1. Metal + Non-metal. Inert gases do not enter into this interaction. The higher the electronegativity of a non-metal, the more metals it will react with. For example, fluorine reacts with all metals, and hydrogen only with active ones. The further to the left a metal is in the activity series of metals, the more non-metals it can react with. For example, gold reacts only with fluorine, lithium with all non-metals.

2. Non-metal + non-metal. In this case, a more electronegative non-metal acts as an oxidizing agent, less EO - as a reducing agent. Non-metals with similar electronegativity do not interact well with each other, for example, the interaction of phosphorus with hydrogen and silicon with hydrogen is practically impossible, since the equilibrium of these reactions is shifted towards the formation of simple substances. Helium, neon and argon do not react with non-metals, other inert gases under harsh conditions can react with fluorine.
Oxygen does not interact with chlorine, bromine and iodine. Oxygen can react with fluorine at low temperatures.

3. Metal + acid oxide. Metal restores non-metal from oxide. The excess metal can then react with the resulting non-metal. For example:

2 Mg + SiO 2 \u003d 2 MgO + Si (for lack of magnesium)

2 Mg + SiO 2 \u003d 2 MgO + Mg 2 Si (with excess magnesium)

4. Metal + acid. Metals to the left of hydrogen in the voltage series react with acids to release hydrogen.

The exception is acids - oxidizing agents (concentrated sulfuric and any nitric acid), which can react with metals that are in the series of voltages to the right of hydrogen, hydrogen is not released in the reactions, but water and the acid reduction product are obtained.

It is necessary to pay attention to the fact that when a metal interacts with an excess of a polybasic acid, an acid salt can be obtained: Mg +2 H 3 PO 4 \u003d Mg (H 2 PO 4) 2 + H 2.

If the product of the interaction of the acid and the metal is an insoluble salt, then the metal is passivated, since the surface of the metal is protected from the action of the acid by the insoluble salt. For example, the action of dilute sulfuric acid on lead, barium or calcium.

5. Metal + salt. in solution this reaction involves a metal to the right of magnesium in the voltage series, including magnesium itself, but to the left of the salt metal. If the metal is more active than magnesium, then it does not react with salt, but with water to form alkali, which then reacts with salt. In this case, the initial salt and the resulting salt must be soluble. The insoluble product passivates the metal.

However, there are exceptions to this rule:

2FeCl 3 + Cu \u003d CuCl 2 + 2FeCl 2;

2FeCl 3 + Fe = 3FeCl 2 . Since iron has an intermediate oxidation state, its salt in the highest oxidation state is easily reduced to a salt in an intermediate oxidation state, oxidizing even less active metals.

in meltsa number of metal stresses do not work. It is possible to determine whether a reaction between a salt and a metal is possible only with the help of thermodynamic calculations. For example, sodium can displace potassium from a potassium chloride melt, since potassium is more volatile: Na + KCl = NaCl + K (this reaction is determined by the entropy factor). On the other hand, aluminum was obtained by displacement from sodium chloride: 3 Na + AlCl 3 \u003d 3 NaCl + Al . This process is exothermic and is determined by the enthalpy factor.

It is possible that the salt decomposes when heated, and the products of its decomposition can react with the metal, such as aluminum nitrate and iron. Aluminum nitrate decomposes when heated to alumina, nitric oxide ( IV ) and oxygen, oxygen and nitric oxide will oxidize iron:

10Fe + 2Al(NO 3) 3 = 5Fe 2 O 3 + Al 2 O 3 + 3N 2

6. Metal + basic oxide. Also, as in molten salts, the possibility of these reactions is determined thermodynamically. Aluminum, magnesium and sodium are often used as reducing agents. For example: 8 Al + 3 Fe 3 O 4 \u003d 4 Al 2 O 3 + 9 Fe exothermic reaction, enthalpy factor);2 Al + 3 Rb 2 O = 6 Rb + Al 2 O 3 (volatile rubidium, enthalpy factor).

8. Non-metal + base. As a rule, the reaction takes place between a non-metal and an alkali. Not all non-metals can react with alkalis: it must be remembered that halogens enter into this interaction (differently depending on temperature), sulfur (when heated), silicon, phosphorus.

