Non-salt-forming (indifferent, indifferent) oxides CO, SiO, N 2 0, NO.

Salt-forming oxides:

Basic. Oxides whose hydrates are bases. Metal oxides with oxidation states +1 and +2 (less often +3). Examples: Na 2 O - sodium oxide, CaO - calcium oxide, CuO - copper (II) oxide, CoO - cobalt (II) oxide, Bi 2 O 3 - bismuth (III) oxide, Mn 2 O 3 - manganese (III) oxide ).

Amphoteric. Oxides whose hydrates are amphoteric hydroxides. Metal oxides with oxidation states +3 and +4 (less often +2). Examples: Al 2 O 3 - aluminum oxide, Cr 2 O 3 - chromium (III) oxide, SnO 2 - tin (IV) oxide, MnO 2 - manganese (IV) oxide, ZnO - zinc oxide, BeO - beryllium oxide.

Acidic. Oxides whose hydrates are oxygen-containing acids. Non-metal oxides. Examples: P 2 O 3 - phosphorus oxide (III), CO 2 - carbon oxide (IV), N 2 O 5 - nitrogen oxide (V), SO 3 - sulfur oxide (VI), Cl 2 O 7 - chlorine oxide ( VII). Metal oxides with oxidation states +5, +6 and +7. Examples: Sb 2 O 5 - antimony (V) oxide. CrOz - chromium (VI) oxide, MnOz - manganese (VI) oxide, Mn 2 O 7 - manganese (VII) oxide.

Change in the nature of oxides with increasing oxidation state of the metal

Physical properties

Oxides are solid, liquid and gaseous, of different colors. For example: copper (II) oxide CuO is black, calcium oxide CaO is white - solids. Sulfur oxide (VI) SO 3 is a colorless volatile liquid, and carbon monoxide (IV) CO 2 is a colorless gas under ordinary conditions.

State of aggregation

CaO, CuO, Li 2 O and other basic oxides; ZnO, Al 2 O 3, Cr 2 O 3 and other amphoteric oxides; SiO 2, P 2 O 5, CrO 3 and other acid oxides.

SO 3, Cl 2 O 7, Mn 2 O 7, etc.

Gaseous:

CO 2, SO 2, N 2 O, NO, NO 2, etc.

Solubility in water

Soluble:

a) basic oxides of alkali and alkaline earth metals;

b) almost all acid oxides (exception: SiO 2).

Insoluble:

a) all other basic oxides;

b) all amphoteric oxides

Chemical properties

1. Acid-base properties

Common properties of basic, acidic and amphoteric oxides are acid-base interactions, which are illustrated by the following diagram:

(only for oxides of alkali and alkaline earth metals) (except SiO 2).

Amphoteric oxides, having the properties of both basic and acidic oxides, interact with strong acids and alkalis:

2. Redox properties

If an element has a variable oxidation state (s.o.), then its oxides with low s. O. can exhibit reducing properties, and oxides with high c. O. - oxidative.

Examples of reactions in which oxides act as reducing agents:

Oxidation of oxides with low c. O. to oxides with high c. O. elements.

2C +2 O + O 2 = 2C +4 O 2

2S +4 O 2 + O 2 = 2S +6 O 3

2N +2 O + O 2 = 2N +4 O 2

Carbon (II) monoxide reduces metals from their oxides and hydrogen from water.

C +2 O + FeO = Fe + 2C +4 O 2

C +2 O + H 2 O = H 2 + 2C +4 O 2

Examples of reactions in which oxides act as oxidizing agents:

Reduction of oxides with high o. elements to oxides with low c. O. or to simple substances.

C +4 O 2 + C = 2C +2 O

2S +6 O 3 + H 2 S = 4S +4 O 2 + H 2 O

C +4 O 2 + Mg = C 0 + 2MgO

Cr +3 2 O 3 + 2Al = 2Cr 0 + 2Al 2 O 3

Cu +2 O + H 2 = Cu 0 + H 2 O

The use of oxides of low-active metals for the oxidation of organic substances.

