Oxides are complex substances consisting of two elements, one of which is oxygen. In the names of oxides, the word oxide is first indicated, then the name of the second element by which it is formed. What are the features of acidic oxides, and how do they differ from other types of oxides?

Classification of oxides

Oxides are divided into salt-forming and non-salt-forming. Already from the name it is clear that non-salt-forming ones do not form salts. There are few such oxides: water H 2 O, oxygen fluoride OF 2 (if it is conventionally considered an oxide), carbon monoxide, or carbon monoxide (II), carbon monoxide CO; nitrogen oxides (I) and (II): N 2 O (dinitrogen oxide, laughing gas) and NO (nitrogen monoxide).

Salt-forming oxides form salts when interacting with acids or alkalis. Bases, amphoteric bases and oxygen-containing acids correspond to them as hydroxides. Accordingly, they are called basic oxides (eg CaO), amphoteric oxides (Al 2 O 3) and acid oxides or acid anhydrides (CO 2).

Rice. 1. Types of oxides.

Often, students are faced with the question of how to distinguish a basic oxide from an acidic one. First of all, you need to pay attention to the second element next to oxygen. Acid oxides - contain a non-metal or a transition metal (CO 2, SO 3, P 2 O 5); basic oxides - contain a metal (Na 2 O, FeO, CuO).

Basic properties of acid oxides

Acidic oxides (anhydrides) are substances that exhibit acidic properties and form oxygenated acids. Therefore, acidic oxides correspond to acids. For example, acidic oxides SO 2, SO 3 correspond to the acids H 2 SO 3 and H 2 SO 4.

Rice. 2. Acidic oxides with corresponding acids.

Acidic oxides formed by non-metals and metals with variable valence in the highest oxidation state (for example, SO 3, Mn 2 O 7) react with basic oxides and alkalis to form salts:

SO 3 (acidic oxide) + CaO (basic oxide) = CaSO 4 (salt);

Typical reactions are the interaction of acidic oxides with bases resulting in the formation of salt and water:

Mn 2 O 7 (acidic oxide) + 2KOH (alkali) = 2KMnO 4 (salt) + H 2 O (water)

All acidic oxides, except for silicon dioxide SiO 2 (silicic anhydride, silica), react with water, forming acids:

SO 3 (acidic oxide) + H 2 O (water) = H 2 SO 4 (acid)

Acid oxides are formed by interaction with oxygen of simple and complex substances (S + O 2 = SO 2), or by decomposition as a result of heating complex substances containing oxygen - acids, insoluble bases, salts (H 2 SiO 3 = SiO 2 + H 2 O).

List of acidic oxides:

Acid Oxide Name	Acid Oxide Formula	Acid Oxide Properties
Sulfur (IV) oxide	SO 2	colorless toxic gas with a pungent odor
Sulfur (VI) oxide	SO 3	highly volatile colorless toxic liquid
Carbon monoxide (IV)	CO 2	colorless, odorless gas
Silicon (IV) oxide	SiO 2	colorless crystals with strength
Phosphorus (V) oxide	P 2 O 5	white, highly flammable powder with an unpleasant odor
Nitric oxide (V)	N 2 O 5	substance composed of colorless volatile crystals
Chlorine (VII) oxide	Cl 2 O 7	colorless oily toxic liquid
Manganese (VII) oxide	Mn 2 O 7	liquid with a metallic luster, which is a strong oxidizing agent.

Rice. 3. Examples of acidic oxides.

What have we learned?

Acidic oxides are salt-forming oxides and are formed with acids. Acidic oxides react with bases and water, and their formation occurs when complex substances are heated and decomposed.

Test by topic

Assessment of the report

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Formula of oxides is necessary for the possibility of solving problems and understanding the possible variants of compounds of chemical elements. General formula of oxides- E x O y. Oxygen is in second place after fluorine in terms of value electronegativity, which is the reason that most of the compounds of chemical elements with oxygen are oxides.

By classification of oxides, salt-forming oxides are those oxides, which can interact with acids or bases with the possibility of the appearance of the corresponding salt and water. Salt-forming oxides are called:

Basic oxides, often formed from metals with oxidation states +1, +2. They can react with acids, with acidic oxides, with amphoteric oxides, with water (only oxides of alkali and alkaline earth metals). The basic oxide element becomes a cation in the resulting salt. Na 2 O, CaO, MgO, CuO.

