Most people know very well what an acid or a salt is. It is difficult to find a person who has not held a bottle of vinegar in his hands or has not used a food product in his life, without which almost any food seems bland and tasteless. But what is alkali? Is this the same as a foundation or not? How is it different from acid? Such questions can puzzle anyone, and therefore let us allow ourselves to refresh the knowledge that was once acquired at school.
Alkali - what is it?
Let's start with the fact that compounds of metals with water in chemistry are usually called hydroxides. A substance of this type, formed by ammonium, is alkaline or is called alkali. In turn, the base is an electrolyte, which, in addition to hydroxide ions (OH -), contains no other anions. Thus, we can say that an alkali is any soluble base. Only metals of subgroups Ia and IIa (those that come after calcium) can form such a hydroxide. An example of such compounds is sodium alkali (formula NaOH), caustic baryate (Ba(OH) 2), potassium hydroxide (KOH), cesium hydroxide (CsOH), etc. They are solid white substances, which are characterized by high hygroscopicity.
Properties of alkalis
The dissolution of such compounds in water is accompanied by significant heat generation. In group Ia the strongest alkali is cesium hydroxide, and in group IIa it is radium hydroxide. An example of a weak compound of this type is caustic alkalis that can dissolve in ethanol and methanol. In the solid state, all these substances absorb water and carbon dioxide from the air and slowly turn into carbonates. The most important property of alkali is that as a result of its reaction with an acid, a salt is formed - this feature is very often used in industry. These compounds can carry electric current and are therefore often used as electrolytes. Alkalies are obtained by electrolysis of chlorides or through the interaction of oxides with water. In industry, the first method is usually used, and the second is used mostly for the production of slaked lime. Fat dissolves in an alkaline environment, and this property is widely used in soap making. A number of bases can destroy plant matter, irritate skin and destroy clothing. Alkalis can react with some metals (such as aluminum) and can protect steel from corrosion. They are resistant to heat - sodium hydroxide can be melted and brought to a boil, but it will not decompose.
This makes alkalis very different from insoluble bases, some of which (for example, silver hydroxide) decompose even at room temperature. Just like acids, these substances require great care and high safety requirements. Goggles are usually worn to protect the eyes when working with alkali. They can only be stored in special containers - drinking containers are completely unsuitable for this.
Alkalis form hydroxides of alkali metals of group 1 of the main subgroup when dissolved in water.
Physical properties: solutions of alkalis in water are soapy to the touch, they corrode skin, fabrics, paper - caustic alkalis(caustic soda NaOH, caustic potassium KOH). On the skin they cause long-lasting wounds. Very hygroscopic.
Chemical properties LiOH, NaOH, KOH, RbOH, CsOH. In this series, the strength and solubility of alkalis increases, which is associated with an increase in the size of alkali metal ions (cations) and a weakening of electrostatic attraction with the hydroxide group (anion). Alkalies include the hydroxide of the alkaline earth metal barium – Ba(OH)2.
Alkalis– strong bases, chemically very active substances. When they are dissolved in water, a large amount of heat is released.
In an aqueous solution, alkalis dissociate:
Chemical properties of alkalis:
1) alkalis react with neutralization with acids, forming salt and water:
2) interact with acidic oxides, forming both medium and acidic salts:
in ionic form:
3) enter into an exchange reaction with medium salts: CuSO4 + KOH = Cu(OH)2 + K2SO4, with acidic salts: NaHSO4 + KOH = Na2SO4 + K2SO3 + H2O (redox);
4) alkali solutions react with amphoteric oxides - complex salts are formed: Al2O3 + NaOH + 7H2O = 2Na;
5) when solid alkalis are fused with amphoteric metal oxides, double anhydrous salts are formed: Al2O3 + 2NaOH = 2NaAlO2 (sodium metaaluminate);
6) interact with halogens depending on temperature conditions - in the cold: Cl2 + 2NaOH = NaClO + NaCl + H2O, when heated: 3Cl2 + 6NaOH = NaClO3 + 5NaCl + 3H2O;
7) interact with some organic substances: C2H5OH + NaOH = C2H5ONa + H2O;
8) solutions and melts of alkalis undergo electrolysis
Receipt:
1) reaction of metals with water: 2K + 2H2O = 2KOH + H2;
2) reaction of metal oxides with water: 2K2O + 2H2O = 2KOH.
