Aluminum- element of the 13th (III) group of the periodic table of chemical elements with atomic number 13. Denoted by the symbol Al. Belongs to the group of light metals. The most common metal and the third most abundant chemical element in the earth's crust (after oxygen and silicon).
Aluminium oxide Al2O3- distributed in nature as alumina, a white refractory powder, close to diamond in hardness.
Aluminum oxide is a natural compound that can be obtained from bauxite or from the thermal decomposition of aluminum hydroxides:
2Al(OH)3 = Al2O3 + 3H2O;
Al2O3 is an amphoteric oxide, chemically inert due to its strong crystal lattice. It does not dissolve in water, does not interact with solutions of acids and alkalis, and can only react with molten alkali.
At about 1000°C, it intensively interacts with alkalis and alkali metal carbonates to form aluminates:
Al2O3 + 2KOH = 2KAlO2 + H2O; Al2O3 + Na2CO3 = 2NaAlO2 + CO2.
Other forms of Al2O3 are more active and can react with solutions of acids and alkalis, α-Al2O3 reacts only with hot concentrated solutions: Al2O3 + 6HCl = 2AlCl3 + 3H2O;
The amphoteric properties of aluminum oxide appear when it interacts with acidic and basic oxides to form salts:
Al2O3 + 3SO3 = Al2(SO4)3 (basic properties), Al2O3 + Na2O = 2NaAlO2 (acidic properties).
Aluminum hydroxide, Al(OH)3- a combination of aluminum oxide and water. A white gelatinous substance, poorly soluble in water, has amphoteric properties. Obtained by reacting aluminum salts with aqueous solutions of alkali: AlCl3+3NaOH=Al(OH)3+3NaCl
Aluminum hydroxide is a typical amphoteric compound; freshly obtained hydroxide dissolves in acids and alkalis:
2Al(OH)3 + 6HCl = 2AlCl3 + 6H2O. Al(OH)3 + NaOH + 2H2O = Na.
When heated, it decomposes; the dehydration process is quite complex and can be schematically represented as follows:
Al(OH)3 = AlOOH + H2O. 2AlOOH = Al2O3 + H2O.
Aluminates - salts formed by the action of alkali on freshly precipitated aluminum hydroxide: Al(OH)3 + NaOH = Na (sodium tetrahydroxoaluminate)
Aluminates are also obtained by dissolving aluminum metal (or Al2O3) in alkalis: 2Al + 2NaOH + 6H2O = 2Na + 3H2
Hydroxoaluminates are formed by the interaction of Al(OH)3 with excess alkali: Al(OH)3 + NaOH (ex) = Na
Aluminum salts. Almost all aluminum salts can be obtained from aluminum hydroxide. Almost all aluminum salts are highly soluble in water; Aluminum phosphate is poorly soluble in water.
In solution, aluminum salts exhibit an acidic reaction. An example is the reversible effect of aluminum chloride with water:
AlCl3+3H2O«Al(OH)3+3HCl
Many aluminum salts are of practical importance. For example, anhydrous aluminum chloride AlCl3 is used in chemical practice as a catalyst in oil refining
Aluminum sulfate Al2(SO4)3 18H2O is used as a coagulant in the purification of tap water, as well as in paper production.
Double aluminum salts are widely used - alum KAl(SO4)2 12H2O, NaAl(SO4)2 12H2O, NH4Al(SO4)2 12H2O, etc. - they have strong astringent properties and are used in leather tanning, as well as in medical practice as a hemostatic agent.
Application- Due to its complex of properties, it is widely used in thermal equipment. - Aluminum and its alloys retain strength at ultra-low temperatures. Due to this, it is widely used in cryogenic technology. - Aluminum is an ideal material for the manufacture of mirrors. - In the production of building materials as a gas-forming agent. - Aluminization imparts corrosion and scale resistance to steel and other alloys. - Aluminum sulfide is used for the production of hydrogen sulfide. - Research is underway on development of foamed aluminum as an especially durable and lightweight material.
As a reducing agent- As a component of thermite, mixtures for aluminothermy - In pyrotechnics. - Aluminum is used to restore rare metals from their oxides or halides. (Aluminothermy)
Aluminothermy.- a method for producing metals, non-metals (as well as alloys) by reducing their oxides with metallic aluminum.
