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Chemical properties of 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

Oxides are inorganic compounds consisting of two chemical elements, one of which is oxygen in the -2 oxidation state. the only the non-oxidizing element is fluorine, which combines with oxygen to form oxygen fluoride. This is because fluorine is a more electronegative element than oxygen.

This class of compounds is very common. Every day a person encounters a variety of oxides in everyday life. Water, sand, the carbon dioxide we exhale, car exhaust, rust are all examples of oxides.

Classification of oxides

All oxides, according to their ability to form salts, can be divided into two groups:

1. Salt-forming oxides (CO 2, N 2 O 5, Na 2 O, SO 3, etc.)
2. Non-salt-forming oxides (CO, N 2 O, SiO, NO, etc.)

In turn, salt-forming oxides are divided into 3 groups:

• Basic oxides- (Metal oxides - Na 2 O, CaO, CuO, etc.)
• Acid oxides- (Non-metal oxides, as well as metal oxides in the oxidation state V-VII - Mn 2 O 7, CO 2, N 2 O 5, SO 2, SO 3, etc.)
• (Metal oxides with oxidation state III-IV as well as ZnO, BeO, SnO, PbO)

This classification is based on the manifestation of certain chemical properties by oxides. So, basic oxides correspond to bases, and acidic oxides correspond to acids. Acid oxides react with basic oxides to form the corresponding salt, as if the base and acid corresponding to these oxides had reacted: Likewise, amphoteric oxides correspond to amphoteric bases, which can exhibit both acidic and basic properties: Chemical elements exhibiting different oxidation states can form various oxides. In order to somehow distinguish between the oxides of such elements, after the name of the oxides, valency is indicated in brackets.

CO 2 - carbon monoxide (IV)

N 2 O 3 - nitric oxide (III)

Physical properties of oxides

Oxides are very diverse in their physical properties. They can be both liquids (H 2 O), and gases (CO 2, SO 3) or solids (Al 2 O 3, Fe 2 O 3). At the same time, basic oxides are, as a rule, solid substances. Oxides also have the most diverse color - from colorless (H 2 O, CO) and white (ZnO, TiO 2) to green (Cr 2 O 3) and even black (CuO).

• Basic oxides

Some oxides react with water to form the corresponding hydroxides (bases): Basic oxides react with acidic oxides to form salts: They react similarly with acids, but with the release of water: Oxides of metals less active than aluminum can be reduced to metals:

• Acid oxides

Acid oxides react with water to form acids: Some oxides (for example, silicon oxide SiO2) do not react with water, so acids are produced in other ways.

Acid oxides react with basic oxides to form salts: In the same way, with the formation of salts, acid oxides react with bases: If a given oxide corresponds to a polybasic acid, then an acid salt can also form: Non-volatile acid oxides can replace volatile oxides in salts:

As mentioned earlier, amphoteric oxides, depending on the conditions, can exhibit both acidic and basic properties. So they act as basic oxides in reactions with acids or acid oxides, with the formation of salts: And in reactions with bases or basic oxides, they exhibit acidic properties:

Obtaining oxides

Oxides can be obtained in a variety of ways, we will give the main ones.

Most oxides can be obtained by direct interaction of oxygen with a chemical element: When firing or burning various binary compounds: Thermal decomposition of salts, acids and bases: Interaction of some metals with water:

Application of oxides

Oxides are extremely common throughout the globe and are used both in everyday life and in industry. The most important oxide, hydrogen oxide, water, made life possible on Earth. Sulfur oxide SO 3 is used to produce sulfuric acid, as well as for food processing - this increases the shelf life, for example, of fruits.

Iron oxides are used to produce paints, the production of electrodes, although most iron oxides are reduced to metallic iron in metallurgy.

Calcium oxide, also known as quicklime, is used in construction. Oxides of zinc and titanium are white and insoluble in water, therefore they have become a good material for the production of paints - white.

Silicon oxide SiO 2 is the main component of glass. Chromium oxide Cr 2 O 3 is used for the production of colored green glasses and ceramics, and due to its high strength properties, for polishing products (in the form of GOI paste).

