The interaction of water with basic and acidic oxides. Main oxides. Decomposition of hydroxides and salts

Oxides, their classification and properties are the basis of such an important science as chemistry. They are beginning to be studied in the first year of chemistry. In such accurate sciences, such as mathematics, physics and chemistry, the entire material is interconnected, which is why the failure of the material entails a misunderstanding of new topics. Therefore, it is very important to understand the theme of oxides and completely navigate it. We are talking about this today and will try to talk in more detail.

What is oxides?

Oxides, their classification and properties are what you need to understand paramount. So, what is oxides? You remember this from school program?

Oxides (or oxyls) - binary compounds, which includes the atoms of the electronegative element (less electronegative than oxygen) and oxygen with oxidation -2.

Oxides are incredibly common in our planet substance. Examples of oxide compound: water, rust, some dyes, sand and even carbon dioxide.

Education oxides

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

Classification of oxides

Oxides and their classification depends on how they were formed. According to its classification, oxides are divided into just two groups, the first of which is salted, and the second uncoupled. So, consider in more detail both groups.

Shaft-forming oxides are a rather large group that is divided into amphoteric, acidic and main 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, as a result of a chemical reaction with water, form acids, but when reacting with bases, appropriate acids and salts form.

Cutting oxides are such oxides, which, as a result of a chemical reaction, do not form salts. Examples of such oxides can also be carbon.

Amphoteric oxides

Oxides, their classification and properties are very important in chemistry concepts. The composition of the saline includes amphoteric oxides.

Amphoteric oxides are such oxides that can exhibit basic or acid properties, depending on the conditions chemical reactions (Exploid amphoterity). Such oxides are formed (copper, silver, gold, iron, ruthenium, tungsten, rutfords, 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.

Acid oxides

Or anhydrides are such oxides, which in chemical reactions show and form oxygen-containing acids. Anhydrides are always formed typical non-metals, as well as some transition chemical elements.

Oxides, their classification and chemical properties are important concepts. For example, in acid oxides, chemical properties differ completely from amphoteric. For example, when anhydride interacts with water, an appropriate acid is formed (an exception is SiO2 - anhydrides interact with alkalis, and as a result of such reactions, water and soda is distinguished. When interacting with a salt forms.

Main oxides

The main (from the word "base") oxides are oxides of the chemical elements of metals with oxidation degrees +1 or +2. These include alkaline, alkaline earth metals, as well as the chemical element of magnesium. The main oxides differ from others by exactly what they are capable of reacting with acids.

The main oxides interact with acids, in contrast to acidic oxides, as well as with alkalis, water, other oxides. As a result of these reactions, salts are usually formed.

Properties of oxide

If you carefully examine the reactions of different oxides, you can independently draw conclusions about what chemical properties of the oxyls are endowed. The total chemical property is absolutely all oxides in the redox process.

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

Non-forming oxides and their chemical properties

Non-forming oxides are such a group of oxides that does not show any acid nor basic nor amphoteric properties. As a result of chemical reactions with non-forming oxides, no salts are formed. Previously, such oxides were not called non-forming, but indifferent and indiffin, but such names do not correspond to the properties of non-forming oxides. In its properties, these oxyls are completely capable of chemical reactions. But there are very few inconsistent oxides, they are formed monovalent and bivalent non-metals.

Slate oxides can be obtained from non-forming oxides as a result of a chemical reaction.

Nomenclature

Almost all oxides are called this: the word "oxide", after which the name of the chemical element is followed in the parent. For example, Al2O3 is aluminum oxide. On the chemical language This oxide is read like this: aluminum 2 o 3. Some chemical elements, such as copper, can have several degrees of oxion, respectively, oxides will also be different. Then Cuo oxide is copper oxide (two), that is, with a degree of oxion 2, and Cu2O oxide is copper oxide (three), which has a degree of oxion 3.

But there are other names of oxides that are separated by the number in the compound of oxygen atoms. Monoxide or mono-oxide is called such oxides, which contain only one oxygen atom. Dioxides are called such oxyls, which contain two oxygen atoms, as reported by the "di" prefix. Trioxides are called such oxides in which there are already three oxygen atoms. Such items as monoxide, dioxide and trioxide are already outdated, but often found in textbooks, books and other benefits.

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

So, oxide is a compound of oxygen with a chemical element. The main science, which studies their education and interaction, is chemistry. Oxides, their classification and properties are a few important topics in the science of chemistry without understanding that everything else cannot be understood. Oxides are both gases, minerals and powders. Some oxides should know in detail not only scientists, but also to ordinary people, because they can even be dangerous to life on this earth. Oxides are a very interesting and easy-to-face theme. Compounds of oxides are very often found in everyday life.

Before you begin to talk about the chemical properties of oxides, it is necessary to recall that all oxides are divided into 4 types, namely basic, acid, amphoteric and non-forming. In order to determine the type of any oxide, first of all, it is necessary to understand - metal oxide or non-metallol in front of you, and then use the algorithm (it must be learned!), Presented in the following table:

In addition to the types of oxides mentioned above, we also introduce two more subtypes of the main oxides, based on their chemical activity, namely active main oxides and low-effective major oxides.

