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Oxides- OXIDES, compounds chemical elements(except fluorine) with oxygen. When interacting with water, they form bases (basic oxides) or acids (acidic oxides); many oxides are amphoteric. Most oxides under normal conditions solids,… … Illustrated Encyclopedic Dictionary
Oxide (oxide, oxide) is a binary compound of a chemical element with oxygen in the oxidation state −2, in which the oxygen itself is bonded only to the less electronegative element. The chemical element oxygen is second in electronegativity... ... Wikipedia
Metal oxides- These are compounds of metals with oxygen. Many of them can combine with one or more water molecules to form hydroxides. Most oxides are basic because their hydroxides behave like bases. However, some... ... Official terminology
oxides- The combination of a chemical element with oxygen. According to their chemical properties, all oxides are divided into salt-forming (for example, Na2O, MgO, Al2O3, SiO2, P2O5, SO3, Cl2O7) and non-salt-forming (for example, CO, N2O, NO, H2O). Salt-forming oxides are divided into... ... Technical Translator's Guide
OXIDES- chem. compounds of elements with oxygen (outdated name oxides); one of the most important classes of chemistry. substances. Oxygens are most often formed by the direct oxidation of simple and complex substances. Eg. Oxidation is formed during the oxidation of hydrocarbons.... ... Big Polytechnic Encyclopedia
Key Facts
Key Facts- Oil is flammable liquid, which is a complex mixture of hydrocarbons. Various types oils differ significantly in chemical and physical properties: in nature it is presented both in the form of black bitumen asphalt and in the form... ... Oil and Gas Microencyclopedia
Key Facts- Oil is a flammable liquid, which is a complex mixture of hydrocarbons. Different types of oil differ significantly in chemical and physical properties: in nature it is presented both in the form of black bitumen asphalt and in the form... ... Oil and Gas Microencyclopedia
Oxides- a combination of a chemical element with oxygen. According to their chemical properties, all oxides are divided into salt-forming (for example, Na2O, MgO, Al2O3, SiO2, P2O5, SO3, Cl2O7) and non-salt-forming (for example, CO, N2O, NO, H2O). Salt-forming oxides... ... Encyclopedic Dictionary of Metallurgy
Books
- , Gusev Alexander Ivanovich. Nonstoichiometry, caused by the presence of structural vacancies, is widespread in solid-phase compounds and creates the prerequisites for disordered or ordered distribution...
- Nonstoichiometry, disorder, short-range and long-range order in a solid, Gusev A.I.. Nonstoichiometry, caused by the presence of structural vacancies, is widespread in solid-phase compounds and creates the prerequisites for disordered or ordered distribution...
If you were not interested in chemistry at school, you are unlikely to immediately remember what oxides are and what their role is in environment. It is actually a fairly common type of compound and is most commonly found in the environment in the form of water, rust, carbon dioxide and sand. Oxides also include minerals - a type of rock that has a crystalline structure.
Definition
Oxides are chemical compounds whose formula contains at least one oxygen atom and atoms of other chemical elements. Metal oxides typically contain oxygen anions in the -2 oxidation state. A significant part of the Earth's crust consists of solid oxides that arose during the oxidation of elements with oxygen from air or water. When a hydrocarbon is burned, two main oxides of carbon are formed: carbon monoxide ( carbon monoxide, CO) and carbon dioxide (carbon dioxide, CO 2).
Oxides classification
All oxides are usually divided into two large groups:
- salt-forming oxides;
- non-salt-forming oxides.
Salt-forming oxides - chemical substances, which, in addition to oxygen, contain elements of metals and non-metals, which form acids upon contact with water, and when combined with bases - salts.
Salt-forming oxides are in turn divided into:
- basic oxides in which, upon oxidation, the second element (1, 2 and sometimes 3-valent metal) becomes a cation (Li 2 O, Na 2 O, K 2 O, CuO, Ag 2 O, MgO, CaO, SrO, BaO, HgO , MnО, CrO, NiО, Fr 2 O, Cs 2 O, Rb 2 O, FeO);
- acid oxides in which, when forming a salt, a second element is attached to a negatively charged oxygen atom (CO 2, SO 2, SO 3, SiO 2, P 2 O 5, CrO 3, Mn 2 O 7, NO 2, Cl 2 O 5, Cl 2 O 3);
- amphoteric oxides in which a second element (3 and 4 valent metals or such exceptions as zinc oxide, beryllium oxide, tin oxide and lead oxide) can become either a cation or join an anion (ZnO, Cr 2 O 3, Al 2 O 3, SnO, SnO 2, PbO, PbO 2, TiO 2, MnO 2, Fe 2 O 3, BeO).
