process is calculated not only by the yield of caustic soda, but also by the yield of chlorine and hydrogen obtained during electrolysis, the ratio of chlorine and sodium hydroxide at the output is 100/110, the reaction proceeds in the following ratios:

1.8 NaCl + 0.5 H 2 O + 2.8 MJ = 1.00 Cl 2 + 1.10 NaOH + 0.03 H 2,

Basic indicators various methods production is given in the table:

Indicator per 1 ton NaOH	Mercury method	Diaphragm method	Membrane method
Chlorine yield %	97	96	98,5
Electricity (kWh)	3 150	3 260	2 520
NaOH concentration	50	12	35
Chlorine purity	99,2	98	99,3
Hydrogen purity	99,9	99,9	99,9
Mass fraction of O 2 in chlorine, %	0,1	1-2	0,3
Mass fraction of Cl - in NaOH, %	0,003	1-1,2	0,005

Technological diagram of electrolysis with a solid cathode

Diaphragm method - The cavity of an electrolyzer with a solid cathode is divided by a porous partition - a diaphragm - into cathode and anode spaces, where the cathode and anode of the electrolyzer are respectively located. Therefore, such an electrolyzer is often called diaphragm, and the production method is diaphragm electrolysis. A flow of saturated anolyte continuously enters the anode space of the diaphragm electrolyzer. As a result of the electrochemical process, chlorine is released at the anode due to the decomposition of halite, and hydrogen is released at the cathode due to the decomposition of water. Chlorine and hydrogen are removed from the electrolyzer separately, without mixing:

2Cl - − 2 e= Cl 2 0 , H 2 O − 2 e− 1/2 O 2 = H 2 .

In this case, the near-cathode zone is enriched with sodium hydroxide. A solution from the near-cathode zone, called electrolytic liquor, containing undecomposed anolyte and sodium hydroxide, is continuously removed from the electrolyzer. At the next stage, the electrolytic lye is evaporated and the NaOH content in it is adjusted to 42-50% in accordance with the standard. Halite and sodium sulfate precipitate as the concentration of sodium hydroxide increases. The caustic alkali solution is decanted from the sediment and transferred as a finished product to a warehouse or to the evaporation stage to obtain a solid product, followed by melting, flaking or granulation. Crystalline halite (reverse salt) is returned to electrolysis, preparing the so-called reverse brine. To avoid the accumulation of sulfate in solutions, sulfate is removed from it before preparing the reverse brine. The loss of anolyte is compensated by adding fresh brine obtained by underground leaching of salt layers or by dissolving solid halite. Before mixing it with return brine, fresh brine is cleaned of mechanical suspensions and a significant part of calcium and magnesium ions. The resulting chlorine is separated from water vapor, compressed and supplied either for the production of chlorine-containing products or for liquefaction.

Membrane method - similar to the diaphragm, but the anode and cathode spaces are separated by a cation exchange membrane. Membrane electrolysis ensures the production of the purest caustic soda.

Technology system electrolysis

The main technological stage is electrolysis, the main apparatus is an electrolytic bath, which consists of an electrolyzer, a decomposer and a mercury pump, interconnected by communications. In the electrolytic bath, mercury circulates under the action of a mercury pump, passing through an electrolyzer and a decomposer. The cathode of the electrolyzer is a flow of mercury. Anodes - graphite or low-wear. Together with mercury, a stream of anolyte, a halite solution, continuously flows through the electrolyzer. As a result of the electrochemical decomposition of halite, Cl - ions are formed at the anode and chlorine is released:

2 Cl - - 2 e= Cl 2 0,

which is removed from the electrolyzer, and a weak solution of sodium in mercury, the so-called amalgam, is formed on the mercury cathode:

Na + + e = Na 0 nNa + + nHg - = Na + Hg

The amalgam continuously flows from the electrolyser to the decomposer. Water, well purified from impurities, is also continuously supplied to the decomposer. In it, sodium amalgam, as a result of a spontaneous electrochemical process, is almost completely decomposed by water with the formation of mercury, caustic solution and hydrogen:

Na + Hg + H 2 0 = NaOH + 1/2H 2 + Hg

The caustic solution obtained in this way, which is a commercial product, does not contain the admixture of halite, which is harmful in the production of viscose. The mercury is almost completely freed from the sodium amalgam and returned to the electrolyzer. Hydrogen is removed for purification. The anolyte leaving the electrolyzer is additionally saturated with fresh halite, the impurities introduced with it, as well as those washed out from the anodes and structural materials, are removed from it, and returned to electrolysis. Before saturation, the chlorine dissolved in it is removed from the anolyte in a two- or three-step process.