• TO active main oxides We will assign alkaline and alkaline earth metal oxides (all elements Ia and IIA groups, besides hydrogen H, Beryllium Be and magnesium Mg). For example, Na 2 O, Cao, Rb 2 O, sro, etc.
• TO a low-active main oxide Take all major oxides that did not hit the list active main oxides. For example, Feo, Cuo, Cro, etc.

It is logical to assume that the active main oxides often enter into those reactions in which the lowactive.

It should be noted that, despite the fact that actually water is non-metal (H 2 O) oxide, usually its properties are considered in the separation from the properties of other oxides. It is determined by it specifically tremendous 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 be carried out. However, it often accepts direct participation in various transformations, in particular, some groups of oxides react with it.

What oxides react with water?

Of all oxides with water react only:

1) all active main oxides (oxides Shchm and Schism);

2) all acid oxides, in addition to silicon dioxide (SiO 2);

those. From the above, it follows that with water accurately do not react:

1) all low-effective major oxides;

2) all amphoteric oxides;

3) non-forming oxides (NO, N 2 O, CO, SIO).

Note:

Magnesium oxide slowly reacts with water when boiling. Without severe heating, the MgO reaction with H 2 O does not proceed.

The ability to determine what oxides can react with water even without the ability to write the corresponding equations of reactions, already allowing points for some questions of the test part of the USE.

Now let's figure out how nevertheless, those or other oxides react with water, i.e. Let's learn how to write the appropriate equations of reactions.

Active main oxidesreacting with water, form the appropriate hydroxides. Recall that the corresponding metal oxide is such a hydroxide, which contains metal to the same oxidation, as oxide. For example, when reactions with water of active main oxides K +1 2 O and Ba +2 O are formed by the corresponding hydroxides K +1 OH and BA +2 (OH) 2:

K 2 O + H 2 O \u003d 2KOH - Potassium hydroxide

Bao + H 2 O \u003d BA (OH) 2 - Barium hydroxide

All hydroxides corresponding to the active main oxides (Oxides and Schism) belong to alkalis. Alkalis is called all metal hydroxides, as well as a low-soluble calcium hydroxide Ca (OH) 2 (as an exception).

The interaction of acid oxides with water in the same way as the reaction of the active main oxides with water leads to the formation of appropriate hydroxides. Only in the case of acid oxides, they are not compliant, and acidic hydroxides, more often called oxygen-containing acids. Recall that the corresponding acid oxide is such an oxygen-containing acid, which contains an acid-forming element to the same oxidation, as in oxide.

Thus, if we, for example, we want to write the equation of the interaction of acid oxide SO 3 with water, first of all, we must recall the basic studies under school program, sulfur-containing acids. Such are hydrogen sulfide H 2 S, sulfurous H 2 SO 3 and sulfur H 2 SO 4 acids. Celebrating acid H 2 S, as easy to notice, is not an oxygen-containing, therefore its formation in the interaction of SO 3 with water can be immediately excluded. From the acids of H 2 SO 3 and H 2 SO 4 sulfur to the degree of oxidation +6, as in SO 3 oxide, contains only sulfuric acid H 2 SO 4. Therefore, it is precisely it will be formed in the SO 3 reaction with water:

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

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

N +5 2 O 5 + H 2 O \u003d 2HN +5 O 3

An exception:

Nitrogen oxide (IV) (NO 2) is the nonmetal oxide into the degree of oxidation +4, i.e. In accordance with the algorithm described in the table at the very beginning of this chapter, it must be attributed to acid oxides. However, there is no acid that would contain nitrogen to the degree of oxidation +4.

2NO 2 + H 2 O \u003d HNO 2 + HNO 3

The interaction of oxides with each other

First of all, it is necessary to clearly assimilate the fact that among the salt-forming oxides (acidic, basic, amphoteric) almost never proceeds between the oxides of the same class, i.e. In the overwhelming majority of cases, it is impossible to interact:

1) main oxide + main oxide ≠

2) Acid oxide + acid oxide ≠

3) amphoteric oxide + amphoteric oxide ≠

At the time, there is almost always possible interaction between oxides relating to different types, i.e. almost always proceed Reactions between:

1) main oxide and acid oxide;

2) amphoteric oxide and acid oxide;

3) amphoteric oxide and main oxide.

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

Consider all the specified pairs of interactions in more detail.

As a result of interaction:

ME X O Y + acid oxide,where ME X O Y - metal oxide (main or amphoterous)

a salt forms, consisting of a metal cation of ME (from the original ME X O Y) and an acidic oxygen residue corresponding to acid oxide.

For example, let's try to record the interaction equations of the following steam reagents:

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

In the first pair of reagents, we see the main oxide (Na 2 O) and 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 the main / amphoteric oxide with an acidic acid, a salt consisting of a metal cation (from the initial main / amphoteric oxide) and an acidic oxygen residue corresponding to the original acid oxide is formed.