Aluminum hydroxide is a chemical substance that is a compound of aluminum oxide with water. It can exist in liquid and solid states. Liquid hydroxide is a jelly-like transparent substance that is very poorly soluble in water. Solid hydroxide is a white crystalline substance that has passive chemical properties and does not react with virtually any other element or compound.
Preparation of aluminum hydroxide
Aluminum hydroxide is produced through a chemical exchange reaction. To do this, use an aqueous solution of ammonia and some aluminum salt, most often aluminum chloride. In this way a liquid substance is obtained. If a solid hydroxide is required, carbon dioxide is passed through a dissolved sodium tetrahydroxodiaquaaluminate alkali. Many lovers of experiments are concerned with the question of how to obtain aluminum hydroxide at home? To do this, it is enough to purchase the necessary reagents and chemical glassware from a specialized store.
To obtain a solid substance, you will also need special equipment, so it is better to stick with the liquid version. When carrying out the reaction, it is necessary to use a well-ventilated area, since one of the by-products may be a gas or a substance with a strong odor, which can adversely affect human well-being and health. It is worth working in special protective gloves, since most acids cause chemical burns when they come into contact with the skin. It would also be a good idea to take care of eye protection in the form of special glasses. When starting any business, first of all you need to think about ensuring safety!
Freshly synthesized aluminum hydroxide reacts with most active acids and alkalis. That is why ammonia water is used to obtain it in order to preserve the formed substance in its pure form. When used to produce an acid or alkali, it is necessary to calculate the proportion of elements as accurately as possible, otherwise, if there is an excess, the resulting aluminum hydroxide interacts with the remnants of the unabsorbed base and completely dissolves in it. This is due to the high level of chemical activity of aluminum and its compounds.
Basically, aluminum hydroxide is obtained from bauxite ore, which has a high metal oxide content. The procedure allows you to quickly and relatively cheaply separate useful elements from waste rock. Reactions of aluminum hydroxide with acids lead to the reduction of salts and the formation of water, and with alkalis - to the production of complex hydroxoaluminum salts. Solid hydroxide is combined with solid alkalis by fusion to form meta-aluminates.
Basic properties of the substance
Physical properties of aluminum hydroxide: density - 2.423 grams per cubic centimeter, solubility level in water - low, color - white or transparent. The substance can exist in four polymorphic variants. When exposed to low temperatures, an alpha hydroxide called bayerite is formed. When exposed to heat, gamma hydroxide or gibbsite can be obtained. Both substances have a crystalline molecular lattice with hydrogen intermolecular bonding types. Two more modifications are also found - beta-hydroxide or nordstandrite and triclinic hibisite. The first is obtained by calcining bayerite or gibbsite. The second differs from other types in the triclinic, rather than monomorphic, structure of the crystal lattice.
Chemical properties of aluminum hydroxide: molar mass - 78 mol, in the liquid state it dissolves well in active acids and alkalis, decomposes when heated, has amphoteric properties. In industry, in the vast majority of cases, liquid hydroxide is used, since due to its high level of chemical activity, it is easy to process and does not require the use of catalysts or special reaction conditions.
The amphoteric nature of aluminum hydroxide is manifested in the duality of its nature. This means that under different conditions it can exhibit acidic or alkaline properties. When the hydroxide reacts as an alkali, a salt is formed in which aluminum is a positively charged cation. Acting as an acid, aluminum hydroxide also forms a salt at the exit. But in this case, the metal already plays the role of a negatively charged anion. The dual nature opens up wide possibilities for the use of this chemical compound. It is used in medicine for the manufacture of medications prescribed for disturbances in the acid-base balance in the body.
Aluminum hydroxide is included in vaccines as a substance that enhances the body's immune response to an irritant. The insolubility of aluminum hydroxide precipitate in water allows the substance to be used for water treatment purposes. The chemical compound is a very strong adsorbent, which allows you to remove a large number of harmful elements from water.
Industrial Applications
The use of hydroxide in industry is associated with the production of pure aluminum. The technological process begins with the processing of ore containing aluminum oxide, which upon completion of the process turns into hydroxide. The yield of this reaction is high enough that when completed, what is left is essentially bare rock. Next, the decomposition operation of aluminum hydroxide is carried out.