Laboratory methods of obtaining

Sodium hydroxide is produced in the laboratory by chemical means, which are more historical than practical.

Lime method The preparation of sodium hydroxide involves the interaction of a solution of soda with milk of lime at a temperature of about 80 °C. This process is called causticization; it is described by the reaction:

Na 2 C0 3 + Ca (OH) 2 = 2NaOH + CaC0 3

As a result of the reaction, a solution of sodium hydroxide and a precipitate of calcium carbonate are formed. The calcium carbonate is separated from the solution, which is evaporated to produce a molten product containing about 92% NaOH. Molten NaOH is poured into iron drums where it hardens.

Ferritic method described by two reactions:

Na 2 C0 3 + Fe 2 0 3 = Na 2 0 Fe 2 0 3 + C0 2 (1) Na 2 0 Fe 2 0 3 -f H 2 0 = 2 NaOH + Fe 2 O 3 (2)

(1) - the process of sintering soda ash with iron oxide at a temperature of 1100-1200°C. In this case, sodium speck ferrite is formed and carbon dioxide is released. Next, the cake is treated (leached) with water according to reaction (2); a solution of sodium hydroxide and a precipitate of Fe 2 O 3 are obtained, which, after separating it from the solution, is returned to the process. The solution contains about 400 g/l NaOH. It is evaporated to obtain a product containing about 92% NaOH.

Chemical methods for producing sodium hydroxide have significant disadvantages: it consumes a large number of fuel, the resulting caustic soda is contaminated with impurities, maintenance of the devices is labor-intensive. Currently, these methods are almost completely replaced by the electrochemical production method.

Caustic soda market

World production of sodium hydroxide, 2005

Manufacturer	Production volume, million tons	Share in world production
DOW	6.363	11.1
Occidental Chemical Company	2.552	4.4
Formosa Plastics	2.016	3.5
PPG	1.684	2.9
Bayer	1.507	2.6
Akzo Nobel	1.157	2.0
Tosoh	1.110	1.9
Arkema	1.049	1.8
Olin	0.970	1.7
Russia	1.290	2.24
China	9.138	15.88
Other	27.559	47,87
Total:	57,541	100

In Russia, according to GOST 2263-79, the following brands of caustic soda are produced:

TR - solid mercury (flake);

TD - solid diaphragm (fused);

PP - mercury solution;

РХ - chemical solution;

RD - diaphragm solution.

Indicator name	TR OKP 21 3211 0400	TD OKP 21 3212 0200	RR OKP 21 3211 0100	RH 1st grade OKP 21 3221 0530	RH 2nd grade OKP 21 3221 0540	RD Premium grade OKP 21 3212 0320	RD First grade OKP 21 3212 0330
Appearance	Flaky mass white. Light color allowed	White melted mass. Light color allowed	Colorless transparent liquid		Colorless or colored liquid. Crystallized sediment is allowed	Colorless or colored liquid. Crystallized sediment is allowed	Colorless or colored liquid. Crystallized sediment is allowed
Mass fraction of sodium hydroxide, %, not less	98,5	94,0	42,0	45,5	43,0	46,0	44,0

Indicators of the Russian liquid sodium hydroxide market in 2005-2006.

Business name	2005 thousand tons	2006 thousand tons	share in 2005%	share in 2006%
JSC "Kaustik", Sterlitamak	239	249	20	20
JSC "Kaustik", Volgograd	210	216	18	18
OJSC "Sayanskkhimplast"	129	111	11	9
LLC "Usolyekhimprom"	84	99	7	8
OJSC "Sibur-Neftekhim"	87	92	7	8
JSC "Khimprom", Cheboksary	82	92	7	8
VOJSC "Khimprom", Volgograd	87	90	7	7
CJSC "Ilimkhimprom"	70	84	6	7
OJSC "KCHKhK"	81	79	7	6
NAC "AZOT"	73	61	6	5
JSC "Khimprom", Kemerovo	42	44	4	4
Total:	1184	1217	100	100

Indicators of the Russian market of solid caustic soda in 2005-2006.

Business name	2005 tons	2006 tons	share in 2005%	share in 2006%
JSC "Kaustik", Volgograd	67504	63510	62	60
JSC "Kaustik", Sterlitamak	34105	34761	31	33
OJSC "Sibur-Neftekhim"	1279	833	1	1
VOJSC "Khimprom", Volgograd	5768	7115	5	7
Total:	108565	106219	100	100

Application

Biodiesel

Lutefisk cod at the Norwegian Constitution Day celebrations

Sodium hydroxide is the well-known caustic soda, the most common alkali in the world. Chemical formula NaOH. It has other traditional names - caustic, caustic alkali, caustic soda, sodium hydroxide, sodium alkali.