Non-salt-forming oxides exhibit neither acidic, basic, nor amphoteric properties and, as the name implies, do not form salts (CO, NO, NO 2, (FeFe 2)O 4).
Properties of oxides
- Oxygen atoms in oxides have high chemical activity. Due to the fact that the oxygen atom is always negatively charged, it forms stable chemical bonds with almost all elements, which leads to a wide variety of oxides.
- Noble metals such as gold and platinum are valued because they do not oxidize naturally. Corrosion of metals occurs as a result of hydrolysis or oxidation with oxygen. The combination of water and oxygen only speeds up the reaction rate.
- In the presence of water and oxygen (or just air), the oxidation reaction of some elements, for example, sodium, occurs rapidly and can be dangerous to humans.
- Oxides create a protective oxide film on the surface. An example is aluminum foil, which, due to its coating of a thin film of aluminum oxide, corrodes much more slowly.
- The oxides of most metals have a polymer structure, so they are not destroyed by solvents.
- Oxides dissolve under the action of acids and bases. Oxides that can react with both acids and bases are called amphoteric. Metals typically form basic oxides, nonmetals form acidic oxides, and amphoteric oxides are derived from alkali metals (metalloids).
- The amount of metal oxide can be reduced by the action of certain organic compounds. These redox reactions underlie many important chemical transformations, such as the detoxification of drugs by P450 enzymes and the production of ethylene oxide, which is then used to make antifreeze.
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Oxides are called complex substances whose molecules include oxygen atoms in oxidation state - 2 and some other element.
can be obtained through the direct interaction of oxygen with another element, or indirectly (for example, during the decomposition of salts, bases, acids). Under normal conditions, oxides come in solid, liquid and gaseous states; this type of compound is very common in nature. Oxides are contained in Earth's crust. Rust, sand, water, carbon dioxide are oxides.
They are either salt-forming or non-salt-forming.
Salt-forming oxides- These are oxides that form salts as a result of chemical reactions. These are oxides of metals and non-metals, which, when interacting with water, form the corresponding acids, and when interacting with bases, the corresponding acidic and normal salts. For example, copper oxide (CuO) is a salt-forming oxide because, for example, when it interacts with hydrochloric acid(HCl) salt is formed:
CuO + 2HCl → CuCl 2 + H 2 O.
As a result of chemical reactions, other salts can be obtained:
CuO + SO 3 → CuSO 4.
Non-salt-forming oxides These are oxides that do not form salts. Examples include CO, N 2 O, NO.
Salt-forming oxides, in turn, are of 3 types: basic (from the word «
base »
), acidic and amphoteric.
Basic oxides These metal oxides are called those that correspond to hydroxides belonging to the class of bases. Basic oxides include, for example, Na 2 O, K 2 O, MgO, CaO, etc.
Chemical properties of basic oxides
1. Water-soluble basic oxides react with water to form bases:
Na 2 O + H 2 O → 2NaOH.
2. React with acid oxides, forming the corresponding salts
Na 2 O + SO 3 → Na 2 SO 4.
3. React with acids to form salt and water:
CuO + H 2 SO 4 → CuSO 4 + H 2 O.
4. React with amphoteric oxides:
Li 2 O + Al 2 O 3 → 2LiAlO 2.
If the composition of the oxides contains a non-metal or a metal exhibiting the highest valence (usually from IV to VII) as the second element, then such oxides will be acidic. Acidic oxides (acid anhydrides) are those oxides that correspond to hydroxides belonging to the class of acids. These are, for example, CO 2, SO 3, P 2 O 5, N 2 O 3, Cl 2 O 5, Mn 2 O 7, etc. Acidic oxides dissolve in water and alkalis, forming salt and water.
Chemical properties of acid oxides
1. React with water to form an acid:
SO 3 + H 2 O → H 2 SO 4.
But not all acidic oxides react directly with water (SiO 2, etc.).
2. React with based oxides to form a salt:
CO 2 + CaO → CaCO 3
3. React with alkalis, forming salt and water:
CO 2 + Ba(OH) 2 → BaCO 3 + H 2 O.
Part amphoteric oxide includes an element that has amphoteric properties. Amphotericity refers to the ability of compounds to exhibit acidic and basic properties depending on conditions. For example, zinc oxide ZnO can be either a base or an acid (Zn(OH) 2 and H 2 ZnO 2). Amphotericity is expressed in the fact that, depending on the conditions, amphoteric oxides exhibit either basic or acidic properties.
Chemical properties of amphoteric oxides
1. React with acids to form salt and water:
ZnO + 2HCl → ZnCl 2 + H 2 O.
