Characteristics of aluminum. Aluminum: general characteristic

Each chemical element can be considered from the point of view of three sciences: physics, chemistry and biology. And in this article we will try to give the characteristics of aluminum as accurately as possible. This is a chemical element located in the third group and the third period, according to the periodic table. Aluminum is a metal that has an average chemical activity. Also in its compounds one can observe amphoteric properties. The atomic mass of aluminum is twenty-six grams per mole.

Physical characteristics of aluminum

Under normal conditions, it is a solid. The aluminum formula is very simple. It consists of atoms (do not combine into molecules), which are lined up with a crystal lattice into a solid substance. The color of aluminum is silvery white. In addition, it has a metallic luster, like all other substances in this group. The color of aluminum used in industry can be different due to the presence of impurities in the alloy. It's quite light metal. Its density is 2.7 g / cm3, that is, it is approximately three times lighter than iron. In this he can yield only to magnesium, which is even lighter than the metal in question. The hardness of aluminum is quite low. In it, it is inferior to most metals. The hardness of aluminum is only two on the Mohs scale. Therefore, to strengthen it, alloys based on this metal are added more solid.

Melting of aluminum occurs at a temperature of only 660 degrees Celsius. And it boils when heated to a temperature of two thousand four hundred and fifty-two degrees Celsius. It is very ductile and low-melting metal. This is not the end of the physical characteristics of aluminum. I would also like to note that this metal has the best electrical conductivity after copper and silver.

Prevalence in nature

Aluminum, the technical characteristics of which we have just considered, are often found in the environment. It can be observed in many minerals. Element aluminum - the fourth among all in the prevalence in nature. Its mass fraction in the earth's crust is almost nine percent. The main minerals, which contain its atoms, are bauxite, corundum, cryolite. The first is a rock that consists of oxides of iron, silicon and the metal in question, and water molecules are also present in the structure. It has a non-uniform coloration: fragments of gray, reddish-brown and other colors, which depend on the presence of various impurities. From thirty to sixty percent of this breed is aluminum, a photo of which can be seen above. In addition, corundum is a very common mineral in nature.

This is aluminum oxide. Its chemical formula is Al2O3. It can have a red, yellow, blue or brown color. Its hardness on the Mohs scale is nine units. To varieties of corundum are all known sapphires and rubies, leucosapphires, as well as padparadzha (yellow sapphire).

Cryolite is a mineral with a more complex chemical formula. It consists of aluminum and sodium fluorides - AlF3 • 3NaF. It looks like a colorless or grayish stone, with a low hardness - only three on the Mohs scale. In the modern world it is synthesized artificially in the laboratory. It is used in metallurgy.

Also, aluminum can be found in nature in clays, the main components of which are the oxides of silicon and the metal in question, associated with water molecules. In addition, this chemical element can be observed in the composition of nephelines, the chemical formula of which is as follows: KNa3 [AlSiO4] 4.

Receiving

The characteristics of aluminum include consideration of the methods for its synthesis. There are several methods. The production of aluminum by the first method occurs in three stages. The last of these is the electrolysis procedure on the cathode and the coal anode. To carry out such a process, aluminum oxide is needed, as well as auxiliary substances such as cryolite (formula - Na3AlF6) and calcium fluoride (CaF2). In order for the decomposition of aluminum oxide dissolved in water to occur, it must be heated together with the molten cryolite and calcium fluoride to a temperature of at least nine hundred and fifty degrees Celsius, and then pass through these substances a current of eighty thousand amperes and a voltage of five- Eight volts. Thus, due to this process, aluminum will settle on the cathode, and oxygen molecules will accumulate at the anode, which in turn oxidizes the anode and turns it into carbon dioxide. Before carrying out this procedure, bauxite, in the form of which aluminum oxide is extracted, is pre-cleaned of impurities, and also the process of its dehydration takes place.

The production of aluminum by the method described above is very common in metallurgy. There is also a method invented in 1827 by F. Weller. It consists in the fact that aluminum can be obtained by chemical reaction between its chloride and potassium. Such a process can be carried out only by creating special conditions in the form of a very high temperature and vacuum. Thus, from one mole of chloride and the same volume of potassium, one mole of aluminum and three moles of potassium chloride can be obtained as a by-product. This reaction can be written in the form of the following equation: АІСІ3 + 3К = АІ + 3КСІ. This method has not gained much popularity in metallurgy.