Carbon monoxide CO 2 , which all living organisms emit during respiration, is used for fire extinguishing, and also, in the form of dry ice, for cooling something.

Oxides complex substances are called, the composition of the molecules of which includes oxygen atoms in the oxidation state - 2 and some other element.

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

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

Salt-forming oxides- These are oxides that form salts as a result of chemical reactions. These are oxides of metals and non-metals, which, when interacting with water, form the corresponding acids, and when interacting with bases, the corresponding acidic and normal salts. For example, copper oxide (CuO) is a salt-forming oxide, because, for example, when it reacts with hydrochloric acid (HCl), a salt is formed:

CuO + 2HCl → CuCl 2 + H 2 O.

As a result of chemical reactions, other salts can be obtained:

CuO + SO 3 → CuSO 4.

Non-salt-forming oxides called oxides that do not form salts. An example is CO, N 2 O, NO.

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

Basic oxides such metal oxides are called, which correspond to hydroxides belonging to the class of bases. Basic oxides include, for example, Na 2 O, K 2 O, MgO, CaO, etc.

Chemical properties of basic oxides

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

Na 2 O + H 2 O → 2NaOH.

2. Interact with acid oxides, forming the corresponding salts

Na 2 O + SO 3 → Na 2 SO 4.

3. React with acids to form salt and water:

CuO + H 2 SO 4 → CuSO 4 + H 2 O.

4. React with amphoteric oxides:

Li 2 O + Al 2 O 3 → 2LiAlO 2 .

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

Chemical properties of acid oxides

1. Interact with water, forming acid:

SO 3 + H 2 O → H 2 SO 4.

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

2. React with based oxides to form a salt:

CO 2 + CaO → CaCO 3

3. Interact with alkalis, forming salt and water:

CO 2 + Ba (OH) 2 → BaCO 3 + H 2 O.

Part amphoteric oxide includes an element that has amphoteric properties. Amphotericity is understood as the ability of compounds to exhibit acidic and basic properties depending on the conditions. For example, zinc oxide ZnO can be both a base and an acid (Zn(OH) 2 and H 2 ZnO 2). Amphotericity is expressed in the fact that, depending on the conditions, amphoteric oxides exhibit either basic or acidic properties.

Chemical properties of amphoteric oxides

1. Interact with acids to form salt and water:

ZnO + 2HCl → ZnCl 2 + H 2 O.

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

ZnO + 2NaOH → Na 2 ZnO 2 + H 2 O.

When zinc oxide interacts with an alkali solution (the same NaOH), another reaction occurs:

ZnO + 2 NaOH + H 2 O => Na 2.

Coordination number - a characteristic that determines the number of nearest particles: atoms or ions in a molecule or crystal. Each amphoteric metal has its own coordination number. For Be and Zn it is 4; For and Al is 4 or 6; For and Cr it is 6 or (very rarely) 4;

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

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

What are oxides?

Oxides, their classification and properties - this is what needs to be understood paramount. So what are oxides? Do you remember this from the school curriculum?

Oxides (or oxides) are binary compounds, which include 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 an oxide compound are water, rust, some dyes, sand, and even carbon dioxide.

Oxide formation

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 - that's what scientists need to know in order to understand how this or that oxide was formed. For example, they can be obtained by direct connection of an oxygen atom (or atoms) with a chemical element - this is the interaction of chemical elements. However, there is also an indirect formation of oxides, this is when oxides are formed by the decomposition of acids, salts or bases.

Classification of oxides

Oxides and their classification depend on how they were 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, as a result of a chemical reaction with water, form acids, but when interacting with bases, they form the corresponding acids and salts.

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

Amphoteric oxides

Oxides, their classification and properties are very important concepts in chemistry. Salt-forming compounds include amphoteric oxides.

Amphoteric oxides are oxides that can exhibit basic or acidic properties, depending on the conditions of chemical reactions (show 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.

Acid oxides

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

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

Basic oxides

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

Basic oxides interact with acids, in contrast to acid oxides, as well as with alkalis, water, and other oxides. As a result of these reactions, as a rule, salts are 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.