Application: NaOH and KOH are used in the production of soap, paper, textile industry, etc.
Alkali (synonym - alkali) is the name of any of the soluble hydroxides of alkali metals, that is, lithium, sodium, potassium, rubidium and cesium. Alkalis are strong bases and react with acids to produce neutral salts. They are caustic and, in concentrated form, are corrosive to organic tissue. The term alkali is also applied to soluble hydroxides of the alkaline earth metals such as calcium, strontium and barium, as well as ammonium hydroxide. The name of the substance, alkali, was originally applied to the ashes of burned plants containing sodium or potassium, from which oxides of sodium or potassium could be leached.
Among all alkalis produced by industry, the largest share of such production is accounted for by the production of soda ash (Na2CO3 - sodium carbonate) and caustic soda (NaOH - sodium hydroxide). The next alkalis in terms of production volume are potassium hydroxide (KOH-caustic potash) and magnesium hydroxide (Mg(OH)2-magnesium hydrate).
The production of a wide range of consumer products depends on the use of alkalis at some stage. Soda ash and caustic soda are important in the production of glass, soap, rayon, cellophane, paper, cellulose, detergents, textiles, water softeners, some metals (especially aluminum), bicarbonate of soda, gasoline and many other petroleum products and chemicals. .
A few historical moments from the history of alkali production.
People have been using alkali for centuries, obtaining it first from leaching (aqueous solutions) of certain desert lands. Until the late 18th century, leaching from wood ash or seaweed was the main source of alkalis. In 1775, the French Academy of Sciences offered cash prizes for new production methods alkalis. The Soda Ash Prize was awarded to the Frenchman Nicolas Leblanc, who in 1791 patented a process for converting sodium chloride into sodium carbonate.
The Leblanc method of production dominated world production until the end of the 19th century, but after the First World War it was completely replaced by another method of salt conversion, which was improved in the 1860s by Ernest Solvay of Belgium. At the end of the 19th century, electrolytic methods for the production of caustic soda appeared, the volumes of which grew rapidly.
According to the Solvay method, the ammonia-soda process for the production of soda ash proceeded as follows: table salt in the form of a strong brine was chemically treated to eliminate calcium and magnesium impurities and then saturated with recirculating ammonia gas in towers. The ammonia brine was then gassed using carbon dioxide gas at moderate pressure in another type of tower. These two processes produce ammonium bicarbonate and sodium chloride, the double decomposition of which produces the desired sodium bicarbonate as well as ammonium chloride. The sodium bicarbonate is then heated until it decomposes into the desired sodium carbonate. The ammonia involved in the process is almost completely reduced by treatment with ammonium chloride and lime to produce ammonia and calcium chloride. The recovered ammonia is then reused in the processes described above.
The electrolytic production of caustic soda involves the electrolysis of a strong saline solution in an electrolytic cell. (Electrolysis is the breaking down of a compound in solution into its constituents using an electric current to produce a chemical change.) Electrolysis of sodium chloride produces chlorine, sodium hydroxide, or sodium metal. Sodium hydroxide in some cases competes with sodium carbonate in the same application processes. And in any case, both are interconvertible through fairly simple processes. Sodium chloride can be
converted into an alkali by one of two processes, the difference between them being only that the ammonia-soda reaction process produces chlorine in the form of calcium chloride, a compound of little economic importance, while electrolytic processes produce elemental chlorine, which has innumerable uses in the chemical industry industry.
Significant mineral reserves exist in several places in the worldform of soda ash, known as natural lye. Such deposits produce most of the world's natural alkali from vast deposits in underground mines.
Natural sodium metal.
Read the article Alkalis (source: Chemist's Encyclopedic Dictionary) and get a better idea of what alkali is, or watch a video about this chemical reagent.