Thus, when Na 2 O and P 2 O 5 interacts, a salt consisting of Na + cations (from Na 2 O) and an acid residue PO 4 3-, since oxyid +5 2 O 5 corresponds to Acid H 3 P +5 O 4. Those. As a result of this interaction, sodium phosphate is formed:

3NA 2 O + P 2 O 5 \u003d 2NA 3 PO 4 - Sodium phosphate

In turn, when Al 2 O 3 and SO 3 interacts, a salt consisting of Al 3+ cations (from Al 2 O 3) and an acid residue SO 4 2-, since oxyid +6 O 3 corresponds to Acid H 2 S +6 O 4. Thus, as a result of this reaction, aluminum sulfate is obtained:

Al 2 O 3 + 3SO 3 \u003d Al 2 (SO 4) 3 - Aluminum sulfate

The interaction between amphoteric and main oxides is more specific. Reaction data is carried out at high temperatures, and their course is possible due to the fact that amphoteric oxide actually takes the role of acid. As a result of this interaction, a salt of a specific composition is formed, consisting of a metal cation forms the original base oxide and an "acid residue" / anion, which includes a metal from amphoteric oxide. Formula of such an "acid residue" / anion in general It can be written as MEO 2 x - where ME is a metal from amphoteric oxide, and x \u003d 2 in the case of amphoteric oxides with a general formula of the form ME +2 O (ZnO, BEO, PBO) and X \u003d 1 - for amphoteric oxides with general formula View 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 as an example of the interaction equation

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 - typical main oxide. According to the above, as a result of their interaction, salt should be formed, consisting of a metal cation forming the main oxide, i.e. In our case, Na + (from Na 2 O) and the "acid residue" / anion with the ZnO 2 2- formula, since the amphoteric oxide has a general formula of the form ME +2 O. Thus, the formula of the resulting salt, while compliance with the condition of the electronutrality of one structural Units ("molecules") will be viewed Na 2 ZnO 2:

Zno + Na 2 O \u003d t O.\u003d\u003e Na 2 ZnO 2

In the case of an interacting pair of Al 2 O 3 and Bao reagents, the first substance is an amphoteric oxide with a general formula of the form ME +3 2 O 3, and the second - typical main oxide. In this case, salt containing metal cation from the main oxide is formed, i.e. Ba 2+ (from Bao) and "Acid Residue" / Anion ALO 2 -. Those. The formula of the resulting salt, while observing the condition of the electronutrality of one structural unit ("molecules") will be viewed Ba (ALO 2) 2, and the interaction equation itself is recorded as:

Al 2 O 3 + Bao \u003d t O.\u003d\u003e Ba (ALO 2) 2

As we have already written above, the reaction is almost always flowing:

ME X O Y + acid oxide,

where ME X O y is either the main, or amphoter metal oxide.

However, two "perturbed" acid oxide should be remembered - carbon dioxide (CO 2) and sulfur gas (SO 2). The "assistant" is that despite the obvious acidic properties, the activity of CO 2 and SO 2 is not enough to interact with poorly important and amphoteric oxides. From metal oxides they react only with active main oxides (Schm and Schism oxides). So, for example, Na 2 O and Bao, being active main oxides, can react with them:

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

SO 2 + Bao \u003d Baso 3

While Cuo and Al 2 O 3 oxides, not related to the active main oxides, are not entering the reaction with CO 2 and SO 2:

CO 2 + CUO ≠

CO 2 + Al 2 O 3 ≠

SO 2 + Cuo ≠

SO 2 + Al 2 O 3 ≠

Acidity with acids

The basic and amphoteric oxides react with acids. At the same time, salts and water are formed:

Feo + H 2 SO 4 \u003d FESO 4 + H 2 O

Non-forming oxides are not reacting with acids in general, and acidic oxides do not react with acids in most cases.

When is it all the acidic oxide reacts with acid?

Solving part of the EGE with the answer options, you should relate to believe that acidic oxides do not react with acid oxides or with acids, with the exception of the following cases:

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

SiO 2 + 6HF \u003d H 2 + 2H 2 O,

and in the case of a lack of HF:

SiO 2 + 4HF \u003d SIF 4 + 2H 2 O

2) SO 2, being acidic oxide, easily reacts with hydrogen sulfide acid H 2 S by type combathege:

S +4 O 2 + 2H 2 S -2 \u003d 3S 0 + 2H 2 O

3) Phosphorus (III) oxide P 2 O 3 can react with oxidizing acids to which concentrated sulfuric acid and nitric acid of any concentration. At the same time, the degree of oxidation of phosphorus rises from the value of +3 to +5:

P 2 O 3	+	2H 2 SO 4	+	H 2 O.	=t O.=>	2SO 2.	+	2H 3 PO 4
		(conc.)