1. Basic oxide + strong acid → salt + water: CuO + H 2 SO 4 → CuSO 4 + H 2 O
2. Strong base oxide + water → hydroxide: CaO + H 2 O → Ca (OH) 2
3. Strong base oxide + acidic oxide → salt: CaO + Mn 2 O 7 → Ca (MnO 4) 2
4. Basic oxide + hydrogen → metal + water: CuO + H 2 → Cu + H 2 O

Note: the metal is less active than aluminum.

Acidic oxides- oxides of non-metals and metals in the oxidation state +5 - +7. They can react with water, alkalis, basic oxides, amphoteric oxides. The acidic oxide element is part of the anion of the resulting salt. Mn 2 O 7, CrO 3, SO 3, N 2 O 5.

1. Acid oxide + water → acid: SO 3 + H 2 O → H 2 SO 4. Some oxides, for example SiO 2, cannot react with water, so their acids are obtained indirectly.
2. Acid oxide + basic oxide → salt: CO 2 + CaO → CaCO 3
3. Acid oxide + base → salt + water: SO 2 + 2NaOH → Na 2 SO 3 + H 2 O. If the acid oxide is an anhydride of a polybasic acid, acidic or medium salts may form: Ca (OH) 2 + CO 2 → CaCO 3 ↓ + H 2 O, CaCO 3 + H 2 O + CO 2 → Ca (HCO 3) 2
4. Non-volatile oxide + salt 1 → salt 2 + volatile oxide: SiO 2 + Na 2 CO 3 → Na 2 SiO 3 + CO 2
5. Acid anhydride 1 + anhydrous oxygen-containing acid 2 → Acid anhydride 2 + anhydrous oxygen-containing acid 1: 2P 2 O 5 + 4HClO 4 → 4HPO 3 + 2Cl 2 O 7

Amphoteric oxides, form metals with an oxidation state from +3 to +5 (BeO, ZnO, PbO, SnO also belong to amphoteric oxides). React with acids, alkalis, acidic and basic oxides.

When interacting with a strong acid or acidic oxide, they show basic properties: ZnO + 2HCl → ZnCl 2 + H 2 O

When interacting with a strong base or basic oxide, they show acidic properties:

• ZnO + 2KOH + H 2 O → K 2 (in aqueous solution).
• ZnO + 2KOH → K 2 ZnO 2 (fusion).

Non-salt-forming oxides do not react with either acids or bases, which means they do not form salts. N 2 O, NO, CO, SiO.

In accordance with the IUPAC nomenclature, the names of oxides are composed of the word oxide and the name of the second chemical element(with less electronegativity) in the genitive case:

• Calcium oxide - CaO.

If an element can form several oxides, then their names should indicate the oxidation state of the element:

• Fe 2 O 3 - iron (III) oxide;
• MnO 2 - manganese (IV) oxide.

You can use Latin prefixes to denote the number of atoms of elements that are included in the oxide molecule:

• Na 2 O - disodium oxide;
• CO is carbon monoxide;
• CO 2 - carbon dioxide.

The trivial names for some oxides are also often used:

Oxides names.

Oxide Formula	Systematic name	Trivial name
		Carbon monoxide
		Carbon dioxide
	Magnesium oxide	Magnesia
	Calcium oxide	Quicklime
	Iron (II) oxide	Iron oxide
Fe 2 O 3	Iron (III) oxide	Iron oxide
	Phosphorus (V) oxide	Phosphoric anhydride
H 2 O 2	Hydrogen peroxide
SO 2	Sulfur (IV) oxide
Ag 2 O	Silver (I) oxide
Cu 2 O 3	Copper (III) oxide	dimedi trioxide
CuO	Copper (II) oxide	copper oxide
Cu 2 O	Copper (I) oxide	Copper oxide, copper hemioxide, dimedium oxide

Draw up the oxide formula.

At formulating oxide the first is the element, the oxidation state of which is with the + sign, and the second is the element with the negative oxidation state. For oxides, this is always oxygen.

Subsequent steps to formulate the oxide:

1. Arrange the oxidation state (oxidation state) for each atom. Oxygen in oxides always has an oxidation state of -2 (minus two).

2. In order to know correctly oxidation state the second element, you need to look at the table of possible oxidation states of some elements.