Use of alkali in our environment
Alkali has found widespread use in our lives. Alkali can provide some form of water softening and remove impurities such as manganese, fluorides and organic tannins. Heavy industries use alkali in the form of lime to absorb and neutralize sulfur oxides in air emissions, thereby reducing the likelihood of acid precipitation. Sulfur dioxide produced by industrial plants and released into the atmosphere returns to the earth in the form of acid rain or sulfuric acid. Such areas exposed to acid rain are treated by aircraft with preparations that contain alkali. This makes it possible to control and neutralize the critical pH level of water and soil in areas where such man-made emissions occurred. Adding alkali to waste and wastewater, maintaining the correct pH level in oxidative processes during their decomposition. Stabilizes sediment formation in wastewater and reduces odor or formation of pathogenic bacteria. Sludge from wastewater bodies treated with quicklime complies with environmental standards, which makes it suitable for further use as fertilizer on agricultural lands.
Industrial applications of alkali
In industrial and mining operations, the use of alkalis in wastewater helps to neutralize harmful compounds and purify them. Treatment with excess alkali increases the pH of the water to 10.5-11 and can disinfect the water and remove heavy metals. Alkalis such as lime are key in the chemical production of calcium carbide, citric acid, petrochemicals and magnesia. In the paper industry, calcium carbonate is a causticizing agent for bleaching. The steel industry depends on lime as a component to remove impurities such as carbon monoxide gas, silicon, manganese and phosphorus.
Detergents formed by alkali
Alkaline detergents help in cleaning heavily soiled surfaces. These economical, water-soluble alkalis with a pH range of 9 to 12.5 can neutralize acids in a variety of types of dirt and deposits.
Alkali in glass and ceramics production
Alkali is the main raw material in glass production. Limestone, as well as sand, soda ash, lime and other chemicals, are fired at extremely high temperatures and turned into a molten mass. Glassblowers and potters use alkalis for glazes and fluxes, which react with acids to form silicates (glass) when heated. Concentrated alkalis create richer color in the glaze.
Literature about alkali
In the book by I. Nechaev "Stories about the Elements", published in 1940, in accessible and understandable language for the average person 
talks about what alkali is and how it differs from another caustic substance - acid. Excerpt from the text:
“Among the numerous substances that chemists have used in their laboratories since ancient times, caustic alkalis have always occupied a place of honor - caustic potassium and caustic soda. Hundreds of different chemical reactions are carried out in laboratories, factories and in everyday life with the participation of alkalis. With the help of caustic potassium and sodium can, for example, make most insoluble substances soluble, and the strongest acids and suffocating vapors can, thanks to alkalis, be deprived of all their pungency and toxicity.
Caustic alkalis are very peculiar substances. In appearance, these are whitish, rather hard stones, seemingly unremarkable in anything. But try taking caustic potassium or soda and holding it in your hand. You will feel a slight burning sensation, almost like touching nettles. Holding caustic alkalis in your hand for a long time would be unbearably painful: they can eat away the skin and meat to the bone. That is why they are called “caustic”, in contrast to other, less “evil” alkalis - the well-known soda and potash. By the way, caustic soda and potassium were almost always obtained from soda and potash.
Caustic alkalis have a strong attraction to water. Leave a piece of completely dry caustic potassium or soda in the air. After a short time, liquid will appear on its surface from nowhere, then it will all become wet and loose, and in the end it will spread out into a shapeless mass, like jelly. It is the alkali from the air that attracts water vapor and forms a thick solution with moisture. Whoever has to immerse his fingers in a solution of caustic alkali for the first time declares in surprise: “Like soap!” And this is absolutely correct. Lye is slippery, like soap. Moreover, soap feels “soapy” to the touch because it is made using alkalis. The solution is a caustic alkali and tastes like soap.
But a chemist recognizes caustic alkali not by its taste, but by how this substance behaves with litmus paint and acids. A piece of paper soaked in blue litmus dye instantly turns red when it is dipped into acid; and if you touch the alkali with this reddened piece of paper, it immediately turns blue again. Caustic alkali and acid cannot exist peacefully side by side for even a single second. They immediately enter into a violent reaction, hissing and heating up, and destroy each other until there is not a grain of alkali or a drop of acid left in the solution. Only then does calm come. The alkali and acid “neutralized” each other, they say in such cases. By combining them together, a “neutral” salt is obtained - neither sour nor caustic. So, for example, from the combination of hot hydrochloric acid with caustic soda, ordinary table salt is obtained."