Characterization of aluminum in terms of chemistry

As mentioned above, this is a simple substance that consists of atoms that are not combined into molecules. Similar structures form almost all metals. Aluminum has a sufficiently high chemical activity and strong reducing properties. The chemical characterization of aluminum begins with the description of its reactions with other simple substances, and further interactions with complex inorganic compounds will be described.

Aluminum and simple substances

These include, first of all, oxygen - the most common compound on the planet. Twenty one percent of it consists of the Earth's atmosphere. The reactions of this substance with any other are called oxidation, or combustion. It usually occurs at high temperatures. But in the case of aluminum, oxidation under normal conditions is possible - this is how the oxide film is formed. If the given metal is crushed, it will burn, allocating thus a considerable quantity of energy in the form of heat. To carry out the reaction between aluminum and oxygen, these components are required in a molar ratio of 4: 3, resulting in two parts of the oxide.

This chemical interaction is expressed as the following equation: 4AI + 3O2 = 2AIO3. Also possible are the reactions of aluminum with halogens, which include fluorine, iodine, bromine and chlorine. The names of these processes come from the names of the corresponding halogens: fluorination, iodination, bromination and chlorination. These are typical reactions of addition.

For an example, let's mention the interaction of aluminum with chlorine. This kind of process can happen only in the cold.

So, taking two moles of aluminum and three moles of chlorine, we get as a result two moles of chloride of the metal in question. The equation of this reaction is as follows: 2АІ + 3СІ = 2АІСІ3. In the same way, aluminum fluoride, its bromide and iodide can be obtained.

With sulfur, the substance in question reacts only when heated. To carry out the interaction between these two compounds, it is necessary to take them in molar proportions of two to three, and one part of aluminum sulphide is formed. The equation for the reaction is as follows: 2Al + 3S = Al2S3.

In addition, at high temperatures, aluminum interacts with carbon, forming carbide, and with nitrogen, forming a nitride. One can cite the following equations of chemical reactions: 4AI + 3C = AІ4C3; 2Al + N2 = 2AlN.

Interaction with complex substances

These include water, salts, acids, bases, oxides. With all these chemicals, aluminum reacts differently. Let's take a closer look at each case.

Reaction with water

With the most complex substance on Earth, aluminum reacts with heating. This occurs only in the case of a preliminary removal of the film from the oxide. As a result of the interaction, an amphoteric hydroxide is formed, and hydrogen is also released into the air. Taking two parts of aluminum and six parts of water, we get hydroxide and hydrogen in molar proportions of two to three. The equation of this reaction is written as follows: 2AI + 6H2O = 2AI (OH) 3 + 3H2.

Interaction with acids, bases and oxides

Like other active metals, aluminum is able to enter a substitution reaction. In this case, it can displace hydrogen from the acid or cation of a more passive metal from its salt. As a result of such interactions, an aluminum salt is formed, hydrogen is also released (in the case of an acid) or pure metal precipitates (one that is less active than the one under consideration). In the second case, the reducing properties that were mentioned above appear. An example is the interaction of aluminum with hydrochloric acid, in which aluminum chloride is formed and hydrogen is released into the air. This kind of reaction is expressed in the form of the following equation: 2AI + 6HCl = 2AІСІ3 + 3H2.

An example of the interaction of aluminum with a salt is its reaction with copper sulfate. Taking these two components, in the end we get aluminum sulphate and pure copper, which will fall out as a precipitate. With acids such as sulfuric and nitric, aluminum reacts in a peculiar way. For example, when aluminum is added to a dilute solution of nitrate in a molar ratio of eight parts to thirty, eight parts of the nitrate of the metal are formed, three parts of nitrogen oxide and fifteen of water. The equation of this reaction is written in this way: 8Al + 30HNO3 = 8Al (NO3) 3 + 3N2O + 15H2O. This process occurs only when there is a high temperature.

