All typical properties of acid oxides. Oxides: classification and chemical properties

Before we start talking about the chemical properties of oxides, we need to remember that all oxides are divided into 4 types, namely basic, acidic, amphoteric and non-salt-forming. In order to determine the type of any oxide, first of all you need to understand whether it is a metal or non-metal oxide in front of you, and then use the algorithm (you need to learn it!) presented in the following table:

In addition to the types of oxides indicated above, we will also introduce two more subtypes of basic oxides, based on their chemical activity, namely active basic oxides And low-active basic oxides.

• TO active basic oxides We include oxides of alkali and alkaline earth metals (all elements of groups IA and IIA, except hydrogen H, beryllium Be and magnesium Mg). For example, Na 2 O, CaO, Rb 2 O, SrO, etc.
• TO low-active basic oxides we will include all the main oxides that are not included in the list active basic oxides. For example, FeO, CuO, CrO, etc.

It is logical to assume that active basic oxides often enter into reactions that low-active ones do not.
It should be noted that despite the fact that water is actually an oxide of a non-metal (H 2 O), its properties are usually considered in isolation from the properties of other oxides. This is due to its specifically huge distribution in the world around us, and therefore in most cases water is not a reagent, but a medium in which countless chemical reactions can take place. However, it often takes a direct part in various transformations, in particular, some groups of oxides react with it.

Which oxides react with water?

Of all the oxides with water react only:
1) all active basic oxides (oxides of alkali metal and alkali metal);
2) all acid oxides, except silicon dioxide (SiO 2);

those. From the above it follows that with water exactly don't react:
1) all low-active basic oxides;
2) all amphoteric oxides;
3) non-salt-forming oxides (NO, N 2 O, CO, SiO).

The ability to determine which oxides can react with water even without the ability to write the corresponding reaction equations already allows you to get points for some questions in the test part of the Unified State Exam.

Now let's figure out how certain oxides react with water, i.e. Let's learn to write the corresponding reaction equations.

Active basic oxides, reacting with water, form their corresponding hydroxides. Recall that the corresponding metal oxide is a hydroxide that contains the metal in the same oxidation state as the oxide. So, for example, when the active basic oxides K +1 2 O and Ba +2 O react with water, their corresponding hydroxides K +1 OH and Ba +2 (OH) 2 are formed:

K2O + H2O = 2KOH– potassium hydroxide

BaO + H 2 O = Ba(OH) 2– barium hydroxide

All hydroxides corresponding to active basic oxides (alkaline metal and alkali metal oxides) belong to alkalis. Alkalis are all metal hydroxides that are highly soluble in water, as well as poorly soluble calcium hydroxide Ca(OH) 2 (as an exception).

The interaction of acidic oxides with water, as well as the reaction of active basic oxides with water, leads to the formation of the corresponding hydroxides. Only in the case of acidic oxides do they correspond not to basic ones, but to acidic hydroxides, more often called oxygen-containing acids. Let us recall that the corresponding acidic oxide is an oxygen-containing acid that contains an acid-forming element in the same oxidation state as in the oxide.

Thus, if we, for example, want to write down the equation for the interaction of the acidic oxide SO 3 with water, first of all we must remember the main sulfur-containing acids studied in the school curriculum. These are hydrogen sulfide H 2 S, sulfurous H 2 SO 3 and sulfuric H 2 SO 4 acids. Hydrogen sulfide acid H 2 S, as can be easily seen, is not oxygen-containing, so its formation during the interaction of SO 3 with water can be immediately excluded. Of the acids H 2 SO 3 and H 2 SO 4, only sulfuric acid H 2 SO 4 contains sulfur in the oxidation state +6, as in SO 3 oxide. Therefore, it is precisely this that will be formed in the reaction of SO 3 with water:

H 2 O + SO 3 = H 2 SO 4

Similarly, the oxide N 2 O 5, containing nitrogen in the oxidation state +5, reacting with water, forms nitric acid HNO 3, but in no case nitrous HNO 2, since in nitric acid the oxidation state of nitrogen is the same as in N 2 O 5 , is equal to +5, and in nitrogen - +3:

N +5 2 O 5 + H 2 O = 2HN +5 O 3

Interaction of oxides with each other

First of all, you need to clearly understand the fact that among salt-forming oxides (acidic, basic, amphoteric), reactions almost never occur between oxides of the same class, i.e. In the vast majority of cases, interaction is impossible:

1) basic oxide + basic oxide ≠

2) acid oxide + acid oxide ≠

3) amphoteric oxide + amphoteric oxide ≠

While interaction is almost always possible between oxides belonging to different types, i.e. almost always are leaking reactions between:

1) basic oxide and acidic oxide;

2) amphoteric oxide and acid oxide;

3) amphoteric oxide and basic oxide.

As a result of all such interactions, the product is always average (normal) salt.

Let us consider all these pairs of interactions in more detail.

As a result of the interaction:

Me x O y + acid oxide, where Me x O y – metal oxide (basic or amphoteric)

a salt is formed consisting of the metal cation Me (from the initial Me x O y) and the acid residue of the acid corresponding to the acid oxide.

As an example, let’s try to write down the interaction equations for the following pairs of reagents:

Na 2 O + P 2 O 5 And Al 2 O 3 + SO 3

In the first pair of reagents we see a basic oxide (Na 2 O) and an acidic oxide (P 2 O 5). In the second - amphoteric oxide (Al 2 O 3) and acidic oxide (SO 3).