KOH + Cl 2 \u003d KClO + KCl + H 2 O (in the cold)

6 KOH + 3 Cl 2 = KClO 3 + 5 KCl + 3 H 2 O (in hot solution)

6KOH + 3S = K 2 SO 3 + 2K 2 S + 3H 2 O

2KOH + Si + H 2 O \u003d K 2 SiO 3 + 2H 2

3KOH + 4P + 3H 2 O = PH 3 + 3KPH 2 O 2

1) non-metal - reducing agent (hydrogen, carbon):

CO 2 + C \u003d 2CO;

2NO 2 + 4H 2 \u003d 4H 2 O + N 2;

SiO 2 + C \u003d CO 2 + Si. If the resulting non-metal can react with the metal used as a reducing agent, then the reaction will go further (with an excess of carbon) SiO 2 + 2 C \u003d CO 2 + Si C

2) non-metal - oxidizing agent (oxygen, ozone, halogens):

2C O + O 2 \u003d 2CO 2.

WITH O + Cl 2 \u003d CO Cl 2.

2 NO + O 2 \u003d 2 N O 2.

10. Acid oxide + basic oxide . The reaction proceeds if the resulting salt exists in principle. For example, aluminum oxide can react with sulfuric anhydride to form aluminum sulfate, but cannot react with carbon dioxide, since the corresponding salt does not exist.

11. Water + basic oxide . The reaction is possible if an alkali is formed, that is, a soluble base (or slightly soluble, in the case of calcium). If the base is insoluble or slightly soluble, then there is a reverse reaction of decomposition of the base into oxide and water.

12. Basic oxide + acid . The reaction is possible if the resulting salt exists. If the resulting salt is insoluble, then the reaction may be passivated by blocking the access of the acid to the surface of the oxide. In the case of an excess of a polybasic acid, the formation of an acid salt is possible.

13. acid oxide + base. As a rule, the reaction goes between alkali and acid oxide. If the acid oxide corresponds to a polybasic acid, an acid salt can be obtained: CO 2 + KOH = KHCO 3 .

Acid oxides corresponding to strong acids can also react with insoluble bases.

Sometimes oxides corresponding to weak acids react with insoluble bases, and an average or basic salt can be obtained (as a rule, a less soluble substance is obtained): 2 Mg (OH) 2 + CO 2 \u003d (MgOH) 2 CO 3 + H 2 O.

14. acid oxide + salt. The reaction can take place in the melt and in solution. In the melt, the less volatile oxide displaces the more volatile oxide from the salt. In solution, the oxide corresponding to the stronger acid displaces the oxide corresponding to the weaker acid. For example, Na 2 CO 3 + SiO 2 \u003d Na 2 SiO 3 + CO 2 , in the forward direction, this reaction proceeds in the melt, carbon dioxide is more volatile than silicon oxide; in the opposite direction, the reaction proceeds in solution, carbonic acid is stronger than silicic acid, and silicon oxide precipitates.

It is possible to combine an acid oxide with its own salt, for example, dichromate can be obtained from chromate, and disulfate can be obtained from sulfate, and disulfite can be obtained from sulfite:

Na 2 SO 3 + SO 2 \u003d Na 2 S 2 O 5

To do this, you need to take a crystalline salt and pure oxide, or a saturated salt solution and an excess of acidic oxide.

In solution, salts can react with their own acid oxides to form acid salts: Na 2 SO 3 + H 2 O + SO 2 \u003d 2 NaHSO 3

15. Water + acid oxide . The reaction is possible if a soluble or slightly soluble acid is formed. If the acid is insoluble or slightly soluble, then there is a reverse reaction of the decomposition of the acid into oxide and water. For example, sulfuric acid is characterized by the reaction of obtaining from oxide and water, the decomposition reaction practically does not occur, silicic acid cannot be obtained from water and oxide, but it easily decomposes into these components, but carbonic and sulfurous acid can participate in both direct and reverse reactions.

16. Base + acid. The reaction proceeds if at least one of the reactants is soluble. Depending on the ratio of reagents, medium, acidic and basic salts can be obtained.

17. Base + salt. The reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or weak electrolyte (precipitate, gas, water) is obtained as a product.

18. Salt + acid. As a rule, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a weak electrolyte (precipitate, gas, water) is obtained as a product.

A strong acid can react with insoluble salts of weak acids (carbonates, sulfides, sulfites, nitrites), and a gaseous product is released.

Reactions between concentrated acids and crystalline salts are possible if a more volatile acid is obtained: for example, hydrogen chloride can be obtained by the action of concentrated sulfuric acid on crystalline sodium chloride, hydrogen bromide and hydrogen iodine can be obtained by the action of orthophosphoric acid on the corresponding salts. It is possible to act with an acid on its own salt to obtain an acid salt, for example: BaSO 4 + H 2 SO 4 \u003d Ba (HSO 4) 2.