When compiling the names of substances, I most often use the Russian names of elements, for example, dioxygen, xenon difluoride, potassium selenate. Sometimes, for some elements, the roots of their Latin names are introduced into the derivative terms:

The names of the elements in the formulation of oxides.

Ag - Argent
As - ars, arsen	Ni - nikkol
	O - ox, oxygen
C - carb, carbon
H - hydr, hydrogen	Si - sil, silic, silic
Hg - merkur
Mn - mangan

For example: carbonate, manganate, oxide, sulfide, silicate.

The names of simple substances consist of one word - the name of a chemical element with a numeric prefix, for example:

The following numeric prefixes are used:

Numeric prefixes in the formulation of oxides.

An indefinite number is indicated by a numeric prefix n- poly.

The names of common acidic hydroxides consist of two words: their own name with the ending "ah" and the group word "acid". Here are the formulas and proper names of common acidic hydroxides and their acidic residues (a dash means that hydroxide not known in free form or in acidic aqueous solution):

Formulas and proper names of common acidic hydroxides and their acidic residues.

Acidic hydroxide	Acidic residue
HAsO 2 - meta-arsenic	AsO 2 - - meta-arsenite
H 3 AsO 3 - ortho-arsenic	AsO 3 3- - orthoarsenite
H 3 AsO 4 - arsenic	AsO 4 3- - arsenate
	В 4 О 7 2- - tetraborate
	BiO 3 - - bismuthate
HBrO - hypobromous	BrO - - hypobromite
HBrO 3 - bromic	BrO 3 - - bromate
H 2 CO 3 - coal	CO 3 2- - carbonate
HClO - hypochlorous	ClO - - hypochlorite
HClO 2 - chloride	ClO 2 - - chlorite
HClO 3 - chloric	ClO 3 - - chlorate
HClO 4 - chloric	ClO 4 - - perchlorate
H 2 CrO 4 - chrome	CrO 4 2- - chromate
	HCrO 4 - - hydrochromate
H 2 Cr 2 O 7 - dichromic	Cr 2 O 7 2- - dichromate
	FeO 4 2- - ferrate
HIO 3 - iodic	IO 3 - - iodate
HIO 4 - metayode	IO 4 - - metaperiodate
H 5 IO 6 - orthoiodic	IO 6 5- - orthoperiodate
HMnO 4 - manganese	MnO 4 - - permanganate
	MnO 4 2- - manganate
	MoO 4 2- - molybdate
HNO 2 - nitrogenous	NO 2 - - nitrite
HNO 3 - nitrogen	NO 3 - - nitrate
HPO 3 - metaphosphoric	PO 3 - - metaphosphate
H 3 PO 4 - orthophosphoric	PO 4 3- - orthophosphate
	НPO 4 2- - hydrogen phosphate
	H 2 PO 4 - - dihydrogen phosphate
H 4 P 2 O 7 - diphosphoric	P 2 O 7 4- - diphosphate
	ReO 4 - - perrnat
	SO 3 2- - sulfite
	HSO 3 - - hydrosulfite
H 2 SO 4 - sulfuric	SO 4 2- - sulfate
	НSO 4 - - hydrogen sulfate
H 2 S 2 O 7 - disulfide	S 2 O 7 2- - disulfate
H 2 S 2 O 6 (O 2) - peroxodisulfur	S 2 O 6 (O 2) 2- - peroxodisulfate
H 2 SO 3 S - thiosulfur	SO 3 S 2- - thiosulfate
H 2 SeO 3 - selenium	SeO 3 2- - selenite
H 2 SeO 4 - selenium	SeO 4 2- - selenate
H 2 SiO 3 - metasilicon	SiO 3 2- - metasilicate
H 4 SiO 4 - orthosilicon	SiO 4 4- - orthosilicate
H 2 TeO 3 - tellurium	TeO 3 2- - tellurite
H 2 TeO 4 - metatelluric	TeO 4 2- - metatellurate
H 6 TeO 6 - Orthotelluric	TeO 6 6- - orthotellurate
	VO 3 - - metavanadat
	VO 4 3- - orthovanadat
	WO 4 3- - tungstate

Less common acidic hydroxides are named after the nomenclature rules for complex compounds, for example.

Control test on the topic "Compound of chemical elements", grade 8. Option 2

Part A.