As already mentioned, as a result of the interaction of a basic/amphoteric oxide with an acidic one, a salt is formed, consisting of a metal cation (from the original basic/amphoteric oxide) and an acidic residue of the acid corresponding to the original acidic oxide.

Thus, the interaction of Na 2 O and P 2 O 5 should form a salt consisting of Na + cations (from Na 2 O) and the acidic residue PO 4 3-, since the oxide P +5 2 O 5 corresponds to acid H 3 P +5 O4. Those. As a result of this interaction, sodium phosphate is formed:

3Na 2 O + P 2 O 5 = 2Na 3 PO 4- sodium phosphate

In turn, the interaction of Al 2 O 3 and SO 3 should form a salt consisting of Al 3+ cations (from Al 2 O 3) and the acidic residue SO 4 2-, since the oxide S +6 O 3 corresponds to acid H 2 S +6 O4. Thus, as a result of this reaction, aluminum sulfate is obtained:

Al 2 O 3 + 3SO 3 = Al 2 (SO 4) 3- aluminum sulfate

More specific is the interaction between amphoteric and basic oxides. These reactions are carried out at high temperatures, and their occurrence is possible due to the fact that the amphoteric oxide actually takes on the role of an acidic one. As a result of this interaction, a salt of a specific composition is formed, consisting of a metal cation forming the original basic oxide and an “acid residue”/anion, which includes the metal from the amphoteric oxide. The general formula of such an “acid residue”/anion can be written as MeO 2 x - , where Me is a metal from an amphoteric oxide, and x = 2 in the case of amphoteric oxides with a general formula of the form Me + 2 O (ZnO, BeO, PbO) and x = 1 – for amphoteric oxides with a general formula of the form Me +3 2 O 3 (for example, Al 2 O 3, Cr 2 O 3 and Fe 2 O 3).

Let's try to write down the interaction equations as an example

ZnO + Na 2 O And Al 2 O 3 + BaO

In the first case, ZnO is an amphoteric oxide with the general formula Me +2 O, and Na 2 O is a typical basic oxide. According to the above, as a result of their interaction, a salt should be formed, consisting of a metal cation forming a basic oxide, i.e. in our case, Na + (from Na 2 O) and the “acid residue”/anion with the formula ZnO 2 2-, since the amphoteric oxide has a general formula of the form Me + 2 O. Thus, the formula of the resulting salt, subject to the condition of electrical neutrality of one of its structural units (“molecules”) will look like Na 2 ZnO 2:

ZnO + Na 2 O = t o=> Na 2 ZnO 2

In the case of an interacting pair of reagents Al 2 O 3 and BaO, the first substance is an amphoteric oxide with the general formula of the form Me + 3 2 O 3, and the second is a typical basic oxide. In this case, a salt is formed containing a metal cation from the main oxide, i.e. Ba 2+ (from BaO) and the “acid residue”/anion AlO 2 - . Those. the formula of the resulting salt, subject to the condition of electrical neutrality of one of its structural units (“molecules”), will have the form Ba(AlO 2) 2, and the interaction equation itself will be written as:

Al 2 O 3 + BaO = t o=> Ba(AlO 2) 2

As we wrote above, the reaction almost always occurs:

Me x O y + acid oxide,

where Me x O y is either a basic or amphoteric metal oxide.

However, there are two “finicky” acid oxides to remember - carbon dioxide (CO 2) and sulfur dioxide (SO 2). Their “fastidiousness” lies in the fact that despite their obvious acidic properties, the activity of CO 2 and SO 2 is not enough for their interaction with low-active basic and amphoteric oxides. Of the metal oxides, they react only with active basic oxides(oxides of alkali metal and alkali metal). For example, Na 2 O and BaO, being active basic oxides, can react with them:

CO 2 + Na 2 O = Na 2 CO 3

SO 2 + BaO = BaSO 3

While the oxides CuO and Al 2 O 3, which are not related to active basic oxides, do not react with CO 2 and SO 2:

CO 2 + CuO ≠

CO 2 + Al 2 O 3 ≠

SO 2 + CuO ≠

SO 2 + Al 2 O 3 ≠

Interaction of oxides with acids

Basic and amphoteric oxides react with acids. In this case, salts and water are formed:

FeO + H 2 SO 4 = FeSO 4 + H 2 O

Non-salt-forming oxides do not react with acids at all, and acidic oxides do not react with acids in most cases.

When does an acidic oxide react with an acid?

When solving the multiple-choice part of the Unified State Exam, you should conditionally assume that acidic oxides do not react with either acidic oxides or acids, except in the following cases:

1) silicon dioxide, being an acidic oxide, reacts with hydrofluoric acid, dissolving in it. In particular, thanks to this reaction, glass can be dissolved in hydrofluoric acid. In the case of excess HF, the reaction equation has the form:

SiO 2 + 6HF = H 2 + 2H 2 O,

and in case of HF deficiency:

SiO 2 + 4HF = SiF 4 + 2H 2 O

2) SO 2, being an acidic oxide, easily reacts with hydrosulfide acid H 2 S like co-proportionation:

S +4 O 2 + 2H 2 S -2 = 3S 0 + 2H 2 O

3) Phosphorus (III) oxide P 2 O 3 can react with oxidizing acids, which include concentrated sulfuric acid and nitric acid of any concentration. In this case, the oxidation state of phosphorus increases from +3 to +5:

Interaction of oxides with metal hydroxides

Acidic oxides react with metal hydroxides, both basic and amphoteric. This produces a salt consisting of a metal cation (from the original metal hydroxide) and an acid residue corresponding to the acid oxide.