19. Salt + salt.As a rule, the reaction proceeds if both starting materials are soluble, and at least one non-electrolyte or a weak electrolyte is obtained as a product.

1) salt does not exist because irreversibly hydrolyzed . These are the majority of carbonates, sulfites, sulfides, silicates of trivalent metals, as well as some salts of divalent metals and ammonium. Trivalent metal salts are hydrolyzed to the corresponding base and acid, and divalent metal salts to less soluble basic salts.

Consider examples:

2 FeCl 3 + 3 Na 2 CO 3 = Fe 2 ( CO 3 ) 3 + 6 NaCl (1)

Fe 2 (CO 3) 3+ 6H 2 O \u003d 2Fe (OH) 3 + 3 H2CO3

H 2 CO 3 decomposes into water and carbon dioxide, the water in the left and right parts is reduced and it turns out: Fe 2 ( CO 3 ) 3 + 3 H 2 O \u003d 2 Fe (OH) 3 + 3 CO 2 (2)

If we now combine (1) and (2) equations and reduce iron carbonate, we get the total equation reflecting the interaction of ferric chloride ( III ) and sodium carbonate: 2 FeCl 3 + 3 Na 2 CO 3 + 3 H 2 O \u003d 2 Fe (OH) 3 + 3 CO 2 + 6 NaCl

CuSO 4 + Na 2 CO 3 \u003d CuCO 3 + Na 2 SO 4 (1)

The underlined salt does not exist due to irreversible hydrolysis:

2CuCO3+ H 2 O \u003d (CuOH) 2 CO 3 + CO 2 (2)

If we now combine (1) and (2) equations and reduce the copper carbonate, we get the total equation reflecting the interaction of sulfate ( II ) and sodium carbonate:

2CuSO 4 + 2Na 2 CO 3 + H 2 O \u003d (CuOH) 2 CO 3 + CO 2 + 2Na 2 SO 4

Oxides.

These are complex substances consisting of TWO elements, one of which is oxygen. For example:

CuO– copper(II) oxide

AI 2 O 3 - aluminum oxide

SO 3 - sulfur oxide (VI)

Oxides are divided (they are classified) into 4 groups:

Na 2 O– Sodium oxide

CaO - calcium oxide

Fe 2 O 3 - iron oxide (III)

2). Acidic- These are oxides non-metals. And sometimes metals if the oxidation state of the metal> 4. For example:

CO 2 - Carbon monoxide (IV)

P 2 O 5 - Phosphorus oxide (V)

SO 3 - Sulfur oxide (VI)

3). Amphoteric- These are oxides that have the properties of both basic and acidic oxides. You need to know the five most common amphoteric oxides:

BeO-beryllium oxide

ZnO– Zinc Oxide

AI 2 O 3 - Aluminum oxide

Cr 2 O 3 - Chromium (III) oxide

Fe 2 O 3 - Iron oxide (III)

4). Non-salt-forming (indifferent)- These are oxides that do not exhibit the properties of either basic or acidic oxides. There are three oxides to remember:

CO - carbon monoxide (II) carbon monoxide

NO– nitric oxide (II)

N 2 O– nitric oxide (I) laughing gas, nitrous oxide

Methods for obtaining oxides.

one). Combustion, i.e. interaction with oxygen of a simple substance:

4Na + O 2 \u003d 2Na 2 O

4P + 5O 2 \u003d 2P 2 O 5

2). Combustion, i.e. interaction with oxygen of a complex substance (consisting of two elements) in this case, two oxides.

2ZnS + 3O 2 = 2ZnO + 2SO 2

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2

3). Decomposition three weak acids. Others do not decompose. In this case, acid oxide and water are formed.

H 2 CO 3 \u003d H 2 O + CO 2

H 2 SO 3 \u003d H 2 O + SO 2

H 2 SiO 3 \u003d H 2 O + SiO 2

4). Decomposition insoluble grounds. Basic oxide and water are formed.

Mg(OH) 2 \u003d MgO + H 2 O

2Al(OH) 3 \u003d Al 2 O 3 + 3H 2 O

five). Decomposition insoluble salts. A basic oxide and an acidic oxide are formed.

CaCO 3 \u003d CaO + CO 2

MgSO 3 \u003d MgO + SO 2

Chemical properties.

I. basic oxides.

alkali.