Distinctive features of alkali.
From what we have read above, we already know that the opposite of alkali is acid. Instead of bitter taste 
inherent in alkalis, acids tend to have a sour taste. An example would be foods such as lemons or fruit vinegar (diluted), which are inherently acidic foods and contain acid in their composition. We can determine whether a substance is alkali or acid by knowing its pH. pH levels are measured using a pH scale; this scale ranges from 0-14, and these numbers tell us whether a substance is an alkali or an acid. Pure distilled water has a pH level of 7 and is called neutral (right in the middle of the scale). Any substance that has a pH above 7 is an alkaline substance, which may also be called an alkali. And, any other substance that has a pH below 7 is an acid.
Why is the substance alkaline?
So we already know that the pH level is a scale whose values range from 0-14 and indicate whether a substance is alkaline or acidic. However, we don't really know why. Let's look at this issue in more detail.
The pH level of a substance depends on how the atoms are arranged and combined in the substance. Pure water sits right in the middle of the scale and has a pH of 7. This means it contains equal amounts of hydrogen atoms (H+) and hydroxide atoms (OH-). When a substance has more hydrogen atoms (H+), it is an acid. When a substance has more hydroxide atoms (OH-), it is alkaline.
Where to buy lye?
You can buy alkali in Novosibirsk with a purity grade of analytical grade (pure for analysis) in the “For Business” store on the orders page: or. For non-resident buyers, goods can be sent by Russian Post or transport companies.
Alkalis are bases that are highly soluble in water. The following alkalis are widely used in clinical and sanitary laboratories: caustic ammonium - a solution of ammonia in water (see Ammonia), (see), caustic potassium (see).
Contact of workers with alkalis is possible when performing such production operations as crushing and transporting solid alkalis, loading into and unloading devices, packaging the finished product, cleaning and repairing equipment, etc.
When constantly working with alkalis, chronic skin lesions are possible - swelling and softening of the skin, ulcers, etc. Inhalation of alkali in the form of dust or mist causes irritation of the mucous membranes of the respiratory tract.
Prevention: mechanization of crushing processes and sealing of devices, equipment of ventilated shelters over places of possible release of alkali, use of special clothing, rubber gloves, glasses, respirators, etc. The maximum permissible concentration of alkali aerosol in the air of production premises in terms of caustic soda is 0.5 mg /m 3.
First aid: abundant rinsing of the affected parts of the body with water, for which special hydrants should be installed in work areas, then with a 5% solution of acetic, hydrochloric or citric acids. If alkali gets into the eyes, rinse for a long time with a stream of water, then drip a 2% solution of novocaine or 0.5% solution of dicaine.
See also Burns (chemical), Poisoning (alkali).
Alkalis (caustic alkalis) are bases that are highly soluble in water. The following alkalis are widely used in practice: sodium hydroxide (caustic soda, caustic soda; NaOH), potassium hydroxide (caustic potassium, caustic potash; KOH), barium hydroxide [caustic barium; Ba(OH) 2 ], ammonium hydroxide (ammonium hydroxide, ammonia, volatile alkali; NH 4 OH).
In their pure form, alkalis are solid substances that are highly soluble in water. In aqueous solutions, alkalis almost completely disintegrate into ions, as a result of which they are classified as strong bases. Only ammonium hydroxide, which is not obtained in a free state and exists only in solutions, is a weak base; It is formed when ammonia is dissolved in water.
Aqueous solutions of alkalis have all the properties inherent in solutions of bases. The table shows the relationship between the density, percentage and molar concentrations of aqueous solutions of alkalis, most widely used in biochemical, sanitary-hygienic and clinical laboratories.
See also Acids and bases.
Occupational hazards in the production of alkalis. The effect of alkalis on the body is due to the ability to remove water from tissues and destroy proteins, forming alkaline albuminates, as well as saponify fats. Under the influence of alkali, soft, easily removable scabs are formed on the skin, which do not prevent the alkali from penetrating into the deeper layers of tissue.