1. (3 points). A pure substance, as opposed to a mixture, is:A. Sea water.B. Milk.V. Air.G. Oxygen.

2 (3 points). A series of formulas in which everything is— entities - grounds:

A. WITHu(HE) 2 , CuCI 2 , NaOH.B. Ca (OH) 2 , Mg (OH) 2 , MgOHCI.

V ... KOH, Va (OH) 2, WITHu(HE) 2 . G. NSl, NaOH,NaCl.

3 (3 points). Carbon exhibits the lowest ste— oxidation stump in conjunction with the formula:

A ... CH 4 . B. N 2 CO 3 . V ... CO 2 . G. CO.

4 (3 points). The general formula of the oxide is depicted by a conditional notation:

A. M (OH) x . V. M x (NS) at

B. NS NS O Have . G. N NS NS.

M - metal, E - element, KO - acid residue.

5 (3 points). The number of salt formulas is in the following list:H 2 CO 3 , Fe( OH) 3 , KNO 3 , NaOH, Ba( OH) 2 , CaO, SO 2 , CaCO 3 - equals:

A.1 B.2 C.3 D.4

6 (3 points). Mass fraction of aluminum in aluminum oxide Al 2 Oz is equal to:

A. 52.94%. B. 0.36% C. 26.47% D. 73.00%

7 (3 points). 20 g of NaCl was dissolved in 180 g of water. The mass fraction of sodium chloride in the resulting solution is equal to:

A. 11%. B. 15%. V. 20%. G. 10%

8 (3 points). Copper chloride formula (II):

A . CuClB . Si 2 SO 4 V . CuCl 2 . G. CuSO 4 .

9 (3 points). The acid formula in which the charge of the ion of the acid residue is 3 -:

A ... NSl. B. N 3 RO 4 . V. N 2 SO 4 . G. HNO 3 .

10 (3 points). A water-insoluble base is a substance with the formula:

A ... NaOH.B . KOH.V . Fe (OH) 3 . G. Ba( OH) 2 .

11 (6 points) Relate.

Compound Formula:

1. K 2 O. 2. CaSO 4 . 3. N 2 SO 4. 4. KOH 5. SO 2 6. HNO 3

Connection class:

A. Oxides. B. Grounds. B. Acids. G. Salt.

12. (4 points)Relate.

Compound Formula: 1.MnCL 2 2. Fe( OH) 2 3. Fe (OH) 3 4.H 2 SO 4 5. MgCl 2 6. MgO 7. MnOName of substance: A. Magnesium oxide. B. Sulfuric acid c. Iron (3) hydroxide d. Magnesium chloride

Part B Free answer tasks

13. (6 points) For a hydroxide (acid or base), write the formula of the corresponding oxide: A.H 2 SiO 3 B.Ca( OH) 2 V.Fe( OH) 3

14. (4 points)

Write the chemical formulas of the compounds: A. aluminum oxide (3) B. sodium nitrate C. potassium sulfate D. zinc hydroxide (2)

15. (6 points) Calculate the volume of nitrogen obtained from 200 liters of air if the volume fraction of nitrogen in the air is 78%.

Control test on the topic " Compound of chemical elements ",8th grade. Option 1

Part A. Test tasks with the choice of one correct answer and for correlation

1 (3 points). A mixture of substances, in contrast to an individual substance, is:A. Tap water.B ... Carbon dioxide.V. Oxygen.G. Copper

2 (3 points). A number of formulas in which all substances are oxides:A. ZnO, ZnCl 2 , H 2 O. B. CaO, NaOH, NH 3 V. SO 3 , MgO, CuO. G. KOH, K 2 O, MgO.

3 (3 points). Nitrogen exhibits the highest oxidation state when combined with the formula:A. NH 3 . B. NO 2 . V. N 2 O 5 . G. NO.

4 (3 points). The general formula of the base is expressed— on a conditional record:

A. M( OH) x . B. NS NS O at . V ... NS NS N at . G. N NS KO M - metal, E - element, KO - acid residue.

5 (3 points). The number of acid formulas in the following list: H 2 CO 3 , Fe (OH) 2 , NaOH, H 2 SiO 3 , Wa (OH) 2 ,
Cu (OH) 2 , CaO, SO 2 - equals:A. 1 ... B. 2 ... V. 3. G. 4.