2. React with solid alkalis (during fusion), forming as a result of the reaction salt - sodium zincate and water:
ZnO + 2NaOH → Na 2 ZnO 2 + H 2 O.
When zinc oxide interacts with an alkali solution (the same NaOH), another reaction occurs:
ZnO + 2 NaOH + H 2 O => Na 2.
Coordination number is a characteristic that determines the number of nearby particles: atoms or ions in a molecule or crystal. Each amphoteric metal has its own coordination number. For Be and Zn it is 4; For and Al it is 4 or 6; For and Cr it is 6 or (very rarely) 4;
Amphoteric oxides are usually insoluble in water and do not react with it.
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All chemical compounds existing in nature are divided into organic and inorganic. Among the latter, the following classes are distinguished: oxides, hydroxides, salts. Hydroxides are divided into bases, acids and amphoteric. Among the oxides one can also distinguish acidic, basic and amphoteric. Substances of the last group can exhibit both acidic and basic properties.
Chemical properties of acid oxides
Such substances have peculiar Chemical properties. Acidic oxides are capable of entering into chemical reactions only with basic hydroxides and oxides. This group of chemical compounds includes substances such as carbon dioxide, sulfur dioxide and trioxide, chromium trioxide, manganese heptoxide, phosphorus pentoxide, chlorine trioxide and pentoxide, nitrogen tetra- and pentoxide, and silicon dioxide.
Such substances are also called anhydrides. The acidic properties of oxides appear primarily during their reactions with water. In this case, a certain oxygen-containing acid is formed. For example, if you take sulfur trioxide and water in equal quantities, you get sulfate (sulfuric) acid. Phosphoric acid can be synthesized in the same way by adding water to phosphorus oxide. Reaction equation: P2O5 + 3H2O = 2H3PO4. In exactly the same way, it is possible to obtain acids such as nitrate, silicic, etc. Also, acidic oxides enter into chemical interaction with basic or amphoteric hydroxides. During this type of reaction, salt and water are formed. For example, if you take sulfur trioxide and add calcium hydroxide to it, you get calcium sulfate and water. If we add zinc hydroxide, we get zinc sulfate and water. Another group of substances with which these chemical compounds interact are basic and amphoteric oxides. When reacting with them, only salt is formed, without water. For example, adding amphoteric aluminum oxide to sulfur trioxide produces aluminum sulfate. And if you mix silicon oxide with basic calcium oxide, you get calcium silicate. In addition, acidic oxides react with basic and normal salts. When reacting with the latter, acidic salts are formed. For example, if you add calcium carbonate and water to carbon dioxide, you can get calcium bicarbonate. Reaction equation: CO 2 + CaCO 3 + H 2 O = Ca (HCO 3) 2. When acidic oxides react with basic salts, normal salts are formed.
Substances of this group do not interact with acids or other acidic oxides. Amphoteric oxides can exhibit exactly the same chemical properties, only in addition they also interact with acidic oxides and hydroxides, that is, they combine both acidic and basic properties.
Physical properties and applications of acid oxides
There are quite a few acid oxides with different physical properties, so it is possible to use them in the most different areas industry.
Sulfur trioxide
Most often this compound is used in the chemical industry. It is an intermediate product formed during the production of sulfate acid. This process involves burning iron pyrite to produce sulfur dioxide, which is then subjected to chemical reaction with oxygen, resulting in the formation of trioxide. Next, sulfuric acid is synthesized from the trioxide by adding water to it. At normal conditions this substance is a colorless liquid with unpleasant smell. At temperatures below sixteen degrees Celsius, sulfur trioxide solidifies, forming crystals.
Phosphorus pentoxide
Acidic oxides also include phosphorus pentoxide. It is a white snow-like substance. It is used as a water-removing agent due to the fact that it very actively interacts with water, forming phosphoric acid (it is also used in the chemical industry to extract it).
Carbon dioxide
It is the most common of the acid oxides in nature. The content of this gas in the Earth's atmosphere is about one percent. Under normal conditions, this substance is a gas that has neither color nor odor. Carbon dioxide is widely used in Food Industry: for the production of carbonated drinks, as a leavening agent, as a preservative (under the designation E290). Liquefied carbon dioxide is used to make fire extinguishers. This substance also plays a huge role in nature - for photosynthesis, which results in the formation of oxygen vital for animals. Plants need carbon dioxide. This substance is released during the combustion of all organic chemical compounds without exception.