SO 3 + 2NaOH = Na 2 SO 4 + H 2 O

Acidic oxides, which correspond to polybasic acids, can form both normal and acid salts with alkalis:

CO 2 + 2NaOH = Na 2 CO 3 + H 2 O

CO 2 + NaOH = NaHCO 3

P 2 O 5 + 6KOH = 2K 3 PO 4 + 3H 2 O

P 2 O 5 + 4KOH = 2K 2 HPO 4 + H 2 O

P 2 O 5 + 2KOH + H 2 O = 2KH 2 PO 4

“Finicky” oxides CO 2 and SO 2, the activity of which, as already mentioned, is not enough for their reaction with low-active basic and amphoteric oxides, nevertheless, react with most of the corresponding metal hydroxides. More precisely, carbon dioxide and sulfur dioxide react with insoluble hydroxides in the form of their suspension in water. In this case, only the basic O natural salts called hydroxycarbonates and hydroxosulfites, and the formation of intermediate (normal) salts is impossible:

2Zn(OH) 2 + CO 2 = (ZnOH) 2 CO 3 + H 2 O(in solution)

2Cu(OH) 2 + CO 2 = (CuOH) 2 CO 3 + H 2 O(in solution)

However, carbon dioxide and sulfur dioxide do not react at all with metal hydroxides in the oxidation state +3, for example, such as Al(OH)3, Cr(OH)3, etc.

It should also be noted that silicon dioxide (SiO 2) is particularly inert, most often found in nature in the form of ordinary sand. This oxide is acidic, but among metal hydroxides it is capable of reacting only with concentrated (50-60%) solutions of alkalis, as well as with pure (solid) alkalis during fusion. In this case, silicates are formed:

2NaOH + SiO 2 = t o=> Na 2 SiO 3 + H 2 O

Amphoteric oxides from metal hydroxides react only with alkalis (hydroxides of alkali and alkaline earth metals). In this case, when the reaction is carried out in aqueous solutions, soluble complex salts are formed:

ZnO + 2NaOH + H 2 O = Na 2- sodium tetrahydroxozincate

BeO + 2NaOH + H 2 O = Na 2- sodium tetrahydroxoberyllate

Al 2 O 3 + 2NaOH + 3H 2 O = 2Na- sodium tetrahydroxyaluminate

Cr 2 O 3 + 6NaOH + 3H 2 O = 2Na 3- sodium hexahydroxochromate (III)

And when these same amphoteric oxides are fused with alkalis, salts are obtained consisting of an alkali or alkaline earth metal cation and an anion of the type MeO 2 x -, where x= 2 in the case of amphoteric oxide type Me +2 O and x= 1 for an amphoteric oxide of the form Me 2 +2 O 3:

ZnO + 2NaOH = t o=> Na 2 ZnO 2 + H 2 O

BeO + 2NaOH = t o=> Na 2 BeO 2 + H 2 O

Al 2 O 3 + 2NaOH = t o=> 2NaAlO 2 + H 2 O

Cr 2 O 3 + 2NaOH = t o=> 2NaCrO 2 + H 2 O

Fe 2 O 3 + 2NaOH = t o=> 2NaFeO 2 + H 2 O

It should be noted that salts obtained by fusing amphoteric oxides with solid alkalis can be easily obtained from solutions of the corresponding complex salts by evaporation and subsequent calcination:

Na 2 = t o=> Na 2 ZnO 2 + 2H 2 O

Na = t o=> NaAlO 2 + 2H 2 O

Interaction of oxides with medium salts

Most often, medium salts do not react with oxides.

However, you should learn the following exceptions to this rule, which are often encountered in the exam.

One of these exceptions is that amphoteric oxides, as well as silicon dioxide (SiO 2), when fused with sulfites and carbonates, displace sulfur dioxide (SO 2) and carbon dioxide (CO 2) gases from the latter, respectively. For example:

Al 2 O 3 + Na 2 CO 3 = t o=> 2NaAlO 2 + CO 2

SiO 2 + K 2 SO 3 = t o=> K 2 SiO 3 + SO 2

Also, reactions of oxides with salts can conditionally include the interaction of sulfur dioxide and carbon dioxide with aqueous solutions or suspensions of the corresponding salts - sulfites and carbonates, leading to the formation of acid salts:

Na 2 CO 3 + CO 2 + H 2 O = 2NaHCO 3

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

Also, sulfur dioxide, when passed through aqueous solutions or suspensions of carbonates, displaces carbon dioxide from them due to the fact that sulfurous acid is a stronger and more stable acid than carbonic acid:

K 2 CO 3 + SO 2 = K 2 SO 3 + CO 2

ORR involving oxides

Reduction of metal and non-metal oxides

Just as metals can react with solutions of salts of less active metals, displacing the latter in free form, metal oxides when heated are also able to react with more active metals.

Let us recall that the activity of metals can be compared either using the activity series of metals, or, if one or two metals are not in the activity series, by their position relative to each other in the periodic table: the lower and to the left the metal, the more active it is. It is also useful to remember that any metal from the AHM and ALP family will always be more active than a metal that is not a representative of ALM or ALP.