6 (3 points). Mass fraction of sulfur in sulfuric acid Н 2 SO 4 is equal to:A . 2,04%. B. 65,31%. V. 52,34%. G . 32,65% .

7 (3 points). In 80 g of water, 20 g of salt was dissolved. The mass fraction of salt in the resulting solution is equal to:
A . 20% . B. 25% . V. 40% . G. 30% .

8 (3 points). Ferrous Sulfate Formula (II): A. FeS. B . FeSO 3 . V . Fe 2 (SO 4 ) 3 . G. FeSO 4

9 (3 points). The acid formula, in which the charge of the ion of the acid residue is 2 -:
A. NSl. B. H 2 SO 4 . V . H 3 PO 4 ... G. HNO 3 .

10 (3 points). Alkali is a substance with— mule:

A. Al(OH) h.B . Fe (OH) 2 , . V . KOH. G. Cu(OH) 2 .

11 (3 points). Relate.

Formulaconnections:

1. Na 2 O. 2 .MgSO 4 . 3 .NaOH.4 . HCl.5. CO 2 . 6 ... N 3 RO 4 .

Connection class: A. Oxides.B. Foundations.V. Acids.G. Salt.

12 (3 points). Relate.

Compound Formula:

1 ... HNO 3 . 2. Al 2 O 3 . 3. Ca (OH) 2 . 4. CaSO 4 . 5. CaO. 6. H 3 PO 4 . 7. Al(OH) h.8. TO 2 SO 4 .
Substance name:

A. Calcium oxide.B. Nitric acid.V. Aluminum hydroxide.G. Potassium sulfate.

Part B ... Free answer tasks

13 (6 points). For hydroxides (acid or base), write the formulas of the corresponding oxides:A. H 2 CO 3 . B. Mg(OH) 2 ... V. Al(OH) 3 .

14 (4 points). Make up the chemical formulas of the compounds:A. Potassium oxide.B ... Hydrochloric acid.V. Calcium phosphate.G. Barium hydroxide.

15 (6 points). Calculate the volume of oxygen obtained from 200 liters of air if the volume fraction of oxygen in the air is known to be 21%.

The key of the answers to the test.

Part A

Option 1
question	1	2	3	4	5	6	7	8	9	10	11	12
answer	G	V	G	B	B	A	G	V	B	V	A-1.5 B-4 C-3.6 G-2	A-6 B-4 C-3 D-5
Part A	Option 2
question	1	2	3	4	5	6	7	8	9	10	11	12
answer	A	V	V	A	B	G	A	G	B	V	A-1.5 B-3 C-4.6 G-2	А-5 B-1 В-7 Г-8

52-49 points score "5"

48-38 points score "4"

37-28 points score "3"

27 - 12 points score "2"

Part A. Test tasks with the choice of one correct answer and for correlation

1. A mixture of substances is not:

2. A number of formulas, in which all substances are acids:

3. Sulfur exhibits the highest oxidation state in the compound, the formula of which is:

4. The general formula of salts is depicted by a conventional notation:

5. The number of oxide formulas in the following list: NaOH, K2O, MgCl2, SO2, BaSO4, OF2, Ca (OH) 2, H2O is equal to:

6. Mass fraction of nitrogen in nitric acid HNO3 is equal to:

7. In 20 g of water was dissolved 30 g of salt. The mass fraction of salt in the resulting solution is equal to:

8. Formula of chromium (III) sulfate:

9. An acid in which the charge of the ion of the acid residue is 2- has the formula:

10. A base insoluble in water is a substance with the formula:

11. Correlate:
Compound formula: 1. H2SO3 2. SO3 3. BaCl2 4. Ca (OH) 2 5. ZnO 6. Al (OH) 3
Class of compounds: A. Oxides B. Bases C. Acids D. Salts

12. Correlate:
Compound formula: 1. KOH 2. Al2 (SO4) 3 3. H2SO4 4. Cu (OH) 2 5. Al (NO3) 3 6. H3PO4 7. K2O 8. CuOH
Name of substance: A. Potassium oxide B. Phosphoric acid C. Copper (II) hydroxide D. Aluminum nitrate

Part B. Tasks with a free answer

13. For hydroxide (acid or base) write the formula of the corresponding oxide:
A. H2SO4 B. KOH B. Cu (OH) 2

14. Make up the chemical formulas of the compounds:
A. Silver (I) oxide B. Zinc hydroxide C. Sulfuric acid D. Aluminum chloride

15. Calculate the volume of CH4 methane gas produced from 500 liters of natural gas if the volume fraction of methane in natural gas is known to be 95%.