If you mix aluminum and a weak solution of sulphate acid in molar proportions of two to three, we get the sulfate of the metal in question and hydrogen in a ratio of one to three. That is, an ordinary substitution reaction will occur, as in the case of other acids. For clarity, we give the equation: 2Al + 3H2SO4 = Al2 (SO4) 3 + 3H2. However, with a concentrated solution of the same acid, everything is more complicated. Here, as in the case of nitrate, a by-product is formed, but not in the form of oxide, but in the form of sulfur, and water. If we take two components necessary to us in a molar ratio of two to four, then as a result we get one part of the salt of the metal and sulfur in question, and four - the water. This chemical interaction can be expressed by the following equation: 2Al + 4H2SO4 = Al2 (SO4) 3 + S + 4H2O. In addition, aluminum is able to react with alkali solutions. To carry out this chemical interaction, it is necessary to take two moles of the metal in question, as much sodium hydroxide or potassium hydroxide, as well as six moles of water. As a result, such substances as sodium tetrahydroxoaluminate or potassium, as well as hydrogen, are formed, which is released as a gas with a sharp odor in molar proportions of two to three. This chemical reaction can be represented as the following equation: 2AI + 2KOH + 6H2O = 2K [AI (OH) 4] + 3H2.

And the last thing to consider is the patterns of interaction of aluminum with certain oxides. The most common and used case is Beketov's reaction. It, as well as many other of the above, occurs only at high temperatures. So, to implement it, you need to take two moles of aluminum and one mole of ferrux oxide. As a result of the interaction of these two substances, we obtain alumina and free iron in an amount of one and two moles, respectively.

Use of the metal in question in industry

Note that the use of aluminum is very common. First of all, the aviation industry needs it. Along with magnesium alloys, alloys based on the metal under consideration are also used here. We can say that the average aircraft is 50% composed of aluminum alloys, and its engine by 25%. Also, the use of aluminum is carried out in the process of making wires and cables due to its excellent electrical conductivity. In addition, this metal and its alloys are widely used in the automotive industry. Of these materials there are hulls of cars, buses, trolleybuses, some trams, as well as cars of conventional and electric trains. It is also used for smaller scale purposes, for example, for the production of packaging for food and other products, utensils. In order to make a silvery paint, the powder of the metal in question is necessary. This paint is needed in order to protect the iron from corrosion. It can be said that aluminum is the second most frequently used metal in the industry after ferrum. His compounds and himself are often used in the chemical industry. This is due to the special chemical properties of aluminum, including its reducing properties and amphotericity of its compounds. The hydroxide of the chemical element in question is necessary for water purification. In addition, it is used in medicine in the production of vaccines. Also it can be found in some types of plastic and other materials.

Role in nature

As already mentioned above, aluminum is found in large quantities in the earth's crust. It is especially important for living organisms. Aluminum is involved in the regulation of growth processes, forms connective tissues, such as bone, ligament and others. Thanks to this microelement, the processes of tissue regeneration are carried out faster. Its shortage is characterized by the following symptoms: developmental and growth disorders in children, in adults - chronic fatigue, decreased efficiency, impaired coordination of movements, decreased rates of tissue regeneration, muscle weakness, especially in the limbs. Such a phenomenon can arise if you consume too few products with the content of a given microelement.

However, a more frequent problem is the excess of aluminum in the body. In addition, symptoms such as nervousness, depression, sleep disorders, memory loss, stress resistance, softening of the musculoskeletal system are often observed, which can lead to frequent fractures and sprains. With prolonged excess of aluminum in the body, there are often problems in the operation of almost every organ system.

To this phenomenon can lead a number of reasons. First of all, it is aluminum cookware. Scientists have long proven that the dishes made of the metal in question are not suitable for cooking in it, since at high temperature some aluminum is ingested, and as a consequence, you consume far more of this trace element than the body needs.

The second reason - the regular use of cosmetics with the content of the metal or its salts. Before using any product, you should carefully read its composition. Cosmetics are not an exception.

The third reason is taking drugs that contain a lot of aluminum, for a long time. And also improper use of vitamins and food additives, which include this microelement.

Now let's figure out which products contain aluminum in order to regulate your diet and organize the menu correctly. First of all, it is carrots, processed cheese, wheat, alum, potatoes. Of fruits, avocados and peaches are recommended. In addition, white cabbage, rice, many herbs are rich in aluminum. Also, the cations of the metal in question can be contained in drinking water. To avoid an increased or decreased aluminum content in the body (however, just like any other microelement), you need to carefully monitor your diet and try to make it as balanced as possible.