In particular, the aluminothermy method, used in industry to obtain such difficult-to-reduce metals as chromium and vanadium, is based on the interaction of a metal with the oxide of a less active metal:

Cr 2 O 3 + 2Al = t o=> Al 2 O 3 + 2Cr

During the aluminothermy process, a colossal amount of heat is generated, and the temperature of the reaction mixture can reach more than 2000 o C.

Also, the oxides of almost all metals located in the activity series to the right of aluminum can be reduced to free metals by hydrogen (H 2), carbon (C) and carbon monoxide (CO) when heated. For example:

Fe 2 O 3 + 3CO = t o=> 2Fe + 3CO 2

CuO+C= t o=> Cu + CO

FeO + H2 = t o=> Fe + H 2 O

It should be noted that if the metal can have several states of oxidation, incomplete reduction of the oxides is also possible if there is a lack of the reducing agent used. For example:

Fe 2 O 3 + CO =t o=> 2FeO + CO 2

4CuO + C = t o=> 2Cu 2 O + CO 2

Oxides of active metals (alkali, alkaline earth, magnesium and aluminum) with hydrogen and carbon monoxide don't react.

However, oxides of active metals react with carbon, but differently than oxides of less active metals.

Within the framework of the Unified State Examination program, in order not to be confused, it should be assumed that as a result of the reaction of oxides of active metals (up to Al inclusive) with carbon, the formation of free alkali metal, alkali metal, Mg, and Al is impossible. In such cases, metal carbide and carbon monoxide are formed. For example:

2Al 2 O 3 + 9C = t o=> Al 4 C 3 + 6CO

CaO + 3C = t o=> CaC 2 + CO

Oxides of nonmetals can often be reduced by metals to free nonmetals. For example, when heated, oxides of carbon and silicon react with alkali, alkaline earth metals and magnesium:

CO2 + 2Mg = t o=> 2MgO + C

SiO2 + 2Mg = t o=>Si + 2MgO

With an excess of magnesium, the latter interaction can also lead to the formation magnesium silicide Mg 2 Si:

SiO2 + 4Mg = t o=> Mg 2 Si + 2 MgO

Nitrogen oxides can be reduced relatively easily even with less active metals, such as zinc or copper:

Zn + 2NO = t o=> ZnO + N 2

NO 2 + 2Cu = t o=> 2CuO + N 2

Interaction of oxides with oxygen

In order to be able to answer the question of whether any oxide reacts with oxygen (O 2) in the tasks of the real Unified State Examination, you first need to remember that oxides that can react with oxygen (from those that you may come across in the exam itself) can form only chemical elements from the list:

Oxides of any other chemical elements found in the real Unified State Exam react with oxygen they won't (!).

For a more visual and convenient memorization of the list of elements listed above, in my opinion, the following illustration is convenient:

All chemical elements capable of forming oxides that react with oxygen (from those encountered on the exam)

First of all, among the listed elements, nitrogen N should be considered, because the ratio of its oxides to oxygen differs markedly from the oxides of other elements in the above list.

It should be clearly remembered that nitrogen can form five oxides in total, namely:

Of all nitrogen oxides, it can react with oxygen only NO. This reaction occurs very easily when NO is mixed with both pure oxygen and air. In this case, a rapid change in the color of the gas from colorless (NO) to brown (NO 2) is observed:

In order to answer the question - does any oxide of any other of the chemical elements listed above react with oxygen (i.e. WITH,Si, P, S, Cu, Mn, Fe, Cr) — First of all, you need to remember them basic oxidation state (CO). Here they are :

Next, you need to remember the fact that of the possible oxides of the above chemical elements, only those that contain the element in the minimum oxidation state among those indicated above will react with oxygen. In this case, the oxidation state of the element increases to the nearest positive value possible:

Today we begin our acquaintance with the most important classes of inorganic compounds. Inorganic substances are divided according to their 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 of 2. Only one chemical element - fluorine, when combined with oxygen, forms not an oxide, but oxygen fluoride OF 2.
They are simply called “oxide + name of the element” (see table). If the valence of a chemical element is variable, it is indicated by a Roman numeral enclosed in parentheses after the name of the chemical element.

Oxides classification

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

3). Amphoteric oxides- These 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– these are oxides 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);

CrO3(VII- acidic).

Oxides classification

(by solubility in water)

Complete the tasks:

1. Write out 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. Given substances : 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 form compounds:

SO 3 + H 2 O = H 2 SO 4

CaO + H 2 O = Ca( OH) 2

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

If oxides are insoluble in water, then people skillfully use this property. 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 precipitation. Insolubility and non-toxicity allow this oxide to be used in the manufacture of cosmetic creams and powders. Pharmacists make it into an astringent and drying powder for external use.

Titanium (IV) oxide – TiO 2 – has the same valuable properties. It also has a beautiful white color and is used to make titanium white. TiO 2 is insoluble not only in water, but also in acids, so coatings made from this oxide are especially stable. This oxide is added to plastic to give it a white color. It is part of enamels for metal and ceramic dishes.

Chromium (III) oxide - Cr 2 O 3 - very strong dark green crystals, 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 consolidation

1. Write out 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. Given substances : 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 give them names.

