Oxides are a very common type of compound found in earth's crust and in the universe in general.

Classification of oxides

Salt-forming oxides - these are oxides, which as a result chemical reaction 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.

• • basic oxides(for example, sodium oxide Na2O, copper (II) oxide CuO): metal oxides, the oxidation state of which is I-II;
  • acid oxides(for example, sulfur oxide (VI) SO3, nitric oxide (IV) NO2): metal oxides with an oxidation state of V-VII and non-metal oxides;
  • amphoteric oxides (for example, zinc oxide ZnO, aluminum oxide Al2O3): metal oxides with oxidation states III-IV and exceptions (ZnO, BeO, SnO, PbO).

Non-salt-forming oxides:

carbon monoxide(II) CO, nitric oxide(I) N2O, nitric oxide(II) NO, silicon oxide(II) SiO.

Basic properties of chemical oxides

1.Water-soluble basic oxides react with water to form bases:

Na2O + H2O → 2NaOH.

2.React with acidic oxides to form the corresponding salts

Na2O + SO3 → Na2SO4.

3.React with acids to form salt and water:

CuO + H2SO4 → CuSO4 + H2O.

4.React with amphoteric oxides:

Li2O + Al2O3 → 2LiAlO2.

Chemical properties of acid oxides

If the second element in the composition of oxides is a non-metal or a metal exhibiting a higher valence (usually 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. These are, for example, CO2, SO3, P2O5, N2O3, Cl2O5, Mn2O7, etc. They dissolve in water and alkalis, forming salt and water.

1.React with water to form acid:

SO3 + H2O → H2SO4.

But not all acidic oxides directly react with water (SiO2, etc.).

2.React with based oxides to form a salt:

CO2 + CaO → CaCO3

3.They react with alkalis to form salt and water:

CO2 + Ba(OH)2 → BaCO3 + H2O.

Chemical properties of amphoteric oxides

In this composition of the amphoteric oxide, there is an element that has amphoteric properties. Amphotericity is understood as the ability of compounds to exhibit acidic and basic properties depending on the conditions.

1.React with acids to form salt and water:

ZnO + 2HCl → ZnCl2 + H2O.

2.They react with solid alkalis (during fusion), forming as a result of the reaction a salt - sodium zincate and water:

ZnO + 2NaOH → Na2 ZnO2 + H2O.

Physical properties

Liquid (SO3, Mn2O7); Solid (K2O, Al2O3, P2O5); Gaseous (CO2, NO2, SO2).

You can get oxides with ...

The interaction of simple substances (with the exception of inert gases, gold and platinum) with oxygen:

2H2 + O2 → 2H2O

2Cu + O2 → 2CuO

When alkali metals (except lithium), as well as strontium and barium, are burned in oxygen, peroxides and superoxides are formed:

2Na + O2 → Na2O2

Roasting or combustion of binary compounds in oxygen:

4FeS2 + 11O2 → 2Fe2O3 + 8SO2

CS2 + 3O2 → CO2 + 2SO2

2PH3 + 4O2 → P2O5 + 3H2O

Thermal decomposition of salts:

CaCO3 → CaO + CO2

2FeSO4 → Fe2O3 + SO2 + SO3

Thermal decomposition of bases or acids:

2Al(OH)3 → Al2O3 + 3H2O

4HNO3 → 4NO2 + O2 + 2H2O

Oxidation of lower oxides to higher ones and reduction of higher ones to lower ones:

4FeO + O2 → 2Fe2O3

Fe2O3 + CO → 2FeO + CO2

The interaction of some metals with water at high temperature:

Zn + H2O → ZnO + H2

The interaction of salts with acid oxides during the combustion of coke with the release of a volatile oxide:

Ca3(PO4)2 + 3SiO2 + 5C(coke) → 3CaSiO3 + 2P+5CO

The interaction of metals with oxidizing acids:

Zn + 4HNO3(conc.) → Zn(NO3)2 + 2NO2 + 2H2O

Under the action of water-removing substances on acids and salts:

2KClO4 + H2SO4(conc) → K2SO4 + Cl2O7 + H2O

The interaction of salts of weak unstable acids with stronger acids:

NaHCO3 + HCl → NaCl + H2O + CO2

Nomenclature of oxides

The word "oxide" followed by the name chemical element in the genitive. When several oxides are formed, their names indicate its oxidation state with a Roman numeral in brackets immediately after the name. Other names of oxides are often used according to the number of oxygen atoms: if the oxide contains only one oxygen atom, then it is called monoxide, monoxide or nitrous if two - dioxide or dioxide, if three - then trioxide or trioxide etc.