The procedure does not require special conditions, since the substance decomposes well when heated to temperatures above 180 degrees Celsius. This step allows the aluminum oxide to be isolated. This compound is a base or auxiliary material for the manufacture of a large number of industrial and household products. If it is necessary to obtain pure aluminum, the electrolysis process is used with the addition of sodium cryolite to the solution. The catalyst takes oxygen from the oxide, and pure aluminum settles on the cathode.
Aluminum is an amphoteric metal. The electronic configuration of the aluminum atom is 1s 2 2s 2 2p 6 3s 2 3p 1. Thus, it has three valence electrons on its outer electron layer: 2 on the 3s and 1 on the 3p sublevel. Due to this structure, it is characterized by reactions as a result of which the aluminum atom loses three electrons from the outer level and acquires an oxidation state of +3. Aluminum is a highly reactive metal and exhibits very strong reducing properties.
Interaction of aluminum with simple substances
with oxygen
When absolutely pure aluminum comes into contact with air, aluminum atoms located in the surface layer instantly interact with oxygen in the air and form a thin, tens of atomic layers thick, durable oxide film of the composition Al 2 O 3, which protects aluminum from further oxidation. It is also impossible to oxidize large samples of aluminum even at very high temperatures. However, fine aluminum powder burns quite easily in a burner flame:
4Al + 3O 2 = 2Al 2 O 3
with halogens
Aluminum reacts very vigorously with all halogens. Thus, the reaction between mixed aluminum and iodine powders occurs already at room temperature after adding a drop of water as a catalyst. Equation for the interaction of iodine with aluminum:
2Al + 3I 2 =2AlI 3
Aluminum also reacts with bromine, which is a dark brown liquid, without heating. Simply add a sample of aluminum to liquid bromine: a violent reaction immediately begins, releasing a large amount of heat and light:
2Al + 3Br 2 = 2AlBr 3
The reaction between aluminum and chlorine occurs when heated aluminum foil or fine aluminum powder is added to a flask filled with chlorine. Aluminum burns effectively in chlorine according to the equation:
2Al + 3Cl 2 = 2AlCl 3
with sulfur
When heated to 150-200 o C or after igniting a mixture of powdered aluminum and sulfur, an intense exothermic reaction begins between them with the release of light:
— sulfide aluminum
with nitrogen
When aluminum reacts with nitrogen at a temperature of about 800 o C, aluminum nitride is formed:
with carbon
At a temperature of about 2000 o C, aluminum reacts with carbon and forms aluminum carbide (methanide), containing carbon in the -4 oxidation state, as in methane.
Interaction of aluminum with complex substances
with water
As mentioned above, a stable and durable oxide film of Al 2 O 3 prevents aluminum from oxidizing in air. The same protective oxide film makes aluminum inert towards water. When removing the protective oxide film from the surface by methods such as treatment with aqueous solutions of alkali, ammonium chloride or mercury salts (amalgiation), aluminum begins to react vigorously with water to form aluminum hydroxide and hydrogen gas:
with metal oxides
After igniting a mixture of aluminum with oxides of less active metals (to the right of aluminum in the activity series), an extremely violent, highly exothermic reaction begins. Thus, in the case of interaction of aluminum with iron (III) oxide, a temperature of 2500-3000 o C develops. As a result of this reaction, high-purity molten iron is formed:
2AI + Fe 2 O 3 = 2Fe + Al 2 O 3
This method of obtaining metals from their oxides by reduction with aluminum is called aluminothermy or aluminothermy.
with non-oxidizing acids
The interaction of aluminum with non-oxidizing acids, i.e. with almost all acids, except concentrated sulfuric and nitric acids, leads to the formation of an aluminum salt of the corresponding acid and hydrogen gas:
a) 2Al + 3H 2 SO 4 (diluted) = Al 2 (SO 4) 3 + 3H 2
2Al 0 + 6H + = 2Al 3+ + 3H 2 0 ;
b) 2AI + 6HCl = 2AICl3 + 3H2
with oxidizing acids
-concentrated sulfuric acid
The interaction of aluminum with concentrated sulfuric acid under normal conditions and at low temperatures does not occur due to an effect called passivation. When heated, the reaction is possible and leads to the formation of aluminum sulfate, water and hydrogen sulfide, which is formed as a result of the reduction of sulfur, which is part of sulfuric acid:
Such a deep reduction of sulfur from the oxidation state +6 (in H 2 SO 4) to the oxidation state -2 (in H 2 S) occurs due to the very high reducing ability of aluminum.