3 P 2 O 3	+	4HNO 3.	+	7 H 2 O.	=t O.=>	4no.	+	6 H 3 PO 4
		(RSC)

2hno 3.	+	3SO 2.	+	2H 2 O.	=t O.=>	3H 2 SO 4	+	2no.
(RSC)

The interaction of oxides with metals hydroxides

Acid oxides react with hydroxides of metals as basic and amphoteric. At the same time, salt forms, consisting of a metal cation (from the initial hydroxide of the metal) and the acid residue corresponding to acid oxide.

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

Acid oxides, which correspond to polypic acids, can form both normal and acidic salts with alkalis:

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

CO 2 + NaOH \u003d NaHCO 3

P 2 O 5 + 6KOH \u003d 2K 3 PO 4 + 3H 2 O

P 2 O 5 + 4KOH \u003d 2K 2 HPO 4 + H 2 O

P 2 O 5 + 2KOH + H 2 O \u003d 2KH 2 PO 4

"People's picky" oxides of CO 2 and SO 2, the activity of which, as already mentioned, is not enough for the flow of their reaction with low-effective basic and amphoteric oxides, however, they react with mostly the corresponding metal hydroxides. More precisely, carbon dioxide and sulfuric gases interact with insoluble hydroxides in the form of their suspension in water. At the same time, only the main aboutsalts called hydroxocarbonates and hydroxosulfitis, and the formation of medium (normal) salts is impossible:

2ZN (OH) 2 + CO 2 \u003d (ZnOH) 2 CO 3 + H 2 O (in solution)

2CU (OH) 2 + CO 2 \u003d (CuOH) 2 CO 3 + H 2 O (in solution)

However, with metals hydroxides in the degree of oxidation +3, for example, such as Al (OH) 3, CR (OH) 3, etc., carbon dioxide and sulfur gas do not react at all.

It should also be noted the special inertia of silicon dioxide (SiO 2), in nature the most common in the form of conventional sand. This oxide is acidic, however, from hydroxides of metals is able to react only with concentrated (50-60%) alkali solutions, as well as with pure (solid) alkalis when fusing. At the same time, silicates are formed:

2NAOH + SiO 2 \u003d t O.\u003d\u003e Na 2 SiO 3 + H 2 O

Amphoteric oxides from metals hydroxides react only with alkalis (alkaline and alkaline earth metal hydroxides). At the same time, during the reaction in aqueous solutions, soluble complex salts are formed:

Zno + 2NAOH + H 2 O \u003d Na 2 - Tetrahydroxyzinkat sodium

BEO + 2NAOH + H 2 O \u003d Na 2 - Tetrahydroxobyrillate sodium

Al 2 O 3 + 2NAOH + 3H 2 O \u003d 2NA - Tetrahydroxalulum of sodium

CR 2 O 3 + 6NAOH + 3H 2 O \u003d 2NA 3 - Hexagidroxchromate (III) sodium

And when fusing the same amphoteric oxides with alkalis, salts consisting of an alkali or alkaline earth metal cation and anion of the MEO 2 x view - where x. \u003d 2 In the case of amphoteric oxide of type ME +2 O and x. \u003d 1 for amphoteric oxide of the form ME 2 +2 O 3:

Zno + 2Naoh \u003d t O.\u003d\u003e Na 2 ZnO 2 + H 2 O

BEO + 2NAOH \u003d t O.\u003d\u003e Na 2 BEO 2 + H 2 O

Al 2 O 3 + 2Naoh \u003d t O.\u003d\u003e 2Naalo 2 + H 2 O

CR 2 O 3 + 2NAOH \u003d t O.\u003d\u003e 2nacro 2 + H 2 O

Fe 2 O 3 + 2NAOH \u003d t O.\u003d\u003e 2NAFEO 2 + H 2 O

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

Na 2 \u003d. t O.\u003d\u003e Na 2 ZnO 2 + 2H 2 O

Na \u003d. t O.\u003d\u003e Naalo 2 + 2H 2 O

Interaction of oxides with medium salts

Most often, middle salts with oxide react.

However, the following exceptions should be learned from this rule that are common in the exam.

One of these exceptions is that amphoteric oxides, as well as silicon dioxide (SiO 2), with their fusion with sulfite and carbonates, are displaced from the last sulfur (SO 2) and carbon dioxide (CO 2) gases, respectively. For example:

Al 2 O 3 + Na 2 CO 3 \u003d t O.\u003d\u003e 2Naalo 2 + CO 2

SiO 2 + K 2 SO 3 \u003d t O.\u003d\u003e K 2 SiO 3 + SO 2

Also, the reactions of oxides with salts can be conditionally attributed to the interaction of sulfuric and carbon dioxide with aqueous solutions or weigls of the corresponding salts - sulfite and carbonates, leading to the formation of acidic salts:

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

Caco 3 + CO 2 + H 2 O \u003d CA (HCO 3) 2

Also sulfur gas when passing it through aqueous solutions or carbonate suspension displaces carbon dioxide due to the fact that sulfuric acid is stronger and stable acid than coal:

K 2 CO 3 + SO 2 \u003d K 2 SO 3 + CO 2

OSR with oxide

Restoration of metal oxides and non-metals

Similarly, the metals can react with solutions of less active metals salts, displacing the latter in free form, oxides of metals during heating are also capable of reacting with more active metals.