These are complex substances consisting of two chemical elements, one of which is oxygen with an oxidation state (-2). General formula oxides: EmOn, where m- number of element atoms E, a n is the number of oxygen atoms. Oxides can be solid (sand SiO 2 , varieties of quartz), liquid (hydrogen oxide H 2 O), gaseous (carbon oxides: carbon dioxide CO 2 and carbon monoxide CO gases).

Nomenclature chemical compounds developed with the accumulation of factual material. At first, while the number of known compounds was small, widely used trivial names, not reflecting the composition, structure and properties of a substance, - minium Pb 3 O 4, litharge RIO, magnesia MgO iron oxide Fe 3 O 4, laughing gas N 2 O, white arsenic As 2 O 3 The trivial nomenclature was replaced by semi-systematic nomenclature - indications of the number of oxygen atoms in the compound were included in the name: nitrous- for lower oxide- for higher degrees of oxidation; anhydride- for acidic oxides.

At present, the transition to modern nomenclature is almost complete. According to international nomenclature, in the title oxide, the valency of the element should be indicated; for example, SO 2 - sulfur (IV) oxide, SO 3 - sulfur (VI) oxide, CrO - chromium (II) oxide, Cr 2 O 3 - chromium (III) oxide, CrO 3 - chromium (VI) oxide.

According to their chemical properties, oxides are divided into salt-forming and non-salt-forming.

Non-salt-forming such oxides are called that do not interact with either alkalis or acids and do not form salts. There are few of them, the composition includes non-metals.

Salt-forming Oxides are called those that react with acids or bases and form salt and water.

Among salt-forming oxides distinguish between oxides basic, acidic, amphoteric.

Basic oxides are oxides that correspond to bases. For example: CuO corresponds to the base Cu (OH) 2, Na 2 O - the base of NaOH, Cu 2 O - CuOH, etc.

Typical reactions of basic oxides

1. Basic oxide + acid \u003d salt + water (exchange reaction):

2. Basic oxide + acid oxide = salt (compound reaction):

3. Basic oxide + water = alkali (compound reaction):

Acid oxides are those oxides to which acids correspond. These are non-metal oxides: N 2 O 5 corresponds to HNO 3, SO 3 - H 2 SO 4, CO 2 - H 2 CO 3, P 2 O 5 - H 4 PO 4 as well as metal oxides with great value oxidation states: Cr 2 +6 O 3 corresponds to H 2 CrO 4, Mn 2 +7 O 7 - HMnO 4.

Typical reactions of acid oxides

1. Acid oxide + base \u003d salt + water (exchange reaction):

2. Acid oxide + basic oxide salt (compound reaction):

3. Acid oxide + water = acid (compound reaction):

Such a reaction is possible only if the acid oxide is soluble in water.

amphoteric called oxides, which, depending on the conditions, exhibit basic or acidic properties. These are ZnO, Al 2 O 3, Cr 2 O 3, V 2 O 5.

Amphoteric oxides do not combine directly with water.

Typical reactions of amphoteric oxides

1. Amphoteric oxide + acid \u003d salt + water (exchange reaction):

2. Amphoteric oxide + base \u003d salt + water or complex compound:

basic oxides. To main refer typical metal oxides, they correspond to hydroxides with the properties of bases.

Obtaining basic oxides

Oxidation of metals when heated in an oxygen atmosphere.

2Mg + O 2 \u003d 2MgO

2Cu + O 2 \u003d 2CuO

The method is not applicable for the production of alkali metal oxides. In reaction with oxygen, alkali metals usually give peroxides, so Na 2 O, K 2 O oxides are difficult to access.

Sulfide roasting

2CuS + 3O 2 = 2CuO + 2SO 2

4FeS 2 + 110 2 = 2Fe 2 O 3 + 8SO 2

The method is not applicable to active metal sulfides that oxidize to sulfates.

Decomposition of hydroxides

Cu(OH) 2 \u003d CuO + H 2 O

Thisthe method cannot be used to obtain oxides of alkali metals.

Decomposition of salts of oxygen-containing acids.

VaCO 3 \u003d BaO + CO 2

2Pb (NO 3) 2 \u003d 2PbO + 4N0 2 + O 2

4FeSO 4 \u003d 2Fe 2 O 3 + 4SO 2 + O 2

Decomposition is easily carried out for nitrates and carbonates, including basic salts.