With constant contact with alkali, even moderate concentrations, chronic skin damage, painful ulcers and limited dermatitis are observed. Eczema is observed less frequently. The reason for their occurrence, apparently, is the combined effect of alkalis and other harmful factors, since degreasing the skin and damage to the epidermis disrupts the barrier functions of the skin, facilitating the penetration of infection and the influence of other (physical and chemical) factors.
Under the influence of alkali, nails become thinner, become brittle, and become covered with longitudinal grooves that turn into cracks. With prolonged exposure to alkali, these changes can become permanent.
Getting even small amounts of alkali into the eye is especially dangerous, as it causes damage not only to the mucous membrane and cornea, but also to its deeper environments. As a result, vision loss may occur. The effect of alkalis on the respiratory system causes irritation of the mucous membranes of varying degrees of severity.
Severe poisoning with a burn of the mucous membrane and subsequent scarring, leading to esophageal obstruction, is observed with accidental ingestion of concentrated alkali solutions.
Contact of workers with alkalis is possible during crushing and transportation of solid alkalis, during loading them into devices for preparing solutions, during filtration of solutions, melting alkalis, especially in the production of metal sodium and potassium, during unloading and packaging of finished products in bulk, liquid and molten form (in the production of caustic alkalis and alkali metals). Equipment cleaning and repair operations are especially dangerous in this regard.
The concentration of alkaline substances in the air of industrial premises varies.
The maximum permissible concentration of alkaline aerosol in terms of caustic soda is 0.5 mg/m 3 .
First aid for alkali poisoning - see Poisoning, Antidotes.
Prevention. In order to prevent industrial alkali poisoning, it is necessary to implement a continuous, sealed production process, if possible eliminating manual operations and mechanizing labor-intensive processes. Of great importance for improving working conditions is rational ventilation with covering of equipment and installation of suction systems at places where dust and gases may be released.
Workers must be provided with protective clothing, rubber gloves and safety glasses with leather frames. It is advisable to use respirators or cotton-gauze dressings. Exposed parts of the body are lubricated with Vaseline or special pastes. After work, alkaline dust should be washed off with oil, then rinsing the skin with warm water. At the end of work, work clothes and underwear are cleaned and washed. In work areas, special eye hydrants with a lever tap for quick water release, hydrants with a flexible hose designed for washing affected parts of the body, as well as sinks with cold and hot water for washing hands are installed.
If quicklime gets into your eyes, wash them immediately and treat the mucous membrane with a 15% solution of neutral tartaric ammonium. For severe pain, a 2% solution of novocaine with adrenaline is administered dropwise.
In case of a burn with quicklime, you should immediately remove traces of lime with vegetable or mineral oil, and then apply lotions from a 5% solution of citric, tartaric, acetic or hydrochloric acids.
Workers must be aware of basic safety regulations. At the place of work you should have first aid kits with a set of emergency medical supplies.
Each shift must have people who know how to provide first aid.
Bases consist of positively charged metal ions and hydroxide ions OH-. Alkalis are bases that are highly soluble in water.
Information about solubility in water can be taken from the solubility table. P – soluble bases, that is, alkalis, m – slightly soluble, n – insoluble, the line “–” means that such a base does not exist.
Under normal conditions they are solids. They look like white powders that easily absorb moisture. Requires storage in thick glass jars with a wide neck or plastic containers.
Getting grounds
Alkali is formed as a result of the reaction of metal and water with a large release of heat.
2Na + 2H2O>2NaOH + H2
CaO + H2O>Ca(OH)2.
Sodium and potassium hydroxides are formed when a solution is exposed to electric current:
KCl + 2H2O>2KOH + H2 + Cl2.
Properties of bases
Alkalis react
1. With acid oxides:
2KOH+SO3>K2SO4+H2O.
Alkalis are capable of dissolving the oxide film of aluminum (amphoteric oxide):
2. With acids:
NaOH+HCl>NaCl+HOH.
You can determine whether there is any alkali left by adding 1-2 drops of phenolphthalein solution. The alkali has reacted completely if the crimson color of the solution does not appear.
The reaction between a base and an acid is a neutralization reaction. Such reactions are often used to purify industrial wastewater from alkalis and acids. The products of such reactions are salts, which are safer for the environment. Neutralization of wastewater from various industries is very effective and cost-effective.