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 ones.

OXIDE	ACID	BASE	SALT
E x O y	NnA A - acid 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 valency equal to 2. Only one chemical element - fluorine, combining with oxygen, forms not an oxide, but oxygen fluoride OF 2.
They are called simply - "oxide + element name" (see table). If the valence of a chemical element is variable, then it is indicated by a Roman numeral enclosed in parentheses after the name of the chemical element.

Formula	Name	Formula	Name
	carbon monoxide (II)		iron (III) oxide
	nitric oxide (II)		chromium (VI) oxide
	aluminium oxide		zinc oxide
	nitric oxide (V)		manganese (VII) oxide

Classification of oxides

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

Metal oxides Me x O y			Nonmetal oxides notMe x O y
The main	Acidic	Amphoteric	Acidic	Indifferent
I, II Me	V-VII Me	ZnO, BeO, Al 2 O 3, Fe 2 O 3, Cr 2 O 3	> II not me	I, II not me

1). Basic oxides Are the oxides to which the bases correspond. Basic oxides include oxides metals 1 and 2 groups, as well metals side subgroups with valence I and II (except for ZnO - zinc oxide and BeO - beryllium oxide):

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

3). Amphoteric oxides- these are oxides, which correspond to bases and acids. These include metal oxides major and minor 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 nonmetal 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);

CrO 3 (Vii- acidic).

Classification of oxides

(by solubility in water)

Acidic oxides	Basic oxides	Amphoteric oxides
Soluble in water. Exception - SiO 2 (insoluble in water)	Only oxides of alkali and alkaline earth metals dissolve in water (these are metals I "A" and II "A" groups, excluding Be, Mg)	They do not interact with water. Insoluble in water

Complete tasks:

1. Write down separately the chemical formulas of salt-forming acid 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
	b) complex substances	2H 2 S + 3O 2 = 2H 2 O + 2SO 2
2.Decomposition of complex substances (use acid table, see appendices)	SALTt= BASIC OXIDE + ACID OXIDE	СaCO 3 = CaO + CO 2
	b) Insoluble bases Me (OH)bt= Me x O y+ H 2 O	Cu (OH) 2 t = CuO + H 2 O
	c) oxygenated 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 + Acidic oxide = Salt (p. Compound) CaO + SO 2 = CaSO 3 2. Basic oxide + Acid = Salt + H 2 O (p. Exchange) 3 K 2 O + 2 H 3 PO 4 = 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Water = Alkali (p. Compound) Na 2 O + H 2 O = 2 NaOH

CHEMICAL PROPERTIES OF ACID OXIDES 1. Acid oxide + Water = Acid (p. Compound) C O 2 + H 2 O = H 2 CO 3, SiO 2 - does not react 2. Acid oxide + Base = Salt + H 2 O (p. Exchange) P 2 O 5 + 6 KOH = 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Acidic oxide = Salt (p. Compound) CaO + SO 2 = CaSO 3 4. The less volatile displace the more volatile ones from their salts CaCO 3 + SiO 2 = CaSiO 3 + CO 2

CHEMICAL PROPERTIES OF AMPHOTHERIC 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 fusion)

Application of oxides

Some oxides do not dissolve in water, but many enter into a compound reaction with water:

SO 3 + H 2 O = H 2 SO 4

CaO + H 2 O = Ca(OH) 2

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

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

Titanium (IV) oxide - TiO 2 possesses the same valuable properties. It also has a beautiful white color and is used to make titanium white. TiO 2 does not dissolve not only in water, but also in acids; therefore, coatings made of this oxide are especially resistant. This oxide is added to the 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 crystals of dark green color, insoluble in water. Cr 2 O 3 is used as a pigment (paint) in the manufacture of decorative green glass and ceramics. The GOI paste known to many (abbreviated from 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 down separately the chemical formulas of salt-forming acid 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

Choose from the list: basic oxides, acidic oxides, indifferent oxides, amphoteric oxides and give them names.