- concentrated nitric acid
Under normal conditions, concentrated nitric acid also passivates aluminum, which makes it possible to store it in aluminum containers. Just as in the case of concentrated sulfuric acid, the interaction of aluminum with concentrated nitric acid becomes possible with strong heating, and the reaction predominantly occurs:
- dilute nitric acid
The interaction of aluminum with diluted nitric acid compared to concentrated nitric acid leads to products of deeper nitrogen reduction. Instead of NO, depending on the degree of dilution, N 2 O and NH 4 NO 3 can be formed:
8Al + 30HNO 3(dil.) = 8Al(NO 3) 3 +3N 2 O + 15H 2 O
8Al + 30HNO 3(pure dilute) = 8Al(NO 3) 3 + 3NH 4 NO 3 + 9H 2 O
with alkalis
Aluminum reacts both with aqueous solutions of alkalis:
2Al + 2NaOH + 6H 2 O = 2Na + 3H 2
and with pure alkalis during fusion:
In both cases, the reaction begins with the dissolution of the protective film of aluminum oxide:
Al 2 O 3 + 2NaOH + 3H 2 O = 2Na
Al 2 O 3 + 2NaOH = 2NaAlO 2 + H 2 O
In the case of an aqueous solution, aluminum, cleared of the protective oxide film, begins to react with water according to the equation:
2Al + 6H 2 O = 2Al(OH) 3 + 3H 2
The resulting aluminum hydroxide, being amphoteric, reacts with an aqueous solution of sodium hydroxide to form soluble sodium tetrahydroxoaluminate:
Al(OH) 3 + NaOH = Na
The electronic configuration of the external level of aluminum is ... 3s 2 3p 1.
In the excited state, one of the s-electrons goes to a free cell of the p-sublevel; this state corresponds to valence III and oxidation state +3.
In the outer electron layer of the aluminum atom there are free d-sublevels. Due to this, its coordination number in compounds can be not only 4 ([A1(OH) 4 ] -), but also 6 – ([A1(OH) 6 ] 3-).
Being in nature
The most abundant metal in the earth's crust, the total aluminum content in the earth's crust is 8.8%.
It is not found in free form in nature.
The most important natural compounds are aluminosilicates:
white clay Al 2 O 3 ∙ 2SiO 2 ∙ 2H 2 O, feldspar K 2 O ∙ Al 2 O 3 ∙ 6SiO 2, mica K 2 O ∙ Al 2 O 3 ∙ 6SiO 2 ∙ H 2 O
Of the other natural forms of aluminum, the most important are bauxite A1 2 Oz ∙ nH 2 O, the minerals corundum A1 2 Oz and cryolite A1F3 ∙ 3NaF.
Receipt
Currently, in industry, aluminum is produced by electrolysis of aluminum oxide A1 2 O 3 in molten cryolite.
The electrolysis process ultimately comes down to the decomposition of A1 2 Oz by electric current
2А1 2 Oz = 4А1 + 3О 2 (950 0 C, А1Fз ∙3NaF, electric current)
Liquid aluminum is released at the cathode:
A1 3+ + 3e-= Al 0
Oxygen is released at the anode.
Physical properties
A lightweight, silver-white, ductile metal that conducts electricity and heat well.
In air, aluminum is coated with a thin (0.00001 mm) but very dense oxide film, which protects the metal from further oxidation and gives it a matte appearance.
Aluminum is easily drawn into wire and rolled into thin sheets. Aluminum foil (0.005 mm thick) is used in the food and pharmaceutical industries for packaging products and drugs.
Chemical properties
Aluminum is a very active metal, slightly inferior in activity to the elements of the early period - sodium and magnesium.
1. aluminum easily combines with oxygen at room temperature, and an oxide film (A1 2 O 3 layer) is formed on the surface of the aluminum. This film is very thin (≈ 10 -5 mm), but durable. It protects the aluminum from further oxidation and is therefore called a protective film
4Al + 3O 2 = 2Al 2 O 3
2. upon interaction with halogens, halides are formed:
interaction with chlorine and bromine occurs already at ordinary temperatures, with iodine and sulfur - when heated.
