Acidic oxide substance formula. What are oxides

All chemical compounds existing in nature are divided into organic and inorganic. Among the latter, the following classes are distinguished: oxides, hydroxides, salts. Hydroxides are divided into bases, acids and amphoteric. Among the oxides one can also distinguish acidic, basic and amphoteric. Substances last group can exhibit both acidic and basic properties.

Chemical properties of acid oxides

Such substances have peculiar Chemical properties. Acidic oxides are capable of entering into chemical reactions only with basic hydroxides and oxides. This group of chemical compounds includes substances such as carbon dioxide, sulfur dioxide and trioxide, chromium trioxide, manganese heptoxide, phosphorus pentoxide, chlorine trioxide and pentoxide, nitrogen tetra- and pentoxide, and silicon dioxide.

Such substances are also called anhydrides. The acidic properties of oxides appear primarily during their reactions with water. In this case, a certain oxygen-containing acid is formed. For example, if you take sulfur trioxide and water in equal quantities, you get sulfate (sulfuric) acid. Phosphoric acid can be synthesized in the same way by adding water to phosphorus oxide. Reaction equation: P2O5 + 3H2O = 2H3PO4. In exactly the same way, it is possible to obtain acids such as nitrate, silicic, etc. Also, acidic oxides enter into chemical interaction with basic or amphoteric hydroxides. During this type of reaction, salt and water are formed. For example, if you take sulfur trioxide and add calcium hydroxide to it, you get calcium sulfate and water. If we add zinc hydroxide, we get zinc sulfate and water. Another group of substances with which these chemical compounds interact are basic and amphoteric oxides. When reacting with them, only salt is formed, without water. For example, adding amphoteric aluminum oxide to sulfur trioxide produces aluminum sulfate. And if you mix silicon oxide with basic calcium oxide, you get calcium silicate. In addition, acidic oxides react with basic and normal salts. When reacting with the latter, acidic salts are formed. For example, if you add calcium carbonate and water to carbon dioxide, you can get calcium bicarbonate. Reaction equation: CO 2 + CaCO 3 + H 2 O = Ca (HCO 3) 2. When acidic oxides react with basic salts, normal salts are formed.

Substances of this group do not interact with acids or other acidic oxides. Amphoteric oxides can exhibit exactly the same chemical properties, only in addition they also interact with acidic oxides and hydroxides, that is, they combine both acidic and basic properties.

Physical properties and applications of acid oxides

There are quite a lot of different physical properties acid oxides, so they can be used in a wide variety of industries.

Sulfur trioxide

Most often this compound is used in the chemical industry. It is an intermediate product formed during the production of sulfate acid. This process involves burning iron pyrite to produce sulfur dioxide, which is then subjected to a chemical reaction with oxygen to form trioxide. Next, sulfuric acid is synthesized from the trioxide by adding water to it. Under normal conditions, this substance is a colorless liquid with an unpleasant odor. At temperatures below sixteen degrees Celsius, sulfur trioxide solidifies, forming crystals.

Phosphorus pentoxide

Acidic oxides also include phosphorus pentoxide. It is a white snow-like substance. It is used as a water-removing agent due to the fact that it very actively interacts with water, forming phosphoric acid (it is also used in chemical industry to obtain it).

Carbon dioxide

It is the most common of the acid oxides in nature. The content of this gas in the Earth's atmosphere is about one percent. Under normal conditions, this substance is a gas that has neither color nor odor. Carbon dioxide is widely used in the food industry: for the production of carbonated drinks, as a leavening agent, and as a preservative (under the designation E290). Liquefied carbon dioxide is used to make fire extinguishers. This substance also plays a huge role in nature - for photosynthesis, which results in the formation of oxygen vital for animals. Plants need carbon dioxide. This substance is released during the combustion of all organic chemical compounds without exception.

Silica

Under normal conditions it appears as colorless crystals. In nature, it can be found in the form of many different minerals, such as quartz, crystal, chalcedony, jasper, topaz, amethyst, and morion. This acidic oxide is actively used in the production of ceramics, glass, abrasives, concrete products, and fiber-optic cables. This substance is also used in radio engineering. In the food industry it is used in the form of an additive coded under the name E551. Here it is used to maintain the original shape and consistency of the product. This food supplement can be found, for example, in instant coffee. In addition, silicon dioxide is used in the production of toothpastes.

Manganese heptaoxide

This substance is a brown-green mass. It is used mainly for the synthesis of manganese acid by adding water to the oxide.