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

Obtaining acid oxides

Acid oxides are represented by oxides of non-metals or transition metals in high oxidation states. They can be obtained by methods similar to those for basic oxides, for example:

1. 4P + 5O 2 \u003d 2P 2 O 5
2. 2ZnS + 3O 2 = 2ZnO + 2SO 2
3. K 2 Cr 2 O 7 + H 2 SO 4 \u003d 2CrO 3 ↓ + K 2 SO 4 + H 2 O
4. Na 2 SiO 3 + 2HCl \u003d 2NaCl + SiO 2 ↓ + H 2 O

Chemical properties acid oxides

1. Acid oxides interact with basic oxides and bases to form salts.

In this case, the rule is at least one of the oxides must correspond to a strong hydroxide (acid or alkali).

Acid oxides of strong and soluble acids interact with any basic oxides and bases:

SO 3 + CuO = CuSO 4

SO 3 + Cu (OH) 2 \u003d CuSO 4 + H 2 O

SO 3 + 2NaOH \u003d Na 2 SO 4 + H 2 O

SO 3 + Na 2 O \u003d Na 2 SO 4

Acid oxides of water-insoluble and unstable or volatile acids interact only with strong bases (alkalis) and their oxides. In this case, the formation of acidic and basic salts is possible, depending on the ratio and composition of the reagents.

For example , sodium oxide interacts with carbon monoxide (IV), and copper oxide (II), to which the insoluble base Cu (OH) 2 corresponds, practically does not interact with carbon monoxide (IV):

Na 2 O + CO 2 \u003d Na 2 CO 3

CuO + CO 2 ≠

2. Acid oxides react with water to form acids.

Exception — silicon oxide, which corresponds to insoluble silicic acid. Oxides, which correspond to unstable acids, as a rule, react with water reversibly and to a very small extent.

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

3. Acidic oxides react with amphoteric oxides and hydroxides to form a salt or salt and water.

Please note that, as a rule, only oxides of strong or medium acids interact with amphoteric oxides and hydroxides!

For example , Sulfuric anhydride (sulfur oxide (VI)) reacts with aluminum oxide and aluminum hydroxide to form a salt - aluminum sulfate:

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

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

But carbon monoxide (IV), which corresponds to weak carbonic acid, no longer interacts with aluminum oxide and aluminum hydroxide:

CO 2 + Al 2 O 3 ≠

CO 2 + Al (OH) 3 ≠

4. Acid oxides interact with salts of volatile acids.

The following rule applies: in the melt, less volatile acids and their oxides displace more volatile acids and their oxides from their salts.

For example , solid silicon oxide SiO 2 will displace the more volatile carbon dioxide from calcium carbonate when fused:

CaCO 3 + SiO 2 \u003d CaSiO 3 + CO 2

5. Acid oxides are capable of exhibiting oxidizing properties.

Usually, oxides of elements in the highest oxidation state - typical (SO 3, N 2 O 5, CrO 3, etc.). Strong oxidizing properties are also exhibited by some elements with an intermediate oxidation state (NO 2 and others).

6. Restorative properties.

Reducing properties, as a rule, are exhibited by oxides of elements in an intermediate oxidation state(CO, NO, SO 2, etc.). At the same time, they are oxidized to the highest or nearest stable oxidation state.

For example , sulfur oxide (IV) is oxidized by oxygen to sulfur oxide (VI):

2SO 2 + O 2 \u003d 2SO 3

Today we start with the most important classes inorganic compounds. Inorganic substances are divided by composition, as you already know, into simple and complex.

Complex inorganic substances are divided into four classes: oxides, acids, bases, salts. We start with the oxide class.

OXIDES

oxides - these are complex substances consisting of two chemical elements, one of which is oxygen, with a valence equal to 2. Only one chemical element - fluorine, combining with oxygen, forms not an oxide, but oxygen fluoride OF 2.
They are called simply - "oxide + element name" (see table). If the valence of a chemical element is variable, then it is indicated by a Roman numeral enclosed in parentheses after the name of the chemical element.

Classification of oxides

All oxides can be divided into two groups: salt-forming (basic, acidic, amphoteric) and non-salt-forming or indifferent.