Na 2 O + H 2 O \u003d 2NaOH

CaO + H 2 O \u003d Ca (OH) 2

СuO + H 2 O = the reaction does not proceed, because a possible base containing copper is insoluble

2). Reacts with acids to form salt and water. (Basic oxide and acids ALWAYS react)

K 2 O + 2HCI \u003d 2KCl + H 2 O

CaO + 2HNO 3 \u003d Ca (NO 3) 2 + H 2 O

3). Reaction with acidic oxides to form a salt.

Li 2 O + CO 2 \u003d Li 2 CO 3

3MgO + P 2 O 5 \u003d Mg 3 (PO 4) 2

4). Hydrogen reacts to form metal and water.

CuO + H 2 \u003d Cu + H 2 O

Fe 2 O 3 + 3H 2 \u003d 2Fe + 3H 2 O

II.Acid oxides.

one). Interaction with water, this should form acid.(OnlySiO 2 does not interact with water)

CO 2 + H 2 O \u003d H 2 CO 3

P 2 O 5 + 3H 2 O \u003d 2H 3 PO 4

2). Interaction with soluble bases (alkalis). This produces salt and water.

SO 3 + 2KOH \u003d K 2 SO 4 + H 2 O

N 2 O 5 + 2KOH \u003d 2KNO 3 + H 2 O

3). Interaction with basic oxides. In this case, only salt is formed.

N 2 O 5 + K 2 O \u003d 2KNO 3

Al 2 O 3 + 3SO 3 \u003d Al 2 (SO 4) 3

Basic exercises.

one). Complete the reaction equation. Determine its type.

K 2 O + P 2 O 5 \u003d

Solution.

In order to write down what is formed as a result, it is necessary to determine which substances reacted - here it is potassium oxide (basic) and phosphorus oxide (acid) according to the properties - the result should be SALT (see property No. 3) and the salt consists of atoms metals (in our case, potassium) and an acid residue which includes phosphorus (i.e. PO 4 -3 - phosphate) Therefore

3K 2 O + P 2 O 5 \u003d 2K 3 RO 4

type of reaction - compound (since two substances react, and one is formed)

2). Carry out transformations (chain).

Ca → CaO → Ca(OH) 2 → CaCO 3 → CaO

Solution

To complete this exercise, you must remember that each arrow is one equation (one chemical reaction). We number each arrow. Therefore, it is necessary to write down 4 equations. The substance written to the left of the arrow (the starting substance) enters into the reaction, and the substance written to the right is formed as a result of the reaction (the reaction product). Let's decipher the first part of the record:

Ca + ... .. → CaO We pay attention that a simple substance reacts, and an oxide is formed. Knowing the methods for obtaining oxides (No. 1), we come to the conclusion that in this reaction it is necessary to add -oxygen (O 2)

2Са + О 2 → 2СаО

Let's move on to transformation number 2

CaO → Ca(OH) 2

CaO + ... ... → Ca (OH) 2

We come to the conclusion that here it is necessary to apply the property of basic oxides - interaction with water, because only in this case a base is formed from the oxide.

CaO + H 2 O → Ca (OH) 2

Let's move on to transformation number 3

Ca (OH) 2 → CaCO 3

Сa(OH) 2 + ….. = CaCO 3 + …….

We come to the conclusion that here we are talking about carbon dioxide CO 2 since. only it, when interacting with alkalis, forms a salt (see property No. 2 of acid oxides)

Ca (OH) 2 + CO 2 \u003d CaCO 3 + H 2 O

Let's move on to transformation number 4

CaCO 3 → CaO

CaCO 3 \u003d ... .. CaO + ......

We come to the conclusion that more CO 2 is formed here, because. CaCO 3 is an insoluble salt, and it is during the decomposition of such substances that oxides are formed.

CaCO 3 \u003d CaO + CO 2

3). Which of the following substances interacts with CO 2 . Write reaction equations.

BUT). hydrochloric acid b. Sodium hydroxide B). Potassium oxide d. Water

D). Hydrogen E). Sulfur oxide (IV).

We determine that CO 2 is an acid oxide. And acidic oxides react with water, alkalis and basic oxides ... Therefore, from the list above, we select answers B, C, D And it is with them that we write down the reaction equations:

one). CO 2 + 2NaOH \u003d Na 2 CO 3 + H 2 O

2). CO 2 + K 2 O \u003d K 2 CO 3

Chemical properties of basic oxides

Details about oxides, their classification and methods of obtaining can be read .