2Al + 3Cl 2 = 2AlCl 3
2Al + 3S= Al 2 S 3
3. At very high temperatures, aluminum also directly combines with nitrogen and carbon.
2Al + N 2 = 2AlN aluminum nitride
4Al + 3C = Al 4 C 3 aluminum carbide
Aluminum does not interact with hydrogen.
4. Aluminum is quite resistant to water. But if the protective effect of the oxide film is removed mechanically or by amalgamation, a vigorous reaction occurs:
2Al + 6H 2 O = 2Al(OH) 3 + 3H 2
5. interaction of aluminum with acids
With disag. aluminum reacts with acids (HCl, H 2 SO 4) to form hydrogen.
2Al + 6HCl = 2AlCl3 + 3H2
In the cold, aluminum does not react with concentrated sulfuric and nitric acid.
Interacts with conc. sulfuric acid when heated
8Al + 15H 2 SO 4 = 4Al 2 (SO 4) 3 + 3H 2 S + 12H 2 O
Aluminum reacts with dilute nitric acid to form NO
Al + 4HNO 3 = Al(NO 3) 3 + NO +2H 2 O
6. interaction of aluminum with alkalis
Aluminum, like other metals that form amphoteric oxides and hydroxides, react with alkali solutions.
Aluminum under normal conditions, as already noted, is covered with a protective film A1 2 O 3. When aluminum is exposed to aqueous solutions of alkalis, the layer of aluminum oxide A1 2 O 3 dissolves, and aluminates are formed - salts containing aluminum as part of the anion:
A1 2 O 3 + 2NaOH + 3H 2 O = 2Na
Aluminum, devoid of a protective film, interacts with water, displacing hydrogen from it
2Al + 6H 2 O = 2Al (OH) 3 + 3H 2
The resulting aluminum hydroxide reacts with excess alkali to form tetrahydroxoaluminate
Al(OH) 3 + NaOH = Na
The overall equation for the dissolution of aluminum in an aqueous alkali solution:
2Al + 2NaOH + 6H 2 O = 2Na+ 3H 2
Aluminum oxide A1 2 O 3
White solid, insoluble in water, melting point 2050 0 C.
Natural A1 2 O 3 - mineral corundum. Transparent colored corundum crystals - red ruby - contains an admixture of chromium - and blue sapphire - an admixture of titanium and iron - precious stones. They are also obtained artificially and used for technical purposes, for example, for the manufacture of parts for precision instruments, watch stones, etc.
Chemical properties
Aluminum oxide exhibits amphoteric properties
1. interaction with acids
A1 2 O 3 + 6HCl = 2AlCl 3 + 3H 2 O
2. interaction with alkalis
A1 2 O 3 + 2NaOH – 2NaAlO 2 + H 2 O
Al 2 O 3 + 2NaOH + 5H 2 O = 2Na
3. When a mixture of the oxide of the corresponding metal with aluminum powder is heated, a violent reaction occurs, leading to the release of free metal from the taken oxide. The reduction method using Al (aluminothermy) is often used to obtain a number of elements (Cr, Mn, V, W, etc.) in a free state
2A1 + WO 3 = A1 2 Oz + W
4. interaction with salts that have a highly alkaline environment due to hydrolysis
Al 2 O 3 + Na 2 CO 3 = 2 NaAlO 2 + CO 2
Aluminum hydroxide A1(OH) 3
A1(OH) 3 is a voluminous gelatinous white precipitate, practically insoluble in water, but easily soluble in acids and strong alkalis. It therefore has an amphoteric character.
Aluminum hydroxide is obtained by the exchange of soluble aluminum salts with alkalis
AlCl 3 + 3NaOH = Al(OH) 3 ↓ + 3NaCl
Al 3+ + 3OH - = Al(OH) 3 ↓
This reaction can be used as a qualitative reaction for the Al 3+ ion
Chemical properties
1. interaction with acids
Al(OH) 3 + 3HCl = 2AlCl 3 + 3H 2 O
2. upon interaction with strong alkalis, the corresponding aluminates are formed:
NaOH + A1(OH)3 = Na
3. thermal decomposition
2Al(OH) 3 = Al 2 O 3 + 3H 2 O
Aluminum salts undergo hydrolysis by cation, the medium is acidic (pH< 7)
Al 3+ + H + OH - ↔ AlOH 2+ + H +
Al(NO 3) 3 + H 2 O↔ AlOH(NO 3) 2 + HNO 3
Soluble aluminum salts and weak acids undergo complete (irreversible hydrolysis)
Al 2 S 3 + 3H 2 O = 2Al(OH) 3 + 3H 2 S
Application in medicine and national economy of aluminum and its compounds.