Caustic soda is solid white or yellowish in color, slightly slippery to the touch, which is obtained by electrolysis from sodium chloride. Sodium hydroxide is a strong alkali that can destroy organic matter: paper, wood, and also human skin, causing burns varying degrees gravity.

Properties of sodium hydroxide

The industry produces sodium hydroxide in the form of a white, odorless, crumbly powder. Technical caustic soda can be supplied in the form of various solutions: mercury, chemical, diaphragm. Usually it is a colorless or slightly colored liquid, hermetically sealed in an alkali-resistant container. Granular sodium hydroxide is also produced, which serves various technical needs.

Caustic is a water-soluble substance that, when in contact with water, releases a large amount of heat. The sodium lye solution is slightly slippery to the touch, reminiscent of liquid soap.

Other properties of sodium hydroxide

Insoluble in acetone, ethers;
It dissolves well in glycerin, ethanol and methanol (alcohol solutions);
Caustic is very hygroscopic, so soda must be packaged in a waterproof container and stored in a dry place;
Non-flammable, melting point - 318°C;
Boiling point - 1390°C;
The dangerous property of sodium hydroxide is its violent reaction upon contact with metals such as aluminum, zinc, lead, and tin. Being a strong base, caustic soda can form an explosive flammable gas (hydrogen);
A fire hazard also arises when sodium alkali comes into contact with ammonia;
When molten, it can destroy porcelain and glass.

IN industrial scale You should use this substance carefully, since failure to comply with safety measures is dangerous for humans.

Applications of sodium hydroxide

IN Food Industry sodium alkali is known as a food additive - acidity regulator E-524. It is used in the production of cocoa, caramel, ice cream, chocolate and lemonade. Caustic soda is also added to bakery products and baked goods for a more fluffy consistency, and treating the products with caustic soda solution before baking helps to acquire a crispy, golden brown crust.

The use of sodium hydroxide is advisable to obtain a delicate and soft consistency of products. For example, soaking fish in an alkaline solution produces a jelly-like mass from which lutefisk is prepared, a traditional Scandinavian dish. The same method is used to soften olives.

Sodium hydroxide is used quite widely in the cosmetics industry. In the production of personal care products (soaps, shampoos, creams), as well as detergents, sodium hydroxide is necessary for saponification of fats and is present as an emulsifying alkaline additive.

Other uses of sodium hydroxide:

In the pulp and paper industry;
For the production of oils and the production of biodiesel in the oil refining industry;
For disinfection and sanitization premises, since caustic soda has the property of neutralizing substances in the air that are harmful to humans;
In everyday life for cleaning clogged pipes, as well as for eliminating dirt from various surfaces (tiles, enamel, etc.).

Why is caustic soda dangerous?

When it comes into contact with human skin, mucous membranes or eyes, sodium hydroxide causes quite severe chemical burns. It is necessary to immediately wash the affected area of the body big amount water.

If accidentally swallowed, it causes damage (chemical burns) to the larynx, oral cavity, stomach and esophagus. As first aid, you can give the victim a drink of water or milk.

general characteristics

The scientific name of the additive E524 is sodium hydroxide or caustic soda. This very aggressive substance of synthetic origin has no analogues in nature. Under natural conditions, it takes the form of white scales or small soap granules to the touch.

Nowadays, it is widely used in various sectors of life, including medicine, pharmacology, and the food industry. IN agriculture For example, caustic soda is used to test cow's milk for impurities. This substance is used in production different types household chemicals(the most popular ones are for cleaning water and sewer pipes). In cosmetology, caustic soda is added to shampoos, soaps, nail polish removers, creams, as well as products for getting rid of dead skin. In addition, sodium hydroxide is an indispensable substance in the oil refining, pulp and paper industries and in the production of diesel fuel.

In the food industry, sodium hydroxide is used to regulate acidity, as a stabilizer and emulsifier. Despite the very aggressive properties and an impressive list side effects, caustic soda as food additives allowed all over the world.

Dangerous properties of caustic soda

Caustic soda is a rather dangerous substance. Upon contact with it, deep and very painful wounds form on the skin and mucous membranes. Contact of caustic soda with the eyes is very dangerous, as it causes atrophy of the optic nerve, which leads to blindness. If you accidentally inhale caustic soda powder, you will experience a severe coughing attack, shortness of breath, a sore throat, and even possible swelling of the respiratory lungs. And one can only imagine what this substance can do to our internal organs. If you accidentally swallow caustic soda, severe pain and a burning sensation will appear in the abdomen very quickly, and anaphylactic shock is possible. If there is the slightest suspicion of sodium hydroxide poisoning, it is important to call immediately. ambulance. Areas of skin affected by caustic soda should be washed with a mild solution of boric or acetic acid, mucous membranes – clean water, eyes – first treat very weak solution boric acid and then water.