Recall that it is possible to compare the activity of metals or using a number of metal activity, or if one or at once there are no two metals in a row of activity, according to their position relative to each other in the Mendeleev table: the lower the left metal, the more active. It is also useful to remember that any metal from the Schm family and Schism will always be more active than the metal that is not a representative of LEH or SHR.

In particular, on the interaction of metal with a less active metal oxide, the method of altertermia used in the industry to obtain such difficult-established metals as chromium and vanadium are founded:

CR 2 O 3 + 2AL \u003d t O.\u003d\u003e Al 2 O 3 + 2CR

When the process of the altertermia proceeds, a colossal amount of heat is formed, and the temperature of the reaction mixture can reach more than 2000 o C.

Also oxides of almost all metals, which are in series of activity, the right of aluminum can be reduced to free metals with hydrogen (H 2), carbon (C) and carbon monoxide (CO) during heating. For example:

Fe 2 O 3 + 3Co \u003d t O.\u003d\u003e 2fe + 3CO 2

Cuo + C \u003d t O.\u003d\u003e Cu + Co

Feo + H 2 \u003d t O.\u003d\u003e Fe + H 2 O

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

Fe 2 O 3 + Co \u003d T O.\u003d\u003e 2Feo + CO 2

4Cuo + C \u003d t O.\u003d\u003e 2CU 2 O + CO 2

Oxides of active metals (alkaline, alkaline earth, magnesium and aluminum) with hydrogen and carbon monoxide gas do not react.

However, active metal oxides react with carbon, but otherwise than oxides less active metals.

Within the framework of the USE program, in order not to be confused, it should be assumed that as a result of the reaction of the oxides of active metals (to AL inclusive) with carbon formation of free seam, schism, Mg, and Al can not. In such cases, the formation of metal and carbon monoxide carbide occurs. For example:

2AL 2 O 3 + 9C \u003d t O.\u003d\u003e Al 4 C 3 + 6Co

Cao + 3C \u003d t O.\u003d\u003e CAC 2 + CO

Nemetal oxides can often be restored to metals to free non-metals. For example, carbon and silicon oxides are reacting with alkaline, alkaline earth metals and magnesium:

CO 2 + 2MG \u003d t O.\u003d\u003e 2mgo + C

SiO 2 + 2mg \u003d t O.\u003d\u003e Si + 2mgo

With an excess of magnesium, the last interaction can also lead to education magnesium SilicideMG 2 Si:

SiO 2 + 4mg \u003d t O.\u003d\u003e MG 2 SI + 2MGO

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

Zn + 2NO \u003d t O.\u003d\u003e Zno + N 2

NO 2 + 2CU \u003d t O.\u003d\u003e 2Cuo + N 2

Oxynder oxide interaction

In order to be able to answer the question in the tasks of the Real EGE to answer the question, whether any oxygen with oxygen (O 2) responds, first of all, it is necessary to remember that oxides capable of reacting with oxygen (from those that can get caught in the exam itself) Former only chemical elements from the list:

carbon C, silicon Si, phosphor P, sulfur s, copper Cu, manganese Mn, iron FE, chrome CR, nitrogen N

Oxydes of any other chemical elements with oxygen react in real exams will not (!).

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

All chemical elements capable of forming oxides reacting with oxygen (from the exam)

First of all, among the listed elements should be considered nitrogen N, because The ratio of its oxides to oxygen is noticeably different from the oxides of the remaining elements of the list above.

It should be clearly remembered by the fact that five oxides are able to form all nitrogen, namely:

Of all nitrogen oxides with oxygen can react onlyNo. This reaction proceeds very easily when mixing NO both with pure oxygen and air. At the same time, there is a quick change in the color of the gas with colorless (NO) on the storm (NO 2):

2no.	+	O 2.	=	2NO 2.
colorless				brown

In order to answer the question - does any oxyge of any other of the above chemical elements (i.e., reacts with oxygen. FROM,SI, P., S., Cu., MN., FE., CR) — first of all, you must remember them maintenance The degree of oxidation (CO). Here they are :