Nitrogen pentoxide

It is a solid, colorless substance in the form of crystals. It is used in most cases in the chemical industry to produce nitric acid or other nitrogen oxides.

Chlorine trioxide and tetroxide

The first is a green-yellow gas, the second is a liquid of the same color. They are used mainly in the chemical industry to produce the corresponding chlorous acids.

Preparation of acid oxides

Substances of this group can be obtained due to the decomposition of acids under the influence of high temperatures. In this case, the desired substance and water are formed. Examples of reactions: H 2 CO 3 = H 2 O + CO 2; 2H 3 PO 4 = 3H 2 O + P 2 O 5. Manganese heptaoxide can be obtained by treating potassium permanganate with a concentrated solution of sulfate acid. As a result of this reaction, the desired substance, potassium sulfate and water, is formed. Carbon dioxide can be obtained due to the decomposition of carboxylic acid, the interaction of carbonates and bicarbonates with acids, reactions baking soda with citric acid.

Conclusion

To summarize everything written above, we can say that acid oxides are widely used in the chemical industry. Only a few of them are also used in food and other industries.

Acidic oxides are large group inorganic chemical compounds that have great importance and can be used to produce a wide variety of oxygen-containing acids. This group also includes two important substances: carbon dioxide and silicon dioxide, the first of which plays a huge role in nature, and the second is presented in the form of many minerals, often used in the manufacture of jewelry.

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.

OXIDE

ACID

BASE

SALT

E x O y

NnA

A – acidic residue

Me(OH)b

OH – hydroxyl group

Me n A b

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.

Formula	Name	Formula	Name
	carbon(II) monoxide	Fe2O3	iron(III) oxide
	nitric oxide (II)	CrO3	chromium(VI) oxide
Al2O3	aluminium oxide		zinc oxide
N2O5	nitric oxide (V)	Mn2O7	manganese(VII) oxide

Oxides classification

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

Metal oxides Fur x O y

Non-metal oxides neMe x O y

Basic

Acidic

Amphoteric

Acidic

Indifferent

I, II

Meh

V-VII

ZnO,BeO,Al 2 O 3,

Fe 2 O 3 , Cr 2 O 3

> II

neMe

I, II

neMe

CO, NO, N2O

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 before 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 valence 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)

Acidic oxides

Basic oxides

Amphoteric oxides

Soluble in water.

Exception – SiO 2

(not soluble in water)

Only oxides of alkali and alkaline earth metals dissolve in water

(these are metals

I "A" and II "A" groups,

exception Be, Mg)

They do not interact with water.

Insoluble 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

Write down the oxides and classify them.

Obtaining oxides

Simulator "Interaction of oxygen with simple substances"

1. Combustion of substances (Oxidation with oxygen)	a) simple substances Training apparatus	2Mg +O 2 =2MgO
1. Combustion of substances (Oxidation with oxygen)	b) complex substances	2H 2 S+3O 2 =2H 2 O+2SO 2
2. Decomposition of complex substances (use table of acids, see appendices)	a) salts SALTt= BASIC OXIDE+ACID OXIDE	CaCO 3 = CaO + CO 2
	b) Insoluble bases Me(OH)bt= Me x O y+ H 2 O	Cu(OH)2t=CuO+H2O
	c) oxygen-containing acids NnA=ACID OXIDE + H 2 O	H 2 SO 3 =H 2 O+SO 2

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

CHEMICAL PROPERTIES OF BASIC OXIDES

1. Basic oxide + Acid oxide = Salt (r. compounds)

CaO + SO 2 = CaSO 3

2. Basic oxide + Acid = Salt + H 2 O (exchange solution)

3 K 2 O + 2 H 3 PO 4 = 2 K 3 PO 4 + 3 H 2 O

3. Basic oxide + Water = Alkali (compound)

Na 2 O + H 2 O = 2 NaOH

CHEMICAL PROPERTIES OF ACID OXIDES

1. Acid oxide + Water = Acid (r. compounds)

C O 2 + H 2 O = H 2 CO 3, SiO 2 – does not react

2. Acid oxide + Base = Salt + H 2 O (exchange exchange rate)

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

3. Basic oxide + Acidic oxide = Salt (r. compounds)

CaO + SO 2 = CaSO 3

4. Less volatile ones displace more volatile ones from their salts

CaCO 3 + SiO 2 = CaSiO 3 + CO 2

CHEMICAL PROPERTIES OF AMPHOTERIC OXIDES

They interact with both acids and alkalis.