Although sodium hydroxide is used in microdoses in the food industry, side effects are possible with regular consumption of food containing E524.

What may it contain?

The food additive E524 can be contained in a wide variety of product groups, in which it performs the most different functions. Take, for example, jams and marmalades, which often contain sodium hydroxide. In this group of products, the additive plays the role of a regulator and stabilizer of acidity levels. If you add a certain amount of caustic soda to the baking dough, the finished product will receive a beautiful golden brown crust.

The most famous baked goods made with caustic soda are German bagels. Black canned ones get theirs dark color and characteristic consistency also thanks to the addition of E524. In products made from or other types of fats, sodium hydroxide accelerates the breakdown. This additive also comes to the rescue when you need to quickly and easily peel the fruit. To do this, fruits, berries or vegetables are simply treated with caustic soda. In addition, the acidity regulator E524 is used in the production of fermented milk products and various types of sweets.

Sodium hydroxide is dangerous chemical compound. And although in the food industry E524 is used in small doses that usually do not pose a danger to humans, excessive caution does not hurt. If you don’t want or can’t give up E-containing foods yourself, then try to at least minimize the number of “foods” in the diet of young children. And for this, do not forget to check what it consists of before purchasing a product.

One of the important chemical compounds synthesized in huge quantities every year is alkali sodium hydroxide. It has earned such popularity due to its properties. the formula of which is NaOH, is of great industrial importance for humans. Let's consider this substance more details.

History of the discovery of the substance

The first mention of a compound whose properties are reminiscent of caustic soda appears in ancient times. Even the Bible contains some information about the substance neter, extracted from the Egyptian lakes. Presumably this was caustic soda.

Aristotle, Plato and other ancient Greek and Roman philosophers and scientists also mentioned the substance nitrum, which was extracted from natural reservoirs and sold in the form of large differently colored pieces (black, gray, white). After all, nothing was known about purification methods at that time, so it was not possible to separate the compound from the coal that polluted it.

Soap making was introduced in 385 BC. The process was based on caustic soda. Its formula, of course, was not yet known, but this did not stop it from being extracted from the ash of plants of the Solyanka genus, from lakes and used for cleaning household items, washing clothes, and making various soaps.

A little later, the Arabs learned to add essential oils, aromatic substances. Then the soap became beautiful and smelling good. It was beginning active development soap making processes and technologies.

Until the 17th century, caustic soda, the properties of which were widely used, remained unstudied as a chemical compound. It was combined with substances such as soda and sodium hydroxide. All of them were called caustic alkalis.

Later, the scientist Duhamel du Monceau was able to prove the difference between these substances and divided them into alkalis and salts. Since then, caustic soda has received its true and permanent today Name.

Synonyms of names

It should be noted that the name of this substance is not the same and has several synonyms. In total there are 6 different options:

sodium hydroxide;
caustic soda;
caustic soda;
sodium lye;
caustic;
caustic alkali.

This compound is called caustic soda in common people and industry. In chemical syntheses, it is more correct to say sodium alkali or caustic soda. This does not change the formula. The most common name is caustic. The correct name from the point of view of the systematic nomenclature of substances is sodium hydroxide.

Chemical formula and molecule structure

If we consider this substance from a chemical point of view, it will consist of two ions: sodium cation (Na +) and hydroxide anion (OH -). Bonding with each other due to the electrostatic attraction of differently charged particles, these ions form caustic soda. The empirical formula will be NaOH.

The hydroxo group is formed between oxygen and hydrogen, while it is held in an ionic bond with sodium. In solution, alkali completely dissociates into ions, being a strong electrolyte.

Laboratory method of obtaining

Industrial and laboratory methods for producing caustic soda closely overlap. It is often obtained in small quantities by chemical and electrochemical methods in smaller installations than in industrial facilities. And tons of the substance are produced using the same methods in huge columns of electrolyzers.

There are several main methods for synthesizing caustic in the laboratory.