The lightness of aluminum and its alloys and greater resistance to air and water determine their use in mechanical engineering and aircraft manufacturing. In its pure metal form, aluminum is used to make electrical wires.
Aluminum foil (0.005 mm thick) is used in the food and pharmaceutical industries for packaging products and drugs.
Aluminum oxide Al 2 O 3 - included in some antacids (for example, Almagel), used for increased acidity of gastric juice.
KAl(SO 4) 3 12H 2 O - potassium alum is used in medicine for the treatment of skin diseases, as a hemostatic agent. It is also used as a tannin in the leather industry.
(CH 3 COO) 3 Al - Burov's liquid - 8% solution of aluminum acetate has an astringent and anti-inflammatory effect, and in high concentrations it has moderate antiseptic properties. It is used in diluted form for rinsing, lotions, and for inflammatory diseases of the skin and mucous membranes.
AlCl 3 - used as a catalyst in organic synthesis.
Al 2 (SO 4) 3 · 18 H 2 0 – used for water purification.
Test questions for consolidation:
1. Name the highest valency oxidation state of elements of group III A. Explain in terms of atomic structure.
2.Name the most important boron compounds. What is the qualitative reaction to borate ion?
3. What chemical properties do aluminum oxide and hydroxide have?
Mandatory
Pustovalova L.M., Nikanorova I.E. . Inorganic chemistry. Rostov-on-Don. Phoenix. 2005. –352 p. Ch. 2.1 p. 283-294
Additional
1. Akhmetov N.S. General and inorganic chemistry. M.: Higher School, 2009.- 368 p.
2. Glinka N.L. General chemistry. KnoRus, 2009.-436 p.
3. Erokhin Yu.M. Chemistry. Textbook for students. Professional education environment - M.: Academy, 2006. - 384 p.
Electronic resources
1. Open chemistry: a complete interactive chemistry course for schools, lyceums, gymnasiums, colleges, students. technical universities: version 2.5-M.: Physikon, 2006. Electronic optical disk CD-ROM
2. .1C: Tutor - Chemistry, for applicants, high school students and teachers, JSC "1C", 1998-2005. Electronic optical disc CD-ROM
3. Chemistry. Fundamentals of theoretical chemistry. [Electronic resource]. URL: http://chemistry.narod.ru/himiya/default.html
4. Electronic library of educational materials in chemistry [Electronic resource]. URL: http://www.chem.msu.su/rus/elibrary/
One of the most widely used substances in industry is aluminum hydroxide. This article will talk about it.
What is hydroxide?
This is a chemical compound that is formed when an oxide reacts with water. There are three types of them: acidic, basic and amphoteric. The first and second are divided into groups depending on their chemical activity, properties and formula.
What are amphoteric substances?
Oxides and hydroxides can be amphoteric. These are substances that tend to exhibit both acidic and basic properties, depending on the reaction conditions, reagents used, etc. Amphoteric oxides include two types of iron oxide, oxide of manganese, lead, beryllium, zinc, and aluminum . The latter, by the way, is most often obtained from its hydroxide. Amphoteric hydroxides include beryllium hydroxide, iron hydroxide, and aluminum hydroxide, which we will consider today in our article.
Physical properties of aluminum hydroxide
This chemical compound is a white solid. It does not dissolve in water.
Aluminum hydroxide - chemical properties
As mentioned above, this is the most striking representative of the group of amphoteric hydroxides. Depending on the reaction conditions, it can exhibit both basic and acidic properties. This substance can dissolve in acids, resulting in the formation of salt and water.