ZnO + 2 HCl = ZnCl 2 + H 2 O

ZnO + 2 NaOH + H 2 O = Na 2 [Zn (OH) 4] (in solution)

ZnO + 2 NaOH = Na 2 ZnO 2 + H 2 O (when fused)

Application of oxides

Some oxides are insoluble 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.

Due to the insolubility and strength of chromium (III) oxide, it is also used in printing inks (for example, for coloring banknotes). In general, oxides of many metals are used as pigments for a wide variety of paints, although this is far from their only application.

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

Oxides are called complex substances whose molecules include oxygen atoms in oxidation state - 2 and some other element.

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

They are either salt-forming or non-salt-forming.

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

CuO + 2HCl → CuCl 2 + H 2 O.

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

CuO + SO 3 → CuSO 4.

Non-salt-forming oxides These are oxides that do not form salts. Examples include CO, N 2 O, NO.

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

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

Chemical properties of basic oxides

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

Na 2 O + H 2 O → 2NaOH.

2. React with acid oxides, forming the corresponding salts

Na 2 O + SO 3 → Na 2 SO 4.

3. React with acids to form salt and water:

CuO + H 2 SO 4 → CuSO 4 + H 2 O.

4. React with amphoteric oxides:

Li 2 O + Al 2 O 3 → 2LiAlO 2.

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

Chemical properties of acid oxides

1. React with water to form an acid:

SO 3 + H 2 O → H 2 SO 4.

But not all acidic oxides react directly with water (SiO 2, etc.).

2. React with based oxides to form a salt:

CO 2 + CaO → CaCO 3

3. React with alkalis, forming salt and water:

CO 2 + Ba(OH) 2 → BaCO 3 + H 2 O.

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

Chemical properties of amphoteric oxides

1. React with acids to form salt and water:

ZnO + 2HCl → ZnCl 2 + H 2 O.

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

ZnO + 2NaOH → Na 2 ZnO 2 + H 2 O.

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

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

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

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

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TO acid oxides relate:

all non-metal oxides, except non-salt-forming ones (NO, SiO, CO, N 2 O);
metal oxides in which the metal valency is quite high (V or higher).

Examples of acidic oxides are P 2 O 5 , SiO 2 , B 2 O 3 , TeO 3 , I 2 O 5 , V 2 O 5 , CrO 3 , Mn 2 O 7 . I would like to point out once again that metal oxides can also be classified as acidic. A well-known school saying: “Metal oxides are basic, non-metal oxides are acidic!” - this, sorry, is complete nonsense.

TO basic oxides include metal oxides for which two conditions are simultaneously met:

the valence of the metal in the compound is not very high (at least does not exceed IV);
the substance is not an amphoteric oxide.

Typical examples of basic oxides are Na 2 O, CaO, BaO and other oxides of alkali and alkaline earth metals, FeO, CrO, CuO, Ag 2 O, NiO, etc.

So, let's summarize. Oxides non-metals can be:

acidic (and the vast majority are such);
non-salt-forming (the corresponding 4 formulas should simply be remembered).

Oxides metals can be:

basic (if the oxidation state of the metal is not very high);
acidic (if the oxidation state of the metal is +5 or higher);
amphoteric (you should remember several formulas, but understand that the list given in the first part is not exhaustive).

And now a little test to check how well you have understood the topic “Classification of oxides”. If the test result is below 3 points, I recommend that you carefully read the article again.

01. Arsenic (V) oxide is: a) main; b) acidic; c) amphoteric; d) non-salt-forming. 02. The main oxides include: a) Na 2 O and SiO; b) Li 2 O and Cr 2 O 3; c) MnO and Rb 2 O; d) SiO 2 and P 2 O 5. 03. Oxides TeO 3 and NO are respectively: a) acidic and non-salt-forming; b) basic and acidic; c) amphoteric and non-salt-forming; d) amphoteric and basic. 04. Check the group that ONLY lists acid oxides: a) Re 2 O 7, N 2 O 4, SeO 2; b) SiO 2, CO 2, SiO; c) CrO, Cr 2 O 3, CrO 3; d) N 2 O, NO, N 2 O 5. 05. Choose a false statement: a) the metal oxide can be acidic, basic or amphoteric; b) the vast majority of non-metal oxides are acidic; c) among the non-salt-forming oxides, there is not a single one containing metal; d) the oxidation state of a nonmetal in an amphoteric oxide varies from -2 to -4.