Nevertheless, all oxides are different from each other. The classification and properties of oxides are two related topics.

Non-salt-forming oxides and their chemical properties

Non-salt-forming oxides are a group of oxides that exhibit neither acidic, nor basic, nor amphoteric properties. As a result of chemical reactions with non-salt-forming oxides, no salts are formed. Previously, such oxides were called not 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 non-metals.

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

Nomenclature

Almost all oxides are usually called like this: 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 is read like this: aluminum 2 o 3. Some chemical elements, such as copper, can have several degrees of oxidation, respectively, 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 of oxides, which are distinguished by the number of oxygen atoms in the compound. A monoxide or monoxide is an oxide that contains only one oxygen atom. Dioxides are those oxides that contain two oxygen atoms, as indicated by the prefix "di". Trioxides are those oxides that already contain three oxygen atoms. Names such as monoxide, dioxide, and trioxide are already obsolete, but are often found in textbooks, books, and other manuals.

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

So, an oxide is a combination 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 should be known in detail not only by scientists, but also by ordinary people, because they can even be dangerous for life on this earth. Oxides are a very interesting and fairly easy topic. Oxide compounds are very common in everyday life.

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, you first need to understand whether the oxide of the metal or non-metal is in front of you, and then use the algorithm (you need to learn it!), Presented in the following table:

non-metal oxide	metal oxide
1) Non-metal oxidation state +1 or +2 Conclusion: non-salt-forming oxide Exception: Cl 2 O is not a non-salt-forming oxide	1) Metal oxidation state +1 or +2 Conclusion: metal oxide is basic Exception: BeO, ZnO and PbO are not basic oxides
2) The oxidation state is greater than or equal to +3 Conclusion: acidic oxide Exception: Cl 2 O is an acid oxide, despite the oxidation state of chlorine +1	2) Metal oxidation state +3 or +4 Conclusion: amphoteric oxide Exception: BeO, ZnO and PbO are amphoteric despite the +2 oxidation state of metals 3) Metal oxidation state +5, +6, +7 Conclusion: acidic oxide

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

• To active basic oxides Let us refer oxides of alkali and alkaline earth metals (all elements of groups IA and IIA, except for hydrogen H, beryllium Be and magnesium Mg). For example, Na 2 O, CaO, Rb 2 O, SrO, etc.
• To inactive basic oxides we will assign all the main oxides that were 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 those reactions that do not enter into low-active ones.
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.

What oxides react with water?

Of all oxides with water react only:
1) all active basic oxides (oxides of alkaline metals and alkaline earth metals);
2) all acidic oxides, except for silicon dioxide (SiO 2);

those. From the foregoing, it follows that with water exactly do not 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 of the test part of the exam.

Now let's see how, after all, certain oxides react with water, i.e. learn how to write the corresponding reaction equations.

Active basic oxides, reacting with water, form their corresponding hydroxides. Recall that the corresponding metal oxide is the 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, the corresponding hydroxides K + 1 OH and Ba + 2 (OH) 2 are formed:

K 2 O + H 2 O \u003d 2KOH– potassium hydroxide

BaO + H 2 O \u003d Ba (OH) 2– barium hydroxide

All hydroxides corresponding to active basic oxides (oxides of alkali metals and alkali earth metals) are alkalis. Alkalis are all water-soluble metal hydroxides, 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 acid oxides, they correspond not to basic, but to acidic hydroxides, more often called oxygenated acids. Recall that the corresponding acid 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 acidic oxide SO 3 with water, first of all we must recall 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. Hydrosulfide acid H 2 S, as you can easily see, 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, sulfur in the +6 oxidation state, as in oxide SO 3, contains only sulfuric acid H 2 SO 4. Therefore, it is she who will be formed in the reaction of SO 3 with water:

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

Similarly, 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, as in N 2 O 5 , equal to +5, and in nitrogenous - +3:

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

Interaction of oxides with each other

First of all, it is necessary to clearly understand the fact that among salt-forming oxides (acidic, basic, amphoteric), reactions between oxides of the same class almost never occur, 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 between oxides belonging to different types is almost always possible, i.e. almost always flow reactions between:

1) basic oxide and acid oxide;

2) amphoteric oxide and acid oxide;

3) amphoteric oxide and basic oxide.