3. Complete the CSR, indicate the type of reaction, name the reaction products

Na 2 O + H 2 O =

N 2 O 5 + H 2 O =

CaO + HNO3 =

NaOH + P2O5 =

K 2 O + CO 2 =

Cu(OH) 2 = ? + ?

4. Carry out 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

In lesson 32 " Chemical properties of oxides" from the course " Chemistry for dummies“We will learn about all the chemical properties of acidic and basic oxides, consider what they react with and what is formed.

Since the chemical composition of acidic and basic oxides is different, they differ in their chemical properties.

1. Chemical properties of acid oxides

a) Interaction with water
You already know that the products of the interaction of oxides with water are called “hydroxides”:

Since the oxides that enter into this reaction are divided into acidic and basic, the hydroxides formed from them are also divided into acidic and basic. Thus, acidic oxides (except SiO2) react with water to form acidic hydroxides, which are oxygen-containing acids:

Each acidic oxide corresponds to an oxygen-containing acid, which is classified as acidic hydroxides. Despite the fact that silicon oxide SiO 2 does not react with water, the acid H 2 SiO 3 also corresponds to it, but it is obtained by other methods.

b) Interaction with alkalis
All acid oxides react with alkalis according to the general scheme:

In the resulting salt, the valency of the metal atoms is the same as in the original alkali. Besides, the salt contains the remainder of the acid that corresponds to the given acid oxide.

For example, if the acidic oxide CO 2 reacts, which corresponds to the acid H 2 CO3 CO3, whose valency, as you already know, is II:

If the acidic oxide N 2 O 5 enters into the reaction, which corresponds to the acid H NO 3(indicated in square brackets), then the resulting salt will contain the remainder of this acid - NO 3 with valence equal to I:

Since all acidic oxides react with alkalis to form salts and water, these oxides can be given another definition.

Acidic are called oxides that react with alkalis to form salts and water.

c) Reactions with basic oxides

Acidic oxides react with basic oxides to form salts according to the general scheme:

In the resulting salt, the valency of the metal atoms is the same as in the original basic oxide. It should be remembered that the salt contains the remainder of the acid that corresponds to the acid oxide that enters into the reaction. For example, if the acid oxide SO 3 reacts, which corresponds to the acid H 2 SO 4(indicated in square brackets), then the salt will include the remainder of this acid - SO 4, whose valency is II:

If the acidic oxide P 2 O 5 enters into the reaction, which corresponds to the acid H 3 RO 4, then the resulting salt will contain the remainder of this acid - PO 4 with a valence of III.

2. Chemical properties of basic oxides

a) Interaction with water

You already know that as a result of the interaction of basic oxides with water, basic hydroxides are formed, which are otherwise called bases:

These basic oxides include the following oxides: Li 2 O, Na 2 O, K 2 O, CaO, BaO.

When writing equations for the corresponding reactions, it should be remembered that the valence of metal atoms in the resulting base is equal to its valence in the original oxide.

Basic oxides formed by metals such as Cu, Fe, Cr do not react with water. The corresponding bases are obtained in other ways.

b) Interaction with acids

Almost all basic oxides react with acids to form salts according to the general scheme:

It should be remembered that in the resulting salt, the valency of the metal atoms is the same as in the original oxide, and the valency of the acid residue is the same as in the original acid.

Since all basic oxides react with acids to form salts and water, these oxides can be given another definition.

Main are called oxides that react with acids to form salts and water.

c) Interaction with acid oxides

Basic oxides react with acidic oxides to form salts according to the general scheme:

In the resulting salt, the valency of the metal atoms is the same as in the original basic oxide. In addition, you should remember that the salt contains the remainder of the acid that corresponds to the acid oxide that reacts. For example, if the acidic oxide N2O5 reacts, which corresponds to the acid H NO 3, then the salt will contain the remainder of this acid - NO 3, whose valency, as you already know, is I.

Since the acidic and basic oxides we have considered form salts as a result of various reactions, they are called salt-forming. There is, however, a small group of oxides that do not form salts in similar reactions, which is why they are called non-salt-forming.

Brief conclusions of the lesson:

1. All acidic oxides react with alkalis to form salts and water.
2. All basic oxides react with acids to form salts and water.
3. Acidic and basic oxides are salt-forming. Non-salt-forming oxides - CO, N 2 O, NO.
4. Bases and oxygen-containing acids are hydroxides.

Hope lesson 32" Chemical properties of oxides"was clear and informative. If you have any questions, write them in the comments.

Properties of oxides

Oxides- these are complex chemical substances, which are chemical compounds of simple elements with oxygen. They happen salt-forming And non-salt forming. In this case, there are 3 types of salt-forming agents: main(from the word "foundation"), acidic And amphoteric.
An example of oxides that do not form salts are: NO (nitric oxide) - is a colorless, odorless gas. It is formed during a thunderstorm in the atmosphere. CO (carbon monoxide) is an odorless gas produced by the combustion of coal. It is commonly called carbon monoxide. There are other oxides that do not form salts. Now let's take a closer look at each type of salt-forming oxides.

Basic oxides

Basic oxides- These are complex chemical substances related to oxides that form salts upon chemical reaction with acids or acidic oxides and do not react with bases or basic oxides. For example, the main ones include the following:
K 2 O (potassium oxide), CaO (calcium oxide), FeO (ferrous oxide).