1. Interaction with water. Only basic oxides are capable of reacting with water, which correspond to soluble hydroxides (alkalis). Alkalis form alkali metals (lithium, sodium, potassium, rubidium and cesium) and alkaline earth metals (calcium, strontium, barium). Oxides of other metals do not chemically react with water. Magnesium oxide reacts with water when boiled.

CaO + H 2 O → Ca (OH) 2

CuO + H 2 O ≠

2. Interaction with acid oxides and acids. When basic oxides react with acids, a salt of this acid and water are formed. When a basic oxide and an acid react, a salt is formed:

basic oxide + acid = salt + water

basic oxide + acid oxide = salt

When basic oxides interact with acids and their oxides, the rule works:

At least one of the reagents must correspond to a strong hydroxide (alkali or strong acid).

In other words, basic oxides, which correspond to alkalis, react with all acidic oxides and their acids. Basic oxides, which correspond to insoluble hydroxides, react only with strong acids and their oxides (N 2 O 5, NO 2, SO 3, etc.).

3. Interaction with amphoteric oxides and hydroxides.

When basic oxides interact with amphoteric ones, salts are formed:

basic oxide + amphoteric oxide = salt

During fusion, they interact with amphoteric oxides only basic oxides, which correspond to alkalis . This produces salt. The metal in the salt is taken from the more basic oxide, the acidic residue from the more acidic. IN this case amphoteric oxide forms an acid residue.

K 2 O + Al 2 O 3 → 2KAlO 2

CuO + Al 2 O 3 ≠ (there is no reaction, because Cu (OH) 2 is an insoluble hydroxide)

(to determine the acid residue, add a water molecule to the formula of an amphoteric or acid oxide: Al 2 O 3 + H 2 O \u003d H 2 Al 2 O 4 and divide the resulting indices in half if the oxidation state of the element is odd: HAlO 2. It turns out an aluminate ion AlO 2 - The charge of the ion is easy to determine by the number of attached hydrogen atoms - if the hydrogen atom is 1, then the charge of the anion will be -1, if 2 hydrogen, then -2, etc.).

Amphoteric hydroxides decompose when heated, so they cannot actually react with basic oxides.

4. Interaction of basic oxides with reducing agents.

Thus, the ions of some metals are oxidizing agents (the more to the right in the series of voltages, the stronger). When interacting with reducing agents, metals go into oxidation state 0.

4.1. Recovery with coal or carbon monoxide.

Carbon (coal) restores from oxides only metals located in the activity series after aluminum. The reaction proceeds only when heated.

FeO + C → Fe + CO

Carbon monoxide also restores from oxides only metals located after aluminum in the electrochemical series:

Fe 2 O 3 + CO → Al 2 O 3 + CO 2

CuO + CO → Cu + CO 2

4.2. Hydrogen reduction .

Hydrogen reduces oxides only to metals located in the activity series to the right of aluminum. The reaction with hydrogen proceeds only under harsh conditions - under pressure and when heated.

CuO + H 2 → Cu + H 2 O

4.3. Recovery with more active metals (in melt or solution, depending on the metal)

In this case, more active metals displace less active ones. That is, the metal added to the oxide should be located to the left in the activity series than the metal from the oxide. Reactions usually proceed when heated.

For example , zinc oxide interacts with aluminum:

3ZnO + 2Al → Al 2 O 3 + 3Zn

but does not interact with copper:

ZnO + Cu ≠

Recovery of metals from oxides with the help of other metals is a very common process. Often, aluminum and magnesium are used to restore metals. But alkali metals are not very suitable for this - they are too chemically active, which creates difficulties when working with them.

For example, cesium explodes in air.

Aluminothermy is the reduction of metals from aluminum oxides.

For example : aluminum restores copper (II) oxide from oxide:

3CuO + 2Al → Al 2 O 3 + 3Cu

magnesiumthermy is the reduction of metals from magnesium oxides.

CuO + H 2 → Cu + H 2 O

4.4. Recovery with ammonia.

Ammonia can only reduce oxides of inactive metals. The reaction proceeds only at high temperature.

For example , ammonia reduces copper (II) oxide:

3CuO + 2NH 3 → 3Cu + 3H 2 O + N 2

5. Interaction of basic oxides with oxidizing agents.

Under the action of oxidizing agents, some basic oxides (in which metals can increase the degree of oxidation, for example, Fe 2+ , Cr 2+ , Mn 2+ , etc.) can act as reducing agents.