3. With salts. These are exchange reactions. Occur in solution, and the original salt must be water-soluble. And the resulting substance is insoluble:
2NaOH+Mn(NO3)2=Mn(OH)2v+2NaNO3
4. With halogens.
In the cold: Cl2 + 2NaOH = NaClO+NaCl+H2O.
When heated: 3Cl2+6NaOH = NaClO3+5NaCl+3H2O.
Only sodium and potassium hydroxides can be melted (the melting points of the compounds are 322° and 405°, respectively).
Safety when working with alkalis
Chemical burns caused by alkalis, including caustic soda and caustic potassium, are much more dangerous than chemical burns from acids. The burn is made worse if a piece of the crystalline substance sticks to the skin.
Alkalis can corrode many materials, cause serious burns on the skin and mucous membranes, and damage the eyes. Therefore, sodium hydroxide is called “caustic soda”, and potassium hydroxide is called “caustic potash”. When working with alkalis and their solutions, you must be careful. If the alkali solution gets on your skin, you should immediately wash it off with plenty of water. Then treat this area with a weak solution of acetic or boric acid. And rinse again with water.
What kind of substance is “ammonia”?
The liquid called “ammonia” is an aqueous solution of ammonia gas NH3. It is used as a medicine. Ammonia contains the base NH4OH (ammonium hydroxide). Formed as a result of the reaction:
NH3+H2O- NH4OH.
A small amount of dissolved ammonia interacts and at the same time decomposes into the original substances, as indicated by the “-” sign in the equation. Ammonium hydroxide, like alkalis, changes the color of the indicator and interacts with acidic oxides, acids and salts.
2NH4OH+СО2>(NH4)2СО3+H2O
NH4OH+HCl>NH4Cl+H2O
NH4OH+Pb(NO3)2>Pb(OH)2v+2NH4NO3.
Application of grounds
Ammonia is used not only to bring a person to consciousness. With its help, you can perfectly wash windows using 1 tablespoon of the drug per 1 liter of water. Then you need to wipe the surface with paper towels.
If you mix 1 part ammonia with 1 part vinegar, and then wipe the surface of the iron with the resulting solution, it will become clean. But don’t think that you will get an instant effect. The surface must be rubbed gently.
First of all, calcium and sodium hydroxides are widely used. Slaked lime is calcium hydroxide Ca(OH)2. It is used as a binding material in construction. Mix with sand and water. The resulting mixture is applied to the brick and the walls are plastered. As a result of the interaction of the base with carbon dioxide and silicon (IV) oxide, the mixture hardens. Lime is capable of absorbing acidic gases. It can also absorb toxic substances, so for the health of the residents, whitening the room is preferable to painting.
Calcium hydroxide is also used in the sugar industry, agriculture, in the manufacture of toothpastes, and in the production of many substances.
Sodium hydroxide (caustic soda) is used in the production of soap in the reaction of alkali with fat, in the manufacture of medicines, in the leather industry, and for oil purification. Caustic soda is used to clean oil stains. The well-known “Mole” for pipes is a sodium hydroxide solution that can dissolve fats and even hair.
Alkalis corrode glass and porcelain. Dissolves proteins.
They are used in medicine as antiseptics, irritants and cauterizing drugs. For diseases of the digestive system, alkaline mineral waters have a healing effect. Effective in the treatment of gout, stomatitis, and in the treatment of diseases of the respiratory system. They are a diuretic. Neutralizes acid poisoning.
The participation of alkalis in the production of rubber, artificial fiber, dyes, cleaning of metal objects, and processing of wooden surfaces is also important. They are a refrigerant for refrigeration units. Used in agriculture, light industry and metallurgy.
Alkaline foods
There are sour, alkaline and neutral foods. Alkaline foods include greens, turnips, cucumbers, horseradish, celery, lemons, beets, carrots, cabbage, citrus fruits, currants, grapes, cherries, dried fruits, potatoes, peppers, tomatoes, garlic.
It is noteworthy that neutral products contain both acids and alkalis. This is vegetable oil.
Interestingly, milk is an alkaline product. But warm or boiled milk is a sour product.
Alkalis are actively used by humans. In this case, you should remember and be sure to follow the safety rules.