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

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

As a result of 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 original Me x O y) and the acid residue of the acid corresponding to the acid oxide.

For 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 acid oxide (P 2 O 5). In the second - amphoteric oxide (Al 2 O 3) and acid 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 acid 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 acid residue PO 4 3-, since the oxide P +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, 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 acid residue SO 4 2-, since the oxide S +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

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 the acidic one. As a result of this interaction, a salt of a specific composition is formed, consisting of a metal cation that forms the initial basic oxide and an "acid residue" / anion, which includes the metal from the amphoteric oxide. The formula of such an "acid residue" / anion in general form 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 the 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 as an example the interaction equations

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 an "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 containing a metal cation from the basic oxide is formed, i.e. Ba 2+ (from BaO) and "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 proceeds:

Me x O y + acid oxide,

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

However, two "finicky" acidic oxides should be remembered - carbon dioxide (CO 2) and sulfur dioxide (SO 2). Their “fastidiousness” lies in the fact that, despite the 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 earth metal). So, for example, Na 2 O and BaO, being active basic oxides, can react with them:

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

SO 2 + BaO = BaSO 3

While CuO and Al 2 O 3 oxides, 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. This forms salts and water:

FeO + H 2 SO 4 \u003d FeSO 4 + H 2 O

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

When does acid oxide react with acid?

When solving the part of the exam with answer options, you should conditionally assume that acid oxides do not react with either acid oxides or acids, except for 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 an excess of HF, the reaction equation has the form:

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

and in case of lack of HF:

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

2) SO 2, being an acid oxide, easily reacts with hydrosulfide acid H 2 S according to the type co-proportionation:

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, which include concentrated sulfuric acid and nitric acid of any concentration. In this case, the oxidation state of phosphorus increases from +3 to +5:

P2O3	+	2H2SO4	+	H2O	=t o=>	2SO2	+	2H3PO4
		(conc.)

3 P2O3	+	4HNO 3	+	7 H2O	=t o=>	4NO	+	6 H3PO4
		(razb.)

2HNO 3	+	3SO2	+	2H2O	=t o=>	3H2SO4	+	2NO
(razb.)

Interaction of oxides with metal hydroxides

Acid oxides react with metal hydroxides, both basic and amphoteric. In this case, a salt is formed, consisting of a metal cation (from the initial metal hydroxide) and an acid residue of the acid corresponding to the acid oxide.

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

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

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

CO 2 + NaOH = 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

The "finicky" oxides CO 2 and SO 2, whose activity, as already mentioned, is not enough for their reaction with low-activity basic and amphoteric oxides, nevertheless, react with most of the metal hydroxides corresponding to them. More precisely, carbon dioxide and sulfur dioxide interact with insoluble hydroxides in the form of their suspension in water. In this case, only basic about obvious salts, called hydroxocarbonates and hydroxosulfites, and the formation of medium (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, with metal hydroxides in the +3 oxidation state, for example, such as Al (OH) 3, Cr (OH) 3, etc., carbon dioxide and sulfur dioxide do not react at all.

It should also be noted the special inertness of silicon dioxide (SiO 2), which is most often found in nature in the form of ordinary sand. This oxide is acidic, however, among metal hydroxides, it is able to react 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 carrying out the reaction in aqueous solutions, soluble complex salts are formed:

ZnO + 2NaOH + H 2 O \u003d Na 2- sodium tetrahydroxozincate

BeO + 2NaOH + H 2 O \u003d Na 2- sodium tetrahydroxoberyllate

Al 2 O 3 + 2NaOH + 3H 2 O \u003d 2Na- sodium tetrahydroxoaluminate

Cr 2 O 3 + 6NaOH + 3H 2 O \u003d 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 MeO 2 x - type, 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 \u003d t o=> 2NaAlO 2 + H 2 O

Cr 2 O 3 + 2NaOH \u003d t o=> 2NaCrO 2 + H 2 O

Fe 2 O 3 + 2NaOH \u003d 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 their 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 found on the exam.