For example, if you mix it with perchloric acid in equal quantities, you will get aluminum chloride with water also in equal proportions. Also, another substance that aluminum hydroxide reacts with is sodium hydroxide. This is a typical basic hydroxide. If you mix the substance in question and a solution of sodium hydroxide in equal quantities, you get a compound called sodium tetrahydroxyaluminate. Its chemical structure contains a sodium atom, an aluminum atom, four atoms of oxygen and hydrogen. However, when these substances are fused, the reaction proceeds somewhat differently, and it is no longer this compound that is formed. As a result of this process, it is possible to obtain sodium metaaluminate (its formula includes one atom of sodium and aluminum and two atoms of oxygen) with water in equal proportions, provided that the same amount of dry sodium and aluminum hydroxides is mixed and exposed to high temperature. If you mix it with sodium hydroxide in other proportions, you can get sodium hexahydroxyaluminate, which contains three sodium atoms, one aluminum atom and six each of oxygen and hydrogen. In order for this substance to be formed, you need to mix the substance in question and a solution of sodium hydroxide in proportions of 1:3, respectively. Using the principle described above, compounds called potassium tetrahydroxoaluminate and potassium hexahydroxoaluminate can be obtained. Also, the substance in question is susceptible to decomposition when exposed to very high temperatures. As a result of this kind of chemical reaction, aluminum oxide, which is also amphoteric, and water are formed. If you take 200 g of hydroxide and heat it, you get 50 g of oxide and 150 g of water. In addition to the peculiar chemical properties, this substance also exhibits properties common to all hydroxides. It interacts with metal salts, which have lower chemical activity than aluminum. For example, we can consider the reaction between it and copper chloride, for which you need to take them in a ratio of 2:3. In this case, water-soluble aluminum chloride and a precipitate in the form of cuprum hydroxide will be released in proportions of 2:3. The substance in question also reacts with oxides of similar metals; for example, we can take a compound of the same copper. To carry out the reaction, you will need aluminum hydroxide and cuprum oxide in a ratio of 2:3, resulting in aluminum oxide and copper hydroxide. Other amphoteric hydroxides, such as iron or beryllium hydroxide, also have the properties described above.
What is sodium hydroxide?
As can be seen above, there are many variations in the chemical reactions of aluminum hydroxide with sodium hydroxide. What kind of substance is this? It is a typical basic hydroxide, that is, a reactive, water-soluble base. It has all the chemical properties that are characteristic of basic hydroxides.
That is, it can dissolve in acids, for example, when mixing sodium hydroxide with perchloric acid in equal quantities, you can get table salt (sodium chloride) and water in a 1:1 ratio. This hydroxide also reacts with metal salts, which have lower chemical activity than sodium, and their oxides. In the first case, a standard exchange reaction occurs. When, for example, silver chloride is added to it, sodium chloride and silver hydroxide are formed, which precipitate (the exchange reaction is feasible only if one of the substances resulting from it is a precipitate, gas or water). When adding, for example, zinc oxide to sodium hydroxide, we obtain the latter's hydroxide and water. However, much more specific are the reactions of this hydroxide AlOH, which were described above.
Preparation of AlOH
Now that we have already looked at its basic chemical properties, we can talk about how it is mined. The main way to obtain this substance is to carry out a chemical reaction between an aluminum salt and sodium hydroxide (potassium hydroxide can also be used).
With this kind of reaction, AlOH itself is formed, which precipitates into a white precipitate, as well as a new salt. For example, if you take aluminum chloride and add three times more potassium hydroxide to it, the resulting substances will be the chemical compound discussed in the article and three times more potassium chloride. There is also a method for producing AlOH, which involves carrying out a chemical reaction between a solution of an aluminum salt and a carbonate of the base metal; let’s take sodium as an example. To obtain aluminum hydroxide, kitchen salt and carbon dioxide in a ratio of 2:6:3, you need to mix aluminum chloride, sodium carbonate (soda) and water in a ratio of 2:3:3.
Where is aluminum hydroxide used?
Aluminum hydroxide finds its use in medicine.
Due to its ability to neutralize acids, preparations containing it are recommended for heartburn. It is also prescribed for ulcers, acute and chronic inflammatory processes of the intestines. In addition, aluminum hydroxide is used in the manufacture of elastomers. It is also widely used in the chemical industry for the synthesis of aluminum oxide and sodium aluminates - these processes were discussed above. In addition, it is often used when purifying water from contaminants. This substance is also widely used in the manufacture of cosmetics.
Where are the substances that can be obtained with its help used?
Aluminum oxide, which can be obtained due to the thermal decomposition of hydroxide, is used in the manufacture of ceramics and is used as a catalyst for carrying out various chemical reactions. Sodium tetrahydroxyaluminate finds its use in fabric dyeing technology.