Some oxides in which the element has an intermediate c. o., capable of disproportionation;

For example:

2NO 2 + 2NaOH = NaNO 2 + NaNO 3 + H 2 O

Methods of obtaining

1. Interaction of simple substances - metals and non-metals - with oxygen:

4Li + O 2 = 2Li 2 O;

2Cu + O 2 = 2CuO;

4P + 5O 2 = 2P 2 O 5

2. Dehydration of insoluble bases, amphoteric hydroxides and some acids:

Cu(OH) 2 = CuO + H 2 O

2Al(OH) 3 = Al 2 O 3 + 3H 2 O

H 2 SO 3 = SO 2 + H 2 O

H 2 SiO 3 = SiO 2 + H 2 O

3. Decomposition of some salts:

2Cu(NO 3) 2 = 2CuO + 4NO 2 + O 2

CaCO 3 = CaO + CO 2

(CuOH) 2 CO 3 = 2CuO + CO 2 + H 2 O

4. Oxidation of complex substances with oxygen:

CH 4 + 2O 2 = CO 2 + H 2 O

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

4NH 3 + 5O 2 = 4NO + 6H 2 O

5. Reduction of oxidizing acids with metals and non-metals:

Cu + H 2 SO 4 (conc) = CuSO 4 + SO 2 + 2H 2 O

10HNO 3 (conc) + 4Ca = 4Ca(NO 3) 2 + N 2 O + 5H 2 O

2HNO 3 (diluted) + S = H 2 SO 4 + 2NO

6. Interconversions of oxides during redox reactions (see redox properties of oxides).

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 they can be used in a wide variety of industries.

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 a chemical reaction with oxygen to form trioxide. Next, sulfuric acid is synthesized from the trioxide by adding water to it. Under normal conditions, this substance is a colorless liquid with an unpleasant odor. 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 the food industry: for the production of carbonated drinks, as a leavening agent, and 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, and 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 additive 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 a large group of inorganic chemical compounds that are of 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.

Oxides are complex substances consisting of two elements, one of which is oxygen. Oxides can be salt-forming and non-salt-forming: one type of salt-forming oxides is basic oxides. How do they differ from other species, and what are their chemical properties?

Salt-forming oxides are divided into basic, acidic and amphoteric oxides. If basic oxides correspond to bases, then acidic oxides correspond to acids, and amphoteric oxides correspond to amphoteric formations. Amphoteric oxides are those compounds that, depending on conditions, can exhibit either basic or acidic properties.

Rice. 1. Classification of oxides.

The physical properties of oxides are very diverse. They can be either gases (CO 2), solids (Fe 2 O 3) or liquid substances (H 2 O).

However, most basic oxides are solids of various colors.

oxides in which elements exhibit their highest activity are called higher oxides. The order of increase in the acidic properties of higher oxides of the corresponding elements in periods from left to right is explained by a gradual increase in the positive charge of the ions of these elements.

Chemical properties of basic oxides

Basic oxides are the oxides to which bases correspond. For example, the basic oxides K 2 O, CaO correspond to the bases KOH, Ca(OH) 2.

Rice. 2. Basic oxides and their corresponding bases.

Basic oxides are formed by typical metals, as well as metals of variable valency in the lowest oxidation state (for example, CaO, FeO), react with acids and acid oxides, forming salts:

CaO (basic oxide) + CO 2 (acid oxide) = CaCO 3 (salt)

FeO (basic oxide)+H 2 SO 4 (acid)=FeSO 4 (salt)+2H 2 O (water)

Basic oxides also react with amphoteric oxides, resulting in the formation of a salt, for example:

Only oxides of alkali and alkaline earth metals react with water:

BaO (basic oxide)+H 2 O (water)=Ba(OH) 2 (alkali earth metal base)

Many basic oxides tend to be reduced to substances consisting of atoms of one chemical element:

3CuO+2NH 3 =3Cu+3H 2 O+N 2

When heated, only oxides of mercury and noble metals decompose:

Rice. 3. Mercury oxide.