Ferritic method. It consists of two main stages: in the first stage, sintering occurs under the influence of high temperature sodium carbonate and iron (III) oxide. As a result, sodium ferrite (NaFeO 2) is formed. In the second stage, it is exposed to water and decomposes to form sodium hydroxide and a mixture of iron and water (Fe 2 O 3 *H 2 O). The resulting caustic soda is evaporated from the solution to white crystals or flakes. Its purity is approximately 92%.
Lime method. It consists of a reaction between sodium carbonate and calcium hydroxide to form calcium carbonate and caustic soda. The reaction is carried out at a temperature of 80 o C. Since the resulting salt precipitates, it is easily separated. The remaining solution is evaporated and sodium alkali is obtained.
Diaphragm and membrane production methods. Based on the operation of the electrolyzer installation. It is fed with a solution of table salt (NaCL), which undergoes electrolysis to form free chlorine gas and the desired caustic product. The difference between these methods is that with the diaphragm method the main structural part The device is an asbestos diaphragm (cathode). With the membrane method, the cathode and anode spaces are separated by a special membrane.

This is how sodium hydroxide is obtained in the laboratory, choosing the most financially advantageous option. It is also, as a rule, less energy-consuming.

Synthesis in industry

How is such a substance as caustic soda produced in industry? Liquid and solid caustic soda is most often extracted using the electrochemical method. It is based on the electrolysis of a solution of the natural mineral halite, the vast majority of which is formed by table salt.

The main feature of this synthesis is that by-products together with caustic soda are gaseous chlorine and hydrogen. The process is carried out in any of three options:

diaphragm electrolysis on a solid cathode;
with a liquid mercury cathode;
membrane with a solid cathode.

The vast majority of caustic soda produced in the world is formed using the membrane method. The resulting alkali is quite different high level cleanliness.

Areas of use

There are quite a few industries in which caustic soda is relevant. The application is based on its chemical and physical properties, making this compound indispensable in many syntheses and processes.

There are several main areas in which sodium hydroxide is an essential element.

Chemical production (synthesis esters, soaps, fats, obtaining fibers, etching aluminum, for obtaining petroleum products, as a catalyst in many processes; is the main substance for neutralizing acids and their corresponding oxides; V analytical chemistry used for titration; also used to obtain pure metals, many salts, other bases and organic compounds).
In the production of paper for processing wood pulp (getting rid of lignin from wood).
IN economic activity Caustic soda is also indispensable for humans. The use of numerous detergents and cleaning products based on it is very important. Soap making, shampoo production - all this cannot be done without caustic soda.
Necessary for biofuel synthesis.
It is used on a national scale for degassing and neutralizing effects on organisms.
Production of medicines and narcotic drugs.
Food industry - confectionery, chocolate, cocoa, ice cream, coloring of sweets, olives, baking of bakery products.
In cosmetology for the removal of foreign formations (moles, papillomas, warts).
Used in distilleries and tobacco factories.
In the textile industry.
Production of glass: colored, regular, optical and others.

It is obvious that sodium hydroxide is a very important and useful substance in human activity. It is not in vain that it is synthesized in the world annually in tons - 57 million or more.

Physical properties

White powdery substance, sometimes colorless. It can be in the form of a fine crystalline powder or in the form of flakes. Most often in the form of large crystals. The melting point is quite low - 65.1 o C. It absorbs moisture very quickly and turns into the hydrated form of NaOH 3.5H 2 O. In this case, the melting point is even lower, only 15.5 o C. It dissolves almost unlimitedly in alcohols and water . It feels both solid and liquid soapy.

Very dangerous in concentrated and diluted form. It can damage all the membranes of the eye, including the optic nerves. Contact with eyes may result in blindness. Therefore, working with this connection is extremely dangerous and requires protective equipment.

Chemical properties

Caustic soda exhibits exactly the same properties as all alkalis: it interacts with oxides, amphoteric oxides and hydroxides, and salts. Of the non-metals, it reacts with sulfur, phosphorus and halogens. Also capable of reacting with metals.

IN organic chemistry Sodium hydroxide reacts with amides, ethers, and halogenated alkanes.

Storage conditions

Storage of caustic soda is carried out under certain conditions. This is because it is extremely reactive, especially when the room is damp. The main conditions are the following.

Storage away from heating devices.
Hermetically sealed and sealed packages that do not allow moisture to pass through.
Dry crystalline caustic is stored in bags of a special composition (dense polyethylene), liquid - in dark glass containers with ground stoppers. If the quantity is large and requires transportation, then the caustic soda solution is placed in special steel containers and canisters.

This substance can be transported by any in a known way in compliance with safety regulations, excluding transportation by air.

Liquid sodium lye

In addition to crystalline, there is also water solution caustic soda. Its formula is the same as for solid. Chemically, solutions are more applicable and convenient to use. Therefore, caustic is used more often in this form.

Caustic soda solution, the formula of which is NaOH, is used in all of the above areas. It is only inconvenient during transportation, since it is better to transport dry caustic. In all other properties it is in no way inferior to crystals, and in some even surpasses them.