Next, you need to remember the fact that from possible oxides of the above-mentioned chemical elements, with oxygen will be reacting only those that contain an element in the minimum, among the above, oxidation degree. At the same time, the degree of oxidation of the element rises to the nearest positive value from possible:

element	The attitude of its oxidesto oxygen
FROM	The minimum among the main positive degrees of carbon oxidation is equal to +2 , and the closest positive to it - +4 . Thus, with oxygen from oxides C +2 O and C +4 O 2, only CO responds. At the same time proceeds: 2C +2 O + O 2 \u003d t O.\u003d\u003e 2c +4 O 2 CO 2 + O 2 ≠ - the reaction is not possible in principle, because +4 - the highest degree of carbon oxidation.
SI	The minimum among the main positive degrees of silicon oxidation is +2, and the closest is positive - +4. Thus, with oxygen from oxides Si +2 O and Si +4 O 2, only SiO responds. Because of some singularities of SiO and SiO 2 oxides, only a part of silicon atoms in Si +2 oxide can be oxidized. As a result of its interaction with oxygen, mixed oxide is formed, containing both silicon to the degree of oxidation +2 and silicon to the degree of oxidation +4, namely Si 2 O 3 (Si +2 O · Si +4 O 2): 4Si +2 O + O 2 \u003d t O.\u003d\u003e 2SI +2, + 4 2 O 3 (Si +2 O · Si +4 O 2) SiO 2 + O 2 ≠ - the reaction is not possible in principle, because +4 - the highest degree of silicon oxidation.
P.	The minimum among the basic positive degrees of phosphorus oxidation is +3, and the closest to it is positive - +5. Thus, with oxygen from oxides P +3 2 O 3 and P +5 2 O 5, only P 2 O 3 reacts. At the same time, the reaction of phosphorus oxygen appearance is proceeding from oxidation degree of +3 to the degree of oxidation +5: P +3 2 O 3 + O 2 \u003d t O.\u003d\u003e P +5 2 O 5 P +5 2 O 5 + O 2 ≠ - the reaction is not possible in principle, because +5 - the highest degree of oxidation of phosphorus.
S.	The minimum among the main positive degrees of sulfur oxidation is +4, and the closest to it is positive - +6. Thus, with oxygen from oxides S +4 O 2, S +6 O 3 reacts only SO 2. At the same time proceeds: 2S +4 O 2 + O 2 \u003d t O.\u003d\u003e 2s +6 o 3 2S +6 O 3 + O 2 ≠ - the reaction is not possible in principle, because +6 - the highest degree of sulfur oxidation.
Cu.	The minimum among the positive degrees of copper oxidation is +1, and the closest to it is positive (and the only one) +2. Thus, with oxygen from Cu +1 2 O, Cu +2 O oxides, only Cu 2 O reacts. At the same time, the reaction proceeds: 2CU +1 2 O + O 2 \u003d t O.\u003d\u003e 4CU +2 O Cuo + O 2 ≠ - the reaction is not possible in principle, because +2 - the highest degree of copper oxidation.
CR	The minimum among the main positive degrees of oxidation of chromium is +2, and the closest value to it is +3. Thus, with oxygen from CR +2 O, CR +3 2 O 3 and CR +6 O 3 oxides, only CRO reacts, while oxidizing oxygen to the neighboring (from the possible) positive degree of oxidation, i.e. +3: 4Cr +2 O + O 2 \u003d t O.\u003d\u003e 2Cr +3 2 O 3 CR +3 2 O 3 + O 2 ≠ - The reaction does not proceed, despite the fact that there is chromium oxide and more than +3, oxidation degrees (CR +6 O 3). The impossibility of the flow of this reaction is associated with the fact that the heating required for its hypothetical implementation greatly exceeds the decomposition temperature of CRO 3. CR +6 O 3 + O 2 ≠ - This reaction cannot proceed in principle, because +6 - the highest degree of chromium oxidation.
MN.	The minimum among the main positive degrees of the oxidation of manganese is +2, and the closest to it is positive - +4. Thus, with oxygen from possible oxides Mn +2 O, Mn +4 O 2, Mn +6 O 3 and Mn +7 2 O 7, only MNO reacts, while oxidizing oxygen to the neighboring (from the possible) positive degree of oxidation, T .. +4: 2mn +2 O + O 2 \u003d t O.\u003d\u003e 2mn +4 O 2 while: Mn +4 O 2 + O 2and Mn +6 O 3 + O 2 ≠ - Reactions do not proceed, despite the fact that there is a manganese oxide Mn 2 O 7, containing Mn in a greater than +4 and +6, oxidation degrees. This is due to the fact that the MN oxides required for further hypothetical oxidation +4 O 2 and Mn +6 O 3 Heating significantly exceeds the decomposition temperature of the resulting oxides MnO 3 and Mn 2 O 7. Mn +7 2 O 7 + O 2 ≠ - This reaction is not possible in principle, because +7 - the highest degree of oxidation of manganese.
FE.	The minimum among the main positive degrees of iron oxidation is equal to +2 , and the closest to it among the possible - +3 . Despite the fact that for the iron there is a degree of oxidation of +6, the acid oxide FEO 3, however, as the corresponding "iron" acid does not exist. Thus, only those oxides that contain FE can be reacting from oxygen iron oxygen oxides. This is either FE oxide +2 O, or mixed iron oxide Fe +2 ,+3 3 O 4 (Iron Okalina): 4fe +2 O + O 2 \u003d t O.\u003d\u003e 2fe +3 2 O 3 or 6Fe +2 O + O 2 \u003d t O.\u003d\u003e 2fe + 2, + 3 3 O 4 mixed oxide Fe. +2,+3 3 O 4 can be milked before Fe +3 2 O 3: 4fe +2, + 3 3 O 4 + O 2 \u003d t O.\u003d\u003e 6fe +3 2 O 3 FE. +3 2 o 3 + o 2 ≠ - the flow of this reaction is not possible in principle, because Oxides containing iron into the degree of oxidation is higher than +3, does not exist.