Silica
Under normal conditions it appears as colorless crystals. In nature, it can be found in the form of many different minerals, such as quartz, crystal, chalcedony, jasper, topaz, amethyst, and morion. This acidic oxide is actively used in the production of ceramics, glass, abrasives, concrete products, fiber optic cables. This substance is also used in radio engineering. In the food industry it is used in the form of an additive coded under the name E551. Here it is used to maintain the original shape and consistency of the product. This food supplement can be found, for example, in instant coffee. In addition, silicon dioxide is used in the production of toothpastes.
Manganese heptaoxide
This substance is a brown-green mass. It is used mainly for the synthesis of manganese acid by adding water to the oxide.
Nitrogen pentoxide
It is a solid, colorless substance in the form of crystals. It is used in most cases in the chemical industry to produce nitric acid or other nitrogen oxides.
Chlorine trioxide and tetroxide
The first is a green-yellow gas, the second is a liquid of the same color. They are used mainly in the chemical industry to produce the corresponding chlorous acids.
Preparation of acid oxides
Substances of this group can be obtained due to the decomposition of acids under the influence of high temperatures. In this case, the desired substance and water are formed. Examples of reactions: H 2 CO 3 = H 2 O + CO 2; 2H 3 PO 4 = 3H 2 O + P 2 O 5. Manganese heptaoxide can be obtained by treating potassium permanganate with a concentrated solution of sulfate acid. As a result of this reaction, the desired substance, potassium sulfate and water, is formed. Carbon dioxide can be obtained due to the decomposition of carboxylic acid, the interaction of carbonates and bicarbonates with acids, and the reactions of baking soda with citric acid.
Conclusion
To summarize everything written above, we can say that acid oxides are widely used in the chemical industry. Only a few of them are also used in food and other industries.
Acidic oxides are large group inorganic chemical compounds that have great importance and can be used to produce a wide variety of oxygen-containing acids. This group also includes two important substances: carbon dioxide and silicon dioxide, the first of which plays a huge role in nature, and the second is presented in the form of many minerals, often used in the manufacture of jewelry.
Acidic oxides are a fairly large group of complex substances that react with alkalis. In this case, salts form. But they do not interact with acids.
Acidic oxides are formed predominantly by nonmetals. For example, this group includes sulfur, phosphorus and chlorine. In addition, substances with the same properties can be formed from so-called transition elements with a valence of five to seven.
Acidic oxides can form acids when interacting with water. Each has a corresponding oxide. For example, sulfur oxides form sulfate and sulfite acids, and phosphorus oxides form ortho- and metaphosphate acids.
Acidic oxides and methods for their preparation
There are several basic methods with
The most common method is the oxidation of non-metal atoms with oxygen. For example, when phosphorus reacts with oxygen, phosphorus oxide is obtained. Of course, this method is not always possible.
Another fairly common reaction is the so-called roasting of oxygen sulfides. In addition, oxides are also obtained by reacting certain salts with acids.
Sometimes laboratories use a slightly different technique. During the reaction, water is removed from the corresponding acid - the process of dehydration occurs. By the way, this is why acid oxides are also known under another name - acid anhydrides.
Chemical properties of acid oxides
As already mentioned, anhydrides can react with basic oxides or alkalis. As a result of this reaction, a salt of the corresponding acid is formed, and when reacting with a base, water is also formed. It is this process that characterizes the basic acidic properties of oxides. In addition, anhydrides do not react with acids.
Another property of these substances is the ability to react with amphoteric bases and oxides. As a result of this process, salts are also formed.
In addition, some anhydrides react with water. As a result of this process, the formation of the corresponding acid is observed. This is how, for example, sulfuric acid is produced in the laboratory.
The most common anhydrides: a brief description of
The most common and well-known acid oxide is carbon dioxide. This substance under normal conditions is a colorless, odorless gas, but with a faint sour taste.
By the way, when atmospheric pressure Carbon dioxide can exist either as a gas or as a solid. In order to turn carbon anhydride into a liquid, pressure must be increased. It is this property that is used to store the substance.
Carbon dioxide belongs to the group of greenhouse gases, because it actively absorbs emissions emitted by the earth, retaining heat in the atmosphere. However, this substance is very important for the life of organisms. Carbon dioxide is found in the atmosphere of our planet. In addition, it is used by plants in photosynthesis processes.
Sulfuric anhydride, or sulfur trioxide, is another representative of this group of substances. Under normal conditions, it is a colorless, very volatile liquid with an unpleasant, suffocating odor. This oxide is very important in the chemical industry, since the bulk of sulfuric acid is produced from it.
Silicon oxide is another fairly well-known substance, which in its normal state is crystalline. By the way, sand consists of exactly this compound. When heated, it can melt and harden. This property is used in glass production. In addition, the substance practically does not conduct electricity, so I use it as a dielectric.