Let's consider chemical properties of oxides with examples

1. Interaction with water:
- interaction with water to form a base (or alkali)

CaO+H 2 O → Ca(OH) 2 (a well-known lime slaking reaction, which releases a large amount of heat!)

2. Interaction with acids:
- interaction with acid to form salt and water (salt solution in water)

CaO+H 2 SO 4 → CaSO 4 + H 2 O (Crystals of this substance CaSO 4 are known to everyone under the name “gypsum”).

3. Interaction with acid oxides: salt formation

CaO+CO 2 → CaCO 3 (Everyone knows this substance - ordinary chalk!)

Acidic oxides

Acidic oxides- these are complex chemical substances related to oxides that form salts upon chemical interaction with bases or basic oxides and do not interact with acidic oxides.

Examples of acidic oxides can be:

CO 2 (well-known carbon dioxide), P 2 O 5 - phosphorus oxide (formed by the combustion of white phosphorus in air), SO 3 - sulfur trioxide - this substance is used to produce sulfuric acid.

Chemical reaction with water

CO 2 +H 2 O → H 2 CO 3 - this substance is carbonic acid - one of the weak acids, it is added to carbonated water to create gas “bubbles”. With increasing temperature, the solubility of gas in water decreases, and its excess comes out in the form of bubbles.

Reaction with alkalis (bases):

CO 2 +2NaOH→ Na 2 CO 3 +H 2 O- the resulting substance (salt) is widely used in the household. Its name - soda ash or washing soda - is an excellent detergent for burnt pots, grease, and burnt marks. I do not recommend working with bare hands!

Reaction with basic oxides:

CO 2 +MgO→ MgCO 3 - the resulting salt is magnesium carbonate - also called “bitter salt”.

Amphoteric oxides

Amphoteric oxides- these are complex chemical substances, also related to oxides, which form salts during chemical interaction with acids (or acid oxides) and grounds (or basic oxides). The most common use of the word "amphoteric" in our case refers to metal oxides.

Example amphoteric oxides may be:

ZnO - zinc oxide (white powder, often used in medicine for making masks and creams), Al 2 O 3 - aluminum oxide (also called “alumina”).

The chemical properties of amphoteric oxides are unique in that they can enter into chemical reactions with both bases and acids. For example:

Reaction with acid oxide:

ZnO+H 2 CO 3 → ZnCO 3 + H 2 O - The resulting substance is a solution of the salt “zinc carbonate” in water.

Reaction with bases:

ZnO+2NaOH→ Na 2 ZnO 2 +H 2 O - the resulting substance is a double salt of sodium and zinc.

Obtaining oxides

Obtaining oxides produced in various ways. This can happen through physical and chemical means. The simplest way is the chemical interaction of simple elements with oxygen. For example, the result of the combustion process or one of the products of this chemical reaction are oxides. For example, if a hot iron rod, and not only iron (you can take zinc Zn, tin Sn, lead Pb, copper Cu - basically whatever is at hand) is placed in a flask with oxygen, then a chemical reaction of iron oxidation will occur, which accompanied by a bright flash and sparks. The reaction product will be black iron oxide powder FeO:

2Fe+O 2 → 2FeO

Chemical reactions with other metals and non-metals are completely similar. Zinc burns in oxygen to form zinc oxide

2Zn+O 2 → 2ZnO

Coal combustion is accompanied by the formation of two oxides at once: carbon monoxide and carbon dioxide.

2C+O 2 → 2CO - formation of carbon monoxide.

C+O 2 → CO 2 - formation of carbon dioxide. This gas is formed if there is more than enough oxygen, that is, in any case, the reaction first occurs with the formation of carbon monoxide, and then the carbon monoxide is oxidized, turning into carbon dioxide.

Obtaining oxides can be done in another way - through a chemical decomposition reaction. For example, to obtain iron oxide or aluminum oxide, it is necessary to calcinate the corresponding bases of these metals over a fire:

Fe(OH) 2 → FeO+H 2 O

Solid aluminum oxide - mineral corundum Iron(III) oxide. The surface of the planet Mars is reddish-orange in color due to the presence of iron (III) oxide in the soil. Solid aluminum oxide - corundum

2Al(OH) 3 → Al 2 O 3 +3H 2 O,
as well as during the decomposition of individual acids:

H 2 CO 3 → H 2 O+CO 2 - decomposition of carbonic acid

H 2 SO 3 → H 2 O+SO 2 - decomposition of sulfurous acid

Obtaining oxides can be made from metal salts with strong heating:

CaCO 3 → CaO+CO 2 - calcination of chalk produces calcium oxide (or quicklime) and carbon dioxide.

2Cu(NO 3) 2 → 2CuO + 4NO 2 + O 2 - in this decomposition reaction two oxides are obtained at once: copper CuO (black) and nitrogen NO 2 (it is also called brown gas because of its really brown color).

Another way in which oxides can be produced is through redox reactions.

Cu + 4HNO 3 (conc.) → Cu(NO 3) 2 + 2NO 2 + 2H 2 O

S + 2H 2 SO 4 (conc.) → 3SO 2 + 2H 2 O

Chlorine oxides

The following are known chlorine oxides: Cl 2 O, ClO 2, Cl 2 O 6, Cl 2 O 7. All of them, with the exception of Cl 2 O 7, are yellow or orange in color and are not stable, especially ClO 2, Cl 2 O 6. All chlorine oxides are explosive and are very strong oxidizing agents.