List of main oxides:

Oxide name	Chemical formula	Properties
Calcium oxide	CaO	quicklime, white crystalline substance
Magnesium oxide	MgO	white substance, slightly soluble in water
Barium oxide	BaO	colorless crystals with a cubic lattice
Copper oxide II	CuO	black substance practically insoluble in water
	HgO	red or yellow-orange solid
Potassium oxide	K2O	colorless or pale yellow substance
Sodium oxide	Na2O	substance consisting of colorless crystals
Lithium oxide	Li2O	a substance consisting of colorless crystals that have a cubic lattice structure

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 found in the 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 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 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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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 (classified) into 4 groups:

Na 2 O– Sodium oxide

CaO – Calcium Oxide

Fe 2 O 3 – iron (III) oxide

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

CO 2 – Carbon monoxide (IV)

P 2 O 5 – Phosphorus (V) oxide

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 (III) oxide

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 producing oxides.

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

4Na + O 2 = 2Na 2 O

4P + 5O 2 = 2P 2 O 5

2). Combustion, i.e. interaction with oxygen of a complex substance (consisting of two elements) thus forming 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 = H 2 O + CO 2

H 2 SO 3 = H 2 O + SO 2

H 2 SiO 3 = H 2 O + SiO 2

4). Decomposition insoluble grounds. A basic oxide and water are formed.

Mg(OH) 2 = MgO + H 2 O

2Al(OH) 3 = Al 2 O 3 + 3H 2 O

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

CaCO 3 = CaO + CO 2

MgSO 3 = MgO + SO 2

Chemical properties.

I. Basic oxides.

alkali.

Na 2 O + H 2 O = 2NaOH

CaO + H 2 O = Ca(OH) 2

СuO + H 2 O = the reaction does not occur, because possible base containing copper - insoluble

2). Interaction with acids, resulting in the formation of salt and water. (Base oxide and acids ALWAYS react)

K2O + 2HCI = 2KCl + H2O

CaO + 2HNO 3 = Ca(NO 3) 2 + H 2 O

3). Interaction with acidic oxides, resulting in the formation of salt.

Li 2 O + CO 2 = Li 2 CO 3

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

4). Interaction with hydrogen produces metal and water.

CuO + H 2 = Cu + H 2 O

Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O

II.Acidic oxides.

1). Interaction with water should form acid.(OnlySiO 2 does not interact with water)

CO 2 + H 2 O = H 2 CO 3

P 2 O 5 + 3H 2 O = 2H 3 PO 4

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

SO 3 + 2KOH = K 2 SO 4 + H 2 O

N 2 O 5 + 2KOH = 2KNO 3 + H 2 O

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

N 2 O 5 + K 2 O = 2KNO 3

Al 2 O 3 + 3SO 3 = Al 2 (SO 4) 3

Basic exercises.

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

K 2 O + P 2 O 5 =

Solution.

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

3K 2 O + P 2 O 5 = 2K 3 RO 4

type of reaction - compound (since two substances react, but 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). Let's number each arrow. Therefore, it is necessary to write down 4 equations. The substance written to the left of the arrow (starting substance) reacts, and the substance written to the right is formed as a result of the reaction (reaction product). Let's decipher the first part of the recording:

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

2Ca + O 2 → 2CaO

Let's move on to transformation No. 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 No. 3

Ca(OH) 2 → CaCO 3

Ca(OH) 2 + ….. = CaCO 3 + …….

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

Ca(OH) 2 + CO 2 = CaCO 3 + H 2 O

Let's move on to transformation No. 4

CaCO 3 → CaO

CaCO 3 = ….. 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 = CaO + CO 2

3). Which of the following substances does CO 2 interact with? Write the reaction equations.

A). Hydrochloric acid B). Sodium hydroxide B). Potassium oxide d). Water

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

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

1). CO 2 + 2NaOH = Na 2 CO 3 + H 2 O

2). CO 2 + K 2 O = K 2 CO 3