Main oxides - These are oxides, which as hydroxide corresponds to the base.

Main oxides form only metals And, as a rule, in the degree of oxidation +1 and +2 (exception: BEO, ZNO, SNO, PBO).

sodium hydroxide-

basic hydroxide

(base)

Cao ⇒ CA (OH) 2

calcium hydroxide

basic hydroxide

(base)

Main oxides interact:

1. with acids, forming salt and water:

Basic oxide + acid \u003d salt + water

For example:

MGO + 2HCl \u003d MgCl 2 + H 2 O.

In the ion-molecular equations of the formula of oxides are recorded in a molecular form:

MGO + 2H + + 2 Cl - \u003d Mg 2+ + 2 C L - + H 2 O

MGO + 2H + \u003d Mg 2+ + H 2 O

2. With acid oxides, forming salts:

Basic oxide + acid oxide \u003d salt

For example:

Cao + N 2 O 5 \u003d Ca (NO 3) 2

In such equations, it is difficult to compile a reaction product formula. To find out which acid corresponds to this oxide, it is necessary to mentally add water to acid oxide and then derive the formula of the desired acid:

N 2 O 5 + ( H 2 O. ) → H 2 N 2 O 6

If all indexes are even in the resulting formula, then they should be reduced by 2. In our case, it turns out: hno 3. Salt of this acid is a reaction product. So:

2+ 2+ 2+ 2+ 2+
Cao + N 2 O 5 \u003d CaO + N 2 O 5 + (H 2 O) \u003d Cao + H 2 N 2 O 6 \u003d Cao + HNO 3 \u003d Ca (NO 3) 2 -

3. With water. But only oxides formed by alkaline react with water (Li 2.O,Na 2.O,K 2.O, etc.) and alkaline earth metals (Cao,SroBao), since the products of these reactions are soluble bases (alkali).

For example:

Cao + H 2 O \u003d Ca (OH) 2.

In order to derive from the formula of the oxide to derive the formula of the corresponding base, water can be written in the form: H + - OH - and show how one hydrogen ion H + from the water molecule is connected to the oxygen ion from CaO oxide and forms oh hydroxide ion. So:

Cao + H 2 O \u003d Cao + H + - OH - \u003d Ca (OH) 2.

The role of chemistry in scientific and technological progress is great. Many of the simple and complex substances are used in different areas of construction, industrial and agricultural spheres. Among them enough inorganic connections. The most important classes of inorganic compounds include oxides, bases, acids, salts.

Oxides.

Oxide - a complex substance that includes two elements, one of which oxygen into the degree of oxidation - 2. The total formula of oxides e x o, where X is the number of element atoms; U is the number of oxygen atoms.

Composition of oxides

The composition of the oxide is determined by the positive degree of oxidation of the element forming the oxide.

The name of the oxide is consisted of the word "oxide" and the name of the element. If the element exhibits a variable valence, a valence in brackets is set next to the name of the oxide:

Na 2 O - sodium oxide;

SO 3 - sulfur oxide (VI);

Obtaining oxides

Obtaining oxides:

a) oxidation of elements of oxygen

4Al + 3O 2 \u003d 2AL 2 O 3;

S + O 2 \u003d SO 2;

b) when decomposing complex substances

Ca (OH) 2 → CaO + H 2 O;

H 2 SO 3 → SO 2 + H 2 O;

c) when oxidizing complex substances

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

Classification of oxides

By chemical properties Oxides are divided by sale-forming and non-forming or indifferent (CO, NO, N 2 O, SIO).

The products of the interaction of oxides with water are called hydroxides, which can be bases (NaOH, Cu (OH) 2), acids (H 2 SO 4, H 3 PO 4), amphoteric hydroxides (ZnO (OH) 2 \u003d H 2 ZnO 2).

Salt-forming oxides are divided into maintenance, acidic and amphoteric.

Basic They call oxides to which the base corresponds: Cao → Ca (OH) 2, acidic- which corresponds to acid: CO 2 → H 2 CO 3. Amphoteric Oxides correspond to both acids and bases:

Zn (OH) 2 ← Zno → H 2 ZnO 2.

Maintenance oxides form metals, acidic - non-metals and some metals of side subgroups, amphoteric - amphoteric metals.