For example ,iron(II) oxide can be oxidized with oxygen to iron(III) oxide:

4FeO + O 2 → 2Fe 2 O 3

If you were not fond of 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 that occurs most frequently in the environment in the form of water, rust, carbon dioxide, and sand. Oxides also include minerals - the species rocks having a crystalline structure.

Definition

Oxides are chemical compounds whose formula contains at least one oxygen atom and atoms of other chemical elements. Metal oxides generally contain oxygen anions in the -2 oxidation state. A significant part of the Earth's crust consists of solid oxides, which arose during the oxidation of elements with oxygen from air or water. In the process of burning hydrocarbons, two main oxides of carbon are formed: carbon monoxide (carbon monoxide, CO) and carbon dioxide (carbon dioxide, CO 2).

Classification of oxides

All oxides are usually divided into two large groups:

• salt-forming oxides;
• non-salt-forming oxides.

Salt-forming oxides - chemical substances, in which, in addition to oxygen, elements of metals and non-metals are contained, which form acids upon contact with water, and when combined with bases - salts.

Salt-forming oxides, in turn, are 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 , MnO, CrO, NiO, Fr 2 O, Cs 2 O, Rb 2 O, FeO);
• acid oxides, in which, during the formation of a salt, the 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 O3);
• amphoteric oxides, in which the second element (3 and 4-valent metals or such exceptions as zinc oxide, beryllium oxide, tin oxide and lead oxide) can become both a cation and 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 nor basic nor amphoteric properties and, as the name implies, do not form salts (CO, NO, NO 2, (FeFe 2)O 4).

Properties of oxides

1. Oxygen atoms in oxides are highly reactive. 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.
2. noble metals, such as gold and platinum, are valued due to the fact that they do not oxidize naturally. Corrosion of metals is formed as a result of hydrolysis or oxidation by oxygen. The combination of water and oxygen only speeds up the rate of the reaction.
3. In the presence of water and oxygen (or simply air), the oxidation reaction of some elements, such as sodium, occurs rapidly and can be dangerous to humans.
4. Oxides create a protective oxide film on the surface. An example is aluminum foil, which, due to the coating of a thin film of aluminum oxide, corrodes much more slowly.
5. The oxides of most metals have a polymeric structure, due to which they are not destroyed by the action of solvents.
6. Oxides dissolve under the action of acids and bases. Oxides that can react with both acids and bases are called amphoteric. Metals, as a rule, form basic oxides, non-metals - acidic oxides, and amphoteric oxides are obtained from alkali metals (metalloids).
7. The amount of metal oxide can be reduced by the action of some organic compounds. Such 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 complex substances are called, the composition of the molecules of which includes oxygen atoms in the oxidation state - 2 and some other element.

can be obtained by direct interaction of oxygen with another element, or indirectly (for example, by the decomposition of salts, bases, acids). IN normal conditions oxides are in solid, liquid and gaseous state, this type of compounds is very common in nature. oxides are found in Earth's crust. Rust, sand, water, carbon dioxide are oxides.

They are salt-forming and non-salt-forming.

Salt-forming oxides are oxides that, as a result, chemical reactions form salts. 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 reacts with hydrochloric acid (HCl), a 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 called oxides that do not form salts. An example is CO, N 2 O, NO.

Salt-forming oxides, in turn, are of 3 types: basic (from the word « base » ), acidic and amphoteric.

Basic oxides such metal oxides are called, which 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. Interact 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 second element in the composition of the oxides is a non-metal or a metal exhibiting a higher valency (usually exhibits from IV to VII), then such oxides will be acidic. Acid oxides (acid anhydrides) are oxides that correspond to hydroxides belonging to the class of acids. This is, for example, CO 2, SO 3, P 2 O 5, N 2 O 3, Cl 2 O 5, Mn 2 O 7, etc. Acid oxides dissolve in water and alkalis, forming salt and water.

Chemical properties of acid oxides

1. Interact with water, forming acid:

SO 3 + H 2 O → H 2 SO 4.

But not all acidic oxides directly react with water (SiO 2 and others).

2. React with based oxides to form a salt:

CO 2 + CaO → CaCO 3

3. Interact 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 is understood as the ability of compounds to exhibit acidic and basic properties depending on the conditions. For example, zinc oxide ZnO can be both a base and 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. Interact 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 - a characteristic that determines the number of nearest 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 is 4 or 6; For and Cr it is 6 or (very rarely) 4;

Amphoteric oxides usually do not dissolve in water and do not react with it.

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