Reacting with water, they form the corresponding oxygen-containing and chlorine-containing acids:

So, Cl 2 O - acid chlorine oxide hypochlorous acid.

Cl 2 O + H 2 O → 2HClO - Hypochlorous acid

ClO2 - acid chlorine oxide hypochlorous and hypochlorous acid, since during a chemical reaction with water it forms two of these acids at once:

ClO 2 + H 2 O→ HClO 2 + HClO 3

Cl 2 O 6 - too acid chlorine oxide perchloric and perchloric acids:

Cl 2 O 6 + H 2 O → HClO 3 + HClO 4

And finally, Cl 2 O 7 - a colorless liquid - acid chlorine oxide perchloric acid:

Cl 2 O 7 + H 2 O → 2HClO 4

Nitrogen oxides

Nitrogen is a gas that forms 5 different compounds with oxygen - 5 nitrogen oxides. Namely:

N2O- nitric oxide. Its other name is known in medicine as laughing gas or nitrous oxide- It is colorless, sweetish and pleasant to the taste of gas.
- NO - nitrogen monoxide- a colorless, odorless, tasteless gas.
- N 2 O 3 - nitrous anhydride- colorless crystalline substance
- NO 2 - nitrogen dioxide. Its other name is brown gas- the gas really has a brownish-brown color
- N 2 O 5 - nitric anhydride- blue liquid, boiling at a temperature of 3.5 0 C

Of all these listed nitrogen compounds, NO - nitrogen monoxide and NO 2 - nitrogen dioxide are of greatest interest in industry. Nitrogen monoxide(NO) and nitrous oxide N 2 O does not react with water or alkalis. (N 2 O 3) when reacting with water, forms a weak and unstable nitrous acid HNO 2, which in air gradually turns into a more stable chemical substance, nitric acid. Let's look at some chemical properties of nitrogen oxides:

Reaction with water:

2NO 2 + H 2 O → HNO 3 + HNO 2 - 2 acids are formed at once: nitric acid HNO 3 and nitrous acid.

Reaction with alkali:

2NO 2 + 2NaOH → NaNO 3 + NaNO 2 + H 2 O - two salts are formed: sodium nitrate NaNO 3 (or sodium nitrate) and sodium nitrite (a salt of nitrous acid).

Reaction with salts:

2NO 2 + Na 2 CO 3 → NaNO 3 + NaNO 2 + CO 2 - two salts are formed: sodium nitrate and sodium nitrite, and carbon dioxide is released.

Nitrogen dioxide (NO 2) is obtained from nitrogen monoxide (NO) using a chemical reaction combining with oxygen:

2NO + O 2 → 2NO 2

Iron oxides

Iron forms two oxide: FeO - iron oxide(2-valent) - black powder, which is obtained by reduction iron oxide(3-valent) carbon monoxide by the following chemical reaction:

Fe 2 O 3 +CO→ 2FeO+CO 2

This is a basic oxide that reacts easily with acids. It has reducing properties and quickly oxidizes into iron oxide(3-valent).

4FeO +O 2 → 2Fe 2 O 3

Iron oxide(3-valent) - red-brown powder (hematite), which has amphoteric properties (can interact with both acids and alkalis). But the acidic properties of this oxide are so weakly expressed that it is most often used as basic oxide.

There are also so-called mixed iron oxide Fe 3 O 4 . It is formed when iron burns, conducts electricity well and has magnetic properties (it is called magnetic iron ore or magnetite). If iron burns, then as a result of the combustion reaction, scale is formed, consisting of two oxides: iron oxide(III) and (II) valence.

Sulfur oxide

Sulfur oxide SO 2 - or sulfur dioxide refers to acid oxides, but does not form acid, although it is perfectly soluble in water - 40 liters of sulfur oxide in 1 liter of water (for the convenience of drawing up chemical equations, such a solution is called sulfurous acid).

Under normal circumstances, it is a colorless gas with a pungent and suffocating odor of burnt sulfur. At a temperature of only -10 0 C it can be converted into a liquid state.

In the presence of a catalyst - vanadium oxide (V 2 O 5) sulfur oxide attaches oxygen and turns into sulfur trioxide

2SO 2 +O 2 → 2SO 3

Dissolved in water sulfur dioxide- sulfur oxide SO2 - oxidizes very slowly, as a result of which the solution itself turns into sulfuric acid

If sulfur dioxide pass an alkali, for example, sodium hydroxide, through a solution, then sodium sulfite is formed (or hydrosulfite - depending on how much alkali and sulfur dioxide you take)

NaOH + SO 2 → NaHSO 3 - sulfur dioxide taken in excess

2NaOH + SO 2 → Na 2 SO 3 + H 2 O

If sulfur dioxide does not react with water, then why does its aqueous solution give an acidic reaction?! Yes, it does not react, but it itself oxidizes in water, adding oxygen to itself. And it turns out that free hydrogen atoms accumulate in water, which give an acidic reaction (you can check with some indicator!)

Oxides, their classification and properties are the basis of such an important science as chemistry. They begin to be studied in the first year of studying chemistry. In such exact sciences as mathematics, physics and chemistry, all the material is interconnected, which is why failure to master the material entails a lack of understanding of new topics. Therefore, it is very important to understand the topic of oxides and fully understand it. We will try to talk about this in more detail today.