Chemical properties of oxides

Main oxides react:

1) With water to form grounds:

Na 2 O + H 2 O \u003d 2NAOH;

Cao + H 2 O \u003d Ca (OH) 2;

2) with acidic compounds (acid oxides, acids) to form salts and water:

Cao + CO 2 \u003d CASSO 3;

Cao + 2HCl \u003d CaCl 2 + H 2 O;

3) with amphoteric compounds:

Li 2 O + Al 2 O 3 \u003d 2LI ALO 2;

3NAOH + Al (ON) 3 \u003d Na 3 ALO 3 + 3N 2 O;

Acid oxides react:

1) with water to form acids:

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

2) with basic compounds (main oxides and bases) with the formation of salts and water:

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

CO 2 + 2NAOH \u003d Na 2 CO 3 + H 2 O;

3) with amphoteric compounds

CO 2 + ZnO \u003d Znco 3;

CO 2 + Zn (OH) 2 \u003d ZNSO 3 + H 2 O;

Amphoteric oxides exhibit properties of both basic and acidic oxides. Amphoteric hydroxides are answered:

Syclat medium alkaline environment
Ve (it) 2 veto n 2 veo 2

Zn (OH) 2 ZnO H 2 ZNO 2

AL (ON) 3 Al 2 O 3 H 3 ALo 3, NO 2

CR (ON) 3 CR 2 O 3 HCRO 2

PB (OH) 2 PBO H 2 PBO 2

SN (OH) 2 SNO H 2 SNO 2

Amphoteric oxides interact with escalating acid and primary nature:

Zno + sio 2 \u003d znsio 3; Zno + H 2 SiO 3 \u003d ZNSIO 3 + H 2 O;

Al 2 O 3 + 3NA 2 O \u003d 2NA 3 ALO 3; Al 2 O 3 + 2NAOH \u003d 2NAALO 2 + H 2 O.

Metals with variable valence can form oxides of all three types. For example:

Cro main CR (OH) 2;

CR 2 O 3 amphoterous CR (OH) 3;

CR 2 O 7 acid H 2 Cr 2 O 7;

MnO, Mn 2 O 3 main;

MNO 2 amphoterous;

Mn 2 O 7 Acid Hmno 4.

Oxides are complex substances consisting of two chemical elements, one of which is oxygen with oxidation degree ($ -2 $).

The general formula of oxides: $ e_ (M) O_n $, where $ M $ is the number of atoms of the element $ e $, and $ n $ is the number of oxygen atoms. Oxides can be solid ($ SiO_2 sand, quartz varieties), liquid (hydrogen oxide $ H_2O $), gaseous (Carbon oxides: carbon dioxide $ CO_2 $ and cut $ co $ gases). By chemical properties of oxides are divided into salt-forming and non-forming.

Non-forming These oxides are called, which do not interact with alkalis, nor with acids and do not form salts. There are few of them, their composition includes non-metals.

Salting-forming These oxides are called, which interact with acids or bases and form salt and water.

Among salt-forming oxides distinguish oxides main, acid, amphoteric.

Main oxides - These are such oxides, which correspond to the base. For example: $ Cao $ corresponds to $ Ca (OH) _2, Na_2O - NaOH $.

Typical reactions of main oxides:

1. Basic oxide + acid → Salt + water (exchange reaction):

$ Cao + 2hnO_3 \u003d Ca (NO_3) _2 + H_2O $.

2. Basic oxide + acid oxide → Salt (connection reaction):

$ MGO + SiO_2 (→) ↖ (T) MgSio_3 $.

3. Basic oxide + water → alkali (connection reaction):

$ K_2o + h_2o \u003d 2koh $.

Acid oxides - These are such oxides that correspond to acids. These are non-metallic oxides:

N2O5 corresponds to $ HNO_3, SO_3 - H_2SO_4, CO_2 - H_2CO_3, P_2O_5 - H_3PO_4 $, as well as metal oxides with a large value of oxidation degrees: $ (CR) ↖ (+6) O_3 $ corresponds to $ H_2CRO_4, (Mn_2) ↖ (+7 ) O_7 - HMNO_4 $.

Typical acid oxide reactions:

1. Acid oxide + base → Salt + water (exchange reaction):

$ SO_2 + 2NAOH \u003d Na_2SO_3 + H_2O $.

2. Acid oxide + main oxide → Salt (connection reaction):

$ Cao + Co_2 \u003d Caco_3 $.

3. Acid oxide + water → acid (connection reaction):

$ N_2o_5 + h_2o \u003d 2hno_3 $.

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

Amphoteric Oxides are called, which, depending on the conditions, show major or acidic properties. This is $ zno, al_2o_3, cr_2o_3, v_2o_5 $. Amphoteric oxides with water are not directly connected.

Typical reactions of amphoteric oxides:

1. Amphoteric oxide + acid → Salt + water (exchange reaction):

$ Zno + 2hcl \u003d znCl_2 + H_2O $.

2. Amphoteric oxide + base → Salt + water or comprehensive compound:

$ AL_2O_3 + 2NAOH + 3H_2O (\u003d 2NA,) ↙ (\\ Text "Tetrahydroxaluluminate sodium") $

$ AL_2O_3 + 2NAOH \u003d (2NAALO_2) ↙ (\\ Text "Sodium aluminate") + H_2O $.