1). Basic oxides are oxides that correspond to bases. The main oxides are oxides metals 1 and 2 groups, as well as metals side subgroups with valence I and II (except ZnO - zinc oxide and BeO – beryllium oxide):

2). Acid oxides are oxides to which acids correspond. Acid oxides are non-metal oxides (except for non-salt-forming - indifferent), as well as metal oxides side subgroups with valency from V before VII (For example, CrO 3 is chromium (VI) oxide, Mn 2 O 7 is manganese (VII) oxide):

3). Amphoteric oxides are oxides, which correspond to bases and acids. These include metal oxides main and secondary subgroups with valence III , sometimes IV , as well as zinc and beryllium (For example, BeO, ZnO, Al 2 O 3, Cr 2 O 3).

4). Non-salt-forming oxides are oxides that are indifferent to acids and bases. These include non-metal oxides with valence I and II (For example, N 2 O, NO, CO).

Conclusion: the nature of the properties of oxides primarily depends on the valency of the element.

For example, chromium oxides:

CrO(II- main);

Cr 2 O 3 (III- amphoteric);

CrO 3 (VII- acid).

Classification of oxides

(by solubility in water)

Complete the tasks:

1. Write separately chemical formulas salt-forming acidic and basic oxides.

NaOH, AlCl 3 , K 2 O, H 2 SO 4 , SO 3 , P 2 O 5 , HNO 3 , CaO, CO.

2. Substances are given : CaO, NaOH, CO 2 , H 2 SO 3 , CaCl 2 , FeCl 3 , Zn(OH) 2 , N 2 O 5 , Al 2 O 3 , Ca(OH) 2 , CO 2 , N 2 O, FeO, SO 3 , Na 2 SO 4 , ZnO, CaCO 3 , Mn 2 O 7 , CuO, KOH, CO, Fe(OH) 3

Obtaining oxides

Simulator "Interaction of oxygen with simple substances"

Physical properties of oxides

At room temperature, most oxides are solids (CaO, Fe 2 O 3, etc.), some are liquids (H 2 O, Cl 2 O 7, etc.) and gases (NO, SO 2, etc.).

Chemical properties of oxides

Application of oxides

Some oxides do not dissolve in water, but many react with water to combine:

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

CaO + H 2 O = Ca( Oh) 2

The result is often very desirable and useful compounds. For example, H 2 SO 4 - sulphuric acid, Ca(OH) 2 - slaked lime etc.

If oxides are insoluble in water, then people skillfully use this property as well. For example, zinc oxide ZnO is a white substance, therefore it is used to prepare white oil paint(zinc white). Since ZnO is practically insoluble in water, any surface can be painted with zinc white, including those that are exposed to atmospheric precipitation. Insolubility and non-toxicity make it possible to use this oxide in the manufacture of cosmetic creams and powders. Pharmacists make it an astringent and drying powder for external use.

Same valuable properties has titanium oxide (IV) - TiO 2. He also has a handsome White color and is used for the manufacture of titanium white. TiO 2 is insoluble not only in water, but also in acids; therefore, coatings made of this oxide are particularly stable. This oxide is added to plastic to give it a white color. It is part of the enamels for metal and ceramic utensils.

Chromium oxide (III) - Cr 2 O 3 - very strong crystals of dark green color, insoluble in water. Cr 2 O 3 is used as a pigment (paint) in the manufacture of decorative green glass and ceramics. The well-known GOI paste (short for the name “State Optical Institute”) is used for grinding and polishing optics, metal products in jewelry.

Tasks for fixing

1. Write down separately the chemical formulas of salt-forming acidic and basic oxides.

NaOH, AlCl 3 , K 2 O, H 2 SO 4 , SO 3 , P 2 O 5 , HNO 3 , CaO, CO.

2. Substances are given : CaO, NaOH, CO 2 , H 2 SO 3 , CaCl 2 , FeCl 3 , Zn(OH) 2 , N 2 O 5 , Al 2 O 3 , Ca(OH) 2 , CO 2 , N 2 O, FeO, SO 3 , Na 2 SO 4 , ZnO, CaCO 3 , Mn 2 O 7 , CuO, KOH, CO, Fe(OH) 3

Select from the list: basic oxides, acidic oxides, indifferent oxides, amphoteric oxides and name them.

3. Finish UCR, indicate the type of reaction, name the reaction products

Na 2 O + H 2 O =

N 2 O 5 + H 2 O =

CaO + HNO 3 =

NaOH + P 2 O 5 \u003d

K 2 O + CO 2 \u003d

Cu (OH) 2 \u003d? +?

4. Carry out the transformations according to the scheme:

1) K → K 2 O → KOH → K 2 SO 4

2) S → SO 2 → H 2 SO 3 → Na 2 SO 3

3) P → P 2 O 5 → H 3 PO 4 → K 3 PO 4