What are oxides?

Oxides, their classification and properties are what needs to be understood first. So, what are oxides? Do you remember this from school?

Oxides (or oxides) are binary compounds that contain atoms of an electronegative element (less electronegative than oxygen) and oxygen with an oxidation state of -2.

Oxides are incredibly common substances on our planet. Examples of oxide compounds include water, rust, some dyes, sand, and even carbon dioxide.

Formation of oxides

Oxides can be obtained in a variety of ways. The formation of oxides is also studied by such a science as chemistry. Oxides, their classification and properties - this is what scientists need to know in order to understand how this or that oxide was formed. For example, they can be obtained by directly combining an oxygen atom (or atoms) with a chemical element - this is the interaction of chemical elements. However, there is also indirect formation of oxides, this is when oxides are formed by the decomposition of acids, salts or bases.

Oxides classification

Oxides and their classification depend on how they are formed. According to their classification, oxides are divided into only two groups, the first of which is salt-forming, and the second is non-salt-forming. So, let's take a closer look at both groups.

Salt-forming oxides are a fairly large group, which is divided into amphoteric, acidic and basic oxides. As a result of any chemical reaction, salt-forming oxides form salts. As a rule, the composition of salt-forming oxides includes elements of metals and non-metals, which form acids as a result of a chemical reaction with water, but when interacting with bases they form the corresponding acids and salts.

Non-salt-forming oxides are those oxides that do not form salts as a result of a chemical reaction. Examples of such oxides include carbon.

Amphoteric oxides

Oxides, their classification and properties are very important concepts in chemistry. The composition of salt-forming compounds includes amphoteric oxides.

Amphoteric oxides are oxides that can exhibit basic or acidic properties, depending on the conditions of chemical reactions (they exhibit amphotericity). Such oxides are formed by transition metals (copper, silver, gold, iron, ruthenium, tungsten, rutherfordium, titanium, yttrium and many others). Amphoteric oxides react with strong acids, and as a result of a chemical reaction they form salts of these acids.

Acidic oxides

Or anhydrides are oxides that exhibit and also form oxygen-containing acids in chemical reactions. Anhydrides are always formed by typical nonmetals, as well as by some transition chemical elements.

Oxides, their classification and chemical properties are important concepts. For example, acidic oxides have completely different chemical properties from amphoteric oxides. For example, when an anhydride reacts with water, a corresponding acid is formed (the exception is SiO2 - Anhydrides react with alkalis, and as a result of such reactions water and soda are released. When reacting with, a salt is formed.

Basic oxides

Basic (from the word "base") oxides are oxides of chemical elements of metals with oxidation states +1 or +2. These include alkali and alkaline earth metals, as well as the chemical element magnesium. Basic oxides differ from others in that they are the ones that are able to react with acids.

Basic oxides interact with acids, unlike acidic oxides, as well as with alkalis, water, and other oxides. As a result of these reactions, salts are usually formed.

Properties of oxides

If you carefully study the reactions of various oxides, you can independently draw conclusions about what chemical properties the oxides are endowed with. The common chemical property of absolutely all oxides is the redox process.

But nevertheless, all oxides are different from each other. The classification and properties of oxides are two interrelated topics.

Non-salt-forming oxides and their chemical properties

Non-salt-forming oxides are a group of oxides that exhibit neither acidic, basic, nor amphoteric properties. As a result of chemical reactions with non-salt-forming oxides, no salts are formed. Previously, such oxides were not called non-salt-forming, but indifferent and indifferent, but such names do not correspond to the properties of non-salt-forming oxides. According to their properties, these oxides are quite capable of chemical reactions. But there are very few non-salt-forming oxides; they are formed by monovalent and divalent nonmetals.

From non-salt-forming oxides, salt-forming oxides can be obtained as a result of a chemical reaction.

Nomenclature

Almost all oxides are usually called this way: the word “oxide”, followed by the name of the chemical element in the genitive case. For example, Al2O3 is aluminum oxide. In chemical language, this oxide reads like this: aluminum 2 o 3. Some chemical elements, such as copper, can have several degrees of oxidation; accordingly, the oxides will also be different. Then CuO oxide is copper (two) oxide, that is, with an oxidation degree of 2, and Cu2O oxide is copper (three) oxide, which has an oxidation degree of 3.

But there are other names for oxides, which are distinguished by the number of oxygen atoms in the compound. Monoxides or monoxides are those oxides that contain only one oxygen atom. Dioxides are those oxides that contain two oxygen atoms, which are indicated by the prefix “di”. Trioxides are those oxides that already contain three oxygen atoms. Names such as monoxide, dioxide and trioxide are already outdated, but are often found in textbooks, books and other aids.

There are also so-called trivial names for oxides, that is, those that have developed historically. For example, CO is the oxide or monoxide of carbon, but even chemists most often call this substance carbon monoxide.

So, an oxide is a compound of oxygen with a chemical element. The main science that studies their formation and interactions is chemistry. Oxides, their classification and properties are several important topics in the science of chemistry, without understanding which it is impossible to understand everything else. Oxides are gases, minerals, and powders. Some oxides are worth knowing in detail not only for scientists, but also for ordinary people, because they can even be dangerous to life on this earth. Oxides are a very interesting and quite easy topic. Oxide compounds are very common in everyday life.