Chemistry is a science that studies various reactions occurring in nature, as well as the interaction of some compounds with others. The main substances here are acids and alkalis, the reactions between which are usually called neutralization. They lead to the formation of a water-soluble s alt.
What is lye
Hydroxides of alkaline (metals of the first group of the main (A) subgroup in the periodic table of chemical elements of D. I. Mendeleev) and alkaline earth (metals of the second group of the main (A) subgroup, including calcium) metals that violently interact with water and dissolve completely in it, are called alkalis. Since they are able to destroy organic material (leather, wood, paper), they are called caustic. For example, potassium hydroxide (KOH) is caustic potash, barium (Ba(OH)2) is caustic barium, and so on.
Physical properties of strong bases
Based on the definition of what an alkali is, we can add that these hydroxides are also solid hygroscopic (capable of absorbing vapors from the airwater) white substance. The strongest alkalis are cesium hydroxides CsOH and radium Ra(OH)2. Alkali reactions are most often accompanied by the release of heat (exothermic). Also, the physical properties of such bases include their ability to dissolve in some organic compounds, for example, in alcohols: methanol and ethanol.
Chemical properties
Solutions of alkalis are capable of entering into various reactions.
Strong bases have the ability to interact with acidic and amphoteric oxides:
- KOH + SO3=K2SO4 + H2O (SO3 is an acidic oxide);
- 2KOH + Al2O3=2KAlO2 + H2O (fusion reaction, takes place when heated, where Al2O3 is an amphoteric oxide);
- 2KOH + Al2O3 + 3H2O=2K[Al(OH)4] (the reaction proceeds with the formation of a soluble complex s alt - potassium tetrahydroxoaluminate).
When reacting with amphoteric metals (Zn, Al and others), the formation of both a melt and the corresponding complex s alt is also possible. Moreover, both reactions are accompanied by the evolution of gaseous hydrogen:
- 2KOH + 2Al=2KAlO2 + H2;
- 2KOH + 2Al + 6H2O=2K[Al(OH)4] + 3H2.
Alkalis are also able to react with s alts, resulting in the formation of another base and another s alt. The condition for the reaction to proceed is that, as a result, one of the formed substances must be insoluble in water:
NaOH + CuSO4=Na2SO4 + Cu(OH)2.
As mentioned earlier, alkalis and acids enter intoneutralization reaction, s alt and water are formed:
NaOH + HCl=NaCl + H2O.
Alkalis react with other bases only if they are hydroxides of amphoteric metals:
NaOH + Al(OH)3=Na[Al(OH)4].
Some of them can interact with many organic substances: esters, amides, polyhydric alcohols:
2C2H6O2 + 2NaOH=C2H4O2Na2 + 2H2O (the reaction product is sodium alkoxide).
How strong bottoms are made
Alkalis are obtained in various ways, both in industry and in laboratories.
In the industrial industry, there are several methods for obtaining alkalis: pyrolysis, lime, ferrite, electrolysis, which is divided into diaphragm, membrane and mercury methods on liquid and solid cathodes.
This is the electrolysis of solutions of sodium and potassium chlorides, after which chlorine and hydrogen are released at the anode and cathode, and the corresponding hydroxides are obtained:
- 2NaCl + 2H2O=H2 + Cl2 + 2NaOH;
- 2KCl + 2H2O=H2 + Cl2 + 2KOH.
When pyrolysis at 1000 degrees, the formation of sodium oxide occurs at the first stage:
Na2CO3=Na2O + CO2.
At the second stage, the resulting cooled oxide is dissolved in water, as a result of which the necessary alkali is obtained:
Na2O + H2O=2NaOH.
Laboratories also use electrolysis. Alkalis can also be obtained by exposing the corresponding metals to water or by reacting s alts of these metals with other bases, as a result of whichthe necessary alkali is obtained and the second product of the reaction, insoluble in water, is s alt.
When cesium and water interact, cesium hydroxide is obtained and hydrogen is released (the reaction proceeds even at a temperature of -120 degrees):
2Cs + 2H2O=2CsOH + H2.
As a result of the action of water on lithium oxide, alkali is obtained:
Li2O + 2H2O=2LiOH + H2.
Application
Based on the very definition of what alkali is, one can understand that they are widely used not only in industry, but also in everyday life:
- Disinfection of ponds for fishing.
- As a fertilizer.
- In pharmaceuticals.
- In paper production.
- Production of synthetic rubber.
- Obtaining soap and detergents.
- Electrolyte components in alkaline batteries.
- Carbon dioxide absorber (lithium hydroxide).
- Production of lubricants.
- Dyes in food production (food additives).
- Battery electrolytes (potassium hydroxide).
- Cleaning sewer pipes and sinks from food blockages.
- Acid neutralization.
- Catalysts in chemical industries.
- Chemical processing of photos.
Precautions
It becomes obvious that alkalis such as hydroxides of sodium, lithium, potassium, cesium and others can severely damage and burn the skin and mucous membranes of the eyes, even if the smallest particles of the compound get there. To prevent thisit is necessary to wear goggles, rubber gloves, and overalls that are treated with special substances that do not allow the material to interact with alkalis.
