One of the important chemical compounds synthesized by huge parties every year, is a caustic sodium hydroxide.Such popularity it deserved due to their properties.Caustic soda, which formula - NaOH, is of great commercial importance to humans.We consider this matter in more detail.
History of discovery material
first mention of the compound, it is reminiscent of the properties of sodium hydroxide, appearing in ancient times.Even the Bible contains some information on the substance neter, extracted from Egyptian lakes.Presumably this was caustic soda.
Aristotle, Plato and other ancient Greek and Roman philosophers and scientists also mentioned substance nitrum, which is extracted from natural reservoirs and sold in the form of large pieces of differently colored (black, gray, white).After all, the methods of purification did not yet know anything, so the connection is separate from the coal, polluting it was not possible.
In 385 BC found the use of soap-making.The basis of the process used caustic soda.The formula of it, of course, was not known yet, but this did not prevent him from ash to produce plants of the genus Salsola, from lakes and used for cleaning household items, laundry, manufacturing various soaps.
Later Arabs learned how to add the product to the essential oils, aromatic substances.Then the soap was a nice and pleasant-smelling.It began active development of processes and technologies soap making.
Until the XVII century caustic soda, whose properties are used in full, as a chemical compound remained unstudied.Its combined with substances such as soda, potassium hydroxide, potassium carbonate, sodium.All of them were called caustic alkali.
later Duhamel du Monceau scientist was able to prove the difference between these substances and divided them into alkali and salt.Since then, caustic soda and received his true and constant to this day the name.
names Synonyms
It should be noted that the name of the substance is not the same and has a few synonyms.Total may be designated 6 different options:
- sodium hydroxide;
- sodium hydroxide;
- caustic soda;
- sodium alkali;
- caustics;
- caustic alkali.
caustic soda, this compound is called the common people and the industry.The chemical synthesis of more correct to say sodium lye or caustic soda.The formula remains the same.The most ordinary name - caustics.Right from the point of view of systematic nomenclature of substances is the name of sodium hydroxide.
chemical formula and the structure of the molecule
If we look at the substance in terms of chemistry, it will consist of two ions: the sodium cation (Na +) and hydroxide anion (OH-).Communicating with each other due to electrostatic attraction raznozaryazhennyh particles, these ions form sodium hydroxide.Empirical formula of the form is NaOH.
gidroksogrupp polar covalent bond is formed between the oxygen and hydrogen, wherein it is held with sodium ion bond.The alkali solution is completely dissociates into ions, being a strong electrolyte.
Laboratory method for producing
Industrial and laboratory methods for producing caustic soda closely overlap.Often, small amounts of it is produced by chemical and electrochemical methods in smaller units than in industrial facilities.A ton of the substance produced by the same methods in the huge colonies of cells.
There are several basic methods for the synthesis of caustic soda in the laboratory.
- Ferritic method.It consists of two main stages: the first sintering occurs under heat, sodium carbonate and iron oxide (III).This produces sodium ferrite (NaFeO2).At the second stage, it is exposed to water and decomposes to form sodium hydroxide and mixtures of iron with water (Fe2O3 * H2O).The resulting caustic soda solution is evaporated to from crystals or white flakes.Its purity was about 92%.
- lime method.Is the coupling reaction between sodium carbonate and calcium hydroxide (slaked lime) to form calcium carbonate and caustic.The reaction is conducted at a temperature of 80C.Since the resulting salt precipitates, it is easy to separate.The remaining solution was evaporated to give the sodium alkali.
- diaphragm and the membrane production process.Based on the installation of the cell.It is fed a solution of sodium salt (NaCL), which is electrolyzed to form chlorine gas and free the desired product caustic.The difference of these methods is that when the process diaphragm main structural part of the device is a diaphragm of asbestos (cathode).The membrane process cathode and anode space is divided by a special membrane.
thus obtained in the laboratory and sodium hydroxide, choosing the most favorable option in material terms.He is, as a rule, less energy-intensive.
Synthesis industry
How to get in the industry such substance as sodium hydroxide?Liquid and solid caustic soda is produced mostly by the electrochemical method.It is based on the electrolysis of a solution of a natural mineral halite, the vast majority of which is formed with sodium chloride.
The main feature of this synthesis is that the by-products with sodium hydroxide is chlorine gas and hydrogen.The process is carried out in any of the three options:
- diaphragm electrolysis on a solid cathode;
- liquid mercury cathode;
- membrane with a solid cathode.
vast majority of the world's caustic yet produced by the method of the membrane.The resulting alkali differs sufficiently high level of purity.
Applications
There are many industries in which the actual caustic soda.The application is based on its chemical and physical properties, making this compound indispensable in many syntheses and processes.
There are several key areas in which the sodium hydroxide - a required element.
- Chemical production (synthesis of esters, soaps, fats, obtaining fibers etching aluminum to produce refined products, as a catalyst in many processes, a basic substance to neutralize the acids and their corresponding oxides and in analytical chemistry is used for the titration; andused to produce pure metals, many salts, bases and other organic compounds).
- the production of paper for the treatment of wood pulp (getting rid of the wood material lignin).
- in human economic activity is also indispensable caustic soda.The use of many detergents and cleaning products on its basis is very important.Soap, shampoo receipt - all this is not without caustic soda.
- required for the synthesis of biofuels.
- applied on a national scale for the degassing and neutralizing toxic substances that affect the body.
- production of medicines and drugs.
- Food industry - confectionery, chocolate, cocoa, cream, coloring sweets, olives, pastries baked goods.
- in cosmetology to remove foreign entities (birthmarks, papillomas, warts).
- used on alcoholic beverages and tobacco mills.
- In the textile industry.
- Glass: color, conventional, optical and other.
Obviously, sodium hydroxide - a very important and useful in human substance.It is not for nothing that it is synthesized in the world each year in tonnes - 57 million or more.
physical properties
white powdery substance, sometimes colorless.It may be in the form of fine crystalline powder or in the form of flakes.Often in the form of large crystals.The melting point is low enough - 65,1oS.Very quickly absorbs moisture and becomes hydrated form NaOH ยท 3,5N2O.In this case, the melting point of even smaller total 15,5oS.Virtually unlimited soluble in alcohols, water.At the touch of both solid and liquid soapy.
very dangerous in concentrated and diluted form.Can damage all of the eye up to the optic nerve.Eye contact can result in blindness.Therefore, the work with the connection is extremely dangerous and requires protective devices.
chemical properties
Caustic Soda properties are exactly the same as all the bases: reacts with acids, acid oxides, amphoteric oxides and hydroxides, salts.Of Nonmetallic reacts with sulfur, phosphorus and halogens.Also capable of reacting with metals.
In organic chemistry, sodium hydroxide reacts with amides, esters, halogenated alkanes.
Storage
Storage caustic soda is carried out under certain conditions.This is because it is extremely reactive, especially when wet room.The main conditions are the following.
- Store away from heating devices.
- hermetically closed and sealed packaging are not able to pass moisture.
- dry crystalline caustic stored in bags of special composition (density polyethylene), a liquid - in a dark glass container with a glass stopper.If the number is large and it requires a transport of sodium hydroxide solution was then placed in special containers and steel cans.
carrying this substance may be any known method in compliance with safety regulations, excluding transportation by air.
liquid sodium alkali
crystalline addition, there is an aqueous solution of sodium hydroxide.It is the same formula as for the solid.Chemically solutions more useful and convenient to use.Therefore, in this form of caustics used frequently.
solution of sodium hydroxide whose formula - NaOH, is used in all of these areas.He only inconvenient at transportation as better transport dry caustic.For all other properties, it does not yield crystals, and some exceed them.