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

Al 2 O 3 + Na 2 CO 3 \u003d t o=> 2NaAlO 2 + CO 2

SiO 2 + K 2 SO 3 \u003d t o=> K 2 SiO 3 + SO 2

Also, the 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 \u003d 2NaHCO 3

CaCO 3 + CO 2 + H 2 O \u003d 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 \u003d K 2 SO 3 + CO 2

OVR involving oxides

Recovery of oxides of metals and non-metals

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

Recall that you can compare the activity of metals either using the activity series of metals, or, if one or two metals are not in the activity series at once, by their position relative to each other in the periodic table: the lower and to the left of the metal, the more active it is. It is also useful to remember that any metal from the SM and SHM family will always be more active than a metal that is not a representative of SHM or SHM.

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

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

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

Also, oxides of almost all metals that are in the activity series to the right of aluminum can be reduced to free metals with 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 + H 2 \u003d t o=> Fe + H 2 O

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

Fe 2 O 3 + CO =to=> 2FeO + CO 2

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

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

However, oxides of active metals react with carbon, but in a different way than oxides of less active metals.

Within the framework of the USE program, in order not to be confused, it should be considered that as a result of the reaction of active metal oxides (up to Al inclusive) with carbon, the formation of free alkaline metals, alkaline earth metals, Mg, and also Al is impossible. In such cases, the formation of metal carbide and carbon monoxide occurs. For example:

2Al 2 O 3 + 9C \u003d t o=> Al 4 C 3 + 6CO

CaO + 3C = t o=> CaC2 + CO

Non-metal oxides can often be reduced by metals to free non-metals. So, for example, oxides of carbon and silicon, when heated, react with alkali, alkaline earth metals and magnesium:

CO 2 + 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 Mg2Si:

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

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 exam, you first need to remember that oxides that can react with oxygen (of those that you can come across on the exam itself) can form only chemical elements from the list:

Oxides of any other chemical elements encountered in the real USE react with oxygen will not (!).

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

All chemical elements capable of forming oxides that react with oxygen (from those encountered in 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 the rest of the elements in the above list.

It should be clearly remembered that in total nitrogen is capable of forming five oxides, namely:

Of all nitrogen oxides, oxygen can react only NO. This reaction proceeds 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:

2NO	+	O2	=	2NO 2
colorless				brown

In order to answer the question - does any oxide of any other of the above chemical elements react with oxygen (i.e. WITH,Si, P, S, Cu, Mn, Fe, Cr) — First of all, you need to remember them main 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, among the above, oxidation states will react with oxygen. In this case, the oxidation state of the element rises to the nearest positive value possible:

element	The ratio of its oxidesto oxygen
With	The minimum among the main positive oxidation states of carbon is +2 , and the closest positive to it is +4 . Thus, only CO reacts with oxygen from the oxides C +2 O and C +4 O 2. In this case, the reaction proceeds: 2C +2 O + O 2 = t o=> 2C+4O2 CO 2 + O 2 ≠- the reaction is impossible in principle, because +4 is the highest oxidation state of carbon.
Si	The minimum among the main positive oxidation states of silicon is +2, and the closest positive to it is +4. Thus, only SiO reacts with oxygen from the oxides Si +2 O and Si +4 O 2 . Due to some features of the oxides SiO and SiO 2, only a part of the silicon atoms in the oxide Si + 2 O can be oxidized. as a result of its interaction with oxygen, a mixed oxide is formed containing both silicon in the +2 oxidation state and silicon in the +4 oxidation state, namely Si 2 O 3 (Si +2 O Si +4 O 2): 4Si +2 O + O 2 \u003d t o=> 2Si +2, +4 2 O 3 (Si +2 O Si +4 O 2) SiO 2 + O 2 ≠- the reaction is impossible in principle, because +4 is the highest oxidation state of silicon.
P	The minimum among the main positive oxidation states of phosphorus is +3, and the closest positive to it is +5. Thus, only P 2 O 3 reacts with oxygen from oxides P +3 2 O 3 and P +5 2 O 5 . In this case, the reaction of additional oxidation of phosphorus with oxygen proceeds from the oxidation state +3 to the oxidation state +5: P +3 2 O 3 + O 2 = t o=> P +5 2 O 5 P +5 2 O 5 + O 2 ≠- the reaction is impossible in principle, because +5 is the highest oxidation state of phosphorus.
S	The minimum among the main positive oxidation states of sulfur is +4, and the closest positive to it in value is +6. Thus, only SO 2 reacts with oxygen from oxides S +4 O 2 , S +6 O 3 . In this case, the reaction proceeds: 2S +4 O 2 + O 2 \u003d t o=> 2S +6 O 3 2S +6 O 3 + O 2 ≠- the reaction is impossible in principle, because +6 is the highest oxidation state of sulfur.
Cu	The minimum among the positive oxidation states of copper is +1, and the closest to it in value is the positive (and only) +2. Thus, only Cu 2 O reacts with oxygen from oxides Cu +1 2 O, Cu +2 O. In this case, the reaction proceeds: 2Cu +1 2 O + O 2 = t o=> 4Cu+2O CuO + O 2 ≠- the reaction is impossible in principle, because +2 is the highest oxidation state of copper.
Cr	The minimum among the main positive oxidation states of chromium is +2, and the closest positive to it in value is +3. Thus, only CrO reacts with oxygen from oxides Cr +2 O, Cr +3 2 O 3 and Cr +6 O 3, while being oxidized by oxygen to the next (out of possible) positive oxidation state, i.e. +3: 4Cr +2 O + O 2 \u003d t o=> 2Cr +3 2 O 3 Cr +3 2 O 3 + O 2 ≠- the reaction does not proceed, despite the fact that chromium oxide exists and in an oxidation state greater than +3 (Cr +6 O 3). The impossibility of this reaction occurring is due to the fact that the heating required for its hypothetical implementation greatly exceeds the decomposition temperature of CrO 3 oxide. Cr +6 O 3 + O 2 ≠ - this reaction cannot proceed in principle, because +6 is the highest oxidation state of chromium.
Mn	The minimum among the main positive oxidation states of manganese is +2, and the closest positive to it is +4. Thus, of the possible oxides Mn +2 O, Mn +4 O 2, Mn +6 O 3 and Mn +7 2 O 7, only MnO reacts with oxygen, while being oxidized by oxygen to the neighboring (out of possible) positive oxidation state, t .e. +4: 2Mn +2 O + O 2 = t o=> 2Mn +4 O 2 while: Mn +4 O 2 + O 2 ≠ and Mn +6 O 3 + O 2 ≠- reactions do not proceed, despite the fact that there is manganese oxide Mn 2 O 7 containing Mn in a higher oxidation state than +4 and +6. This is due to the fact that the required for further hypothetical oxidation of Mn oxides +4 O2 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 impossible in principle, because +7 is the highest oxidation state of manganese.
Fe	The minimum among the main positive oxidation states of iron is +2 , and the closest to it among the possible - +3 . Despite the fact that for iron there is an oxidation state of +6, the acid oxide FeO 3, however, as well as the corresponding “iron” acid, does not exist. Thus, of the iron oxides, only those oxides that contain Fe in the +2 oxidation state can react with oxygen. It's either Fe oxide +2 O, or mixed iron oxide Fe +2 ,+3 3 O 4 (iron scale): 4Fe +2 O + O 2 \u003d t o=> 2Fe +3 2 O 3 or 6Fe +2 O + O 2 \u003d t o=> 2Fe +2,+3 3 O 4 mixed Fe oxide +2,+3 3 O 4 can be further oxidized to Fe +3 2O3: 4Fe +2 ,+3 3 O 4 + O 2 = t o=> 6Fe +3 2 O 3 Fe +3 2 O 3 + O 2 ≠ - the course of this reaction is impossible in principle, because oxides containing iron in an oxidation state higher than +3 do not exist.