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

Na 2 O + H 2 O =

N 2 O 5 + H 2 O =

CaO + HNO 3 =

NaOH + P 2 O 5 =

K 2 O + CO 2 =

Cu (OH) 2 =? +?

4. Carry out the transformations according to the scheme:

1) K → K 2 O → KOH → K 2 SO 4

2) S → SO 2 → H 2 SO 3 → Na 2 SO 3

3) P → P 2 O 5 → H 3 PO 4 → K 3 PO 4

Control test on the topic "Compound of chemical elements", grade 8. Option 2

Part A.

1. (3 points). A pure substance, as opposed to a mixture, is: A. Sea water. B. Milk. V. Air. G. Oxygen.

2 (3 points). A series of formulas in which everything is- entities - grounds:

A. C u (OH) 2, CuCl 2, NaOH. B. Ca (OH) 2, Mg (OH) 2, MgOHCI.

V... KOH, Ba (OH) 2, C u (OH) 2. G. HC l, NaOH, NaC l.

3 (3 points). Carbon exhibits the lowest ste- oxidation stump in conjunction with the formula:

A... CH 4. B. H 2 CO 3. V... CO 2. G. CO.

4 (3 points). The general formula of the oxide is depicted by a conditional notation:

A. M (OH) x. V. M x (KO) y

B. E x O U. G. H x KO.

M - metal, E - element, KO - acid residue.

5 (3 points). The number of salt formulas is in the following list: H 2 CO 3, Fe (OH) 3, KNO 3, NaOH, Ba (OH) 2, CaO, SO 2, CaC O 3 - equal to:

A.1 B.2 C.3 D.4

6 (3 points). Mass fraction of aluminum in aluminum oxide Al 2 Oz equals:

A. 52.94%. B. 0.36% C. 26.47% D. 73.00%

7 (3 points). 20 g of NaCl was dissolved in 180 g of water. The mass fraction of sodium chloride in the resulting solution is equal to:

A. 11%. B. 15%. V. 20%. G. 10%

8 (3 points). Copper chloride formula ( II):

A . CuCl B . Si 2 SO 4 V . CuCl 2. G. CuS O 4.

9 (3 points). The acid formula in which the charge of the ion of the acid residue is 3 -:

A... НС l. B. H 3 PO 4. V. H 2 SO 4. G. HNO 3.

10 (3 points). A water-insoluble base is a substance with the formula:

A... NaOH. B . KOH. V . Fe (OH) 3. G. Ba (OH) 2.

11 (6 points) Relate.

Compound Formula:

1. K 2 O. 2. CaSO 4. 3.H 2 SO 4. 4. KOH 5. SO 2 6. HNO 3

Connection class:

A. Oxides. B. Grounds. B. Acids. G. Salt.

12. (4 points) Correlate.

Compound Formula: 1. Mn CL 2 2. Fe (OH) 2 3. Fe (OH) 3 4. H 2 SO 4 5. MgCl 2 6. MgO 7. MnO Name of substance: A. Magnesium oxide. B. Sulfuric acid c. Iron (3) hydroxide d. Magnesium chloride

Part B Free answer tasks

13. (6 points) For a hydroxide (acid or base), write the formula of the corresponding oxide: A. H 2 SiO 3 B. Ca (OH) 2 B. Fe (OH) 3

14. (4 points)

Write the chemical formulas of the compounds: A. aluminum oxide (3) B. sodium nitrate C. potassium sulfate D. zinc hydroxide (2)

15. (6 points) Calculate the volume of nitrogen obtained from 200 liters of air if the volume fraction of nitrogen in the air is 78%.

Control test on the topic " Compound of chemical elements ",8th grade. Option 1

Part A. Test tasks with the choice of one correct answer and for correlation

1 (3 points). A mixture of substances, in contrast to an individual substance, is:A. Tap water.B ... Carbon dioxide.V. Oxygen. G. Copper

2 (3 points). A number of formulas in which all substances are oxides:A. ZnO, ZnCl 2, H 2 O. B. CaO, NaOH, NH 3 V. SO 3, MgO, CuO. G. KOH, K 2 O, MgO.

3 (3 points). Nitrogen exhibits the highest oxidation state when combined with the formula:A. NH 3. B. NO 2. V. N 2 O 5. G. NO.

4 (3 points). The general formula of the base is expressed- on a conditional record:

A. M (OH) x. B. E x O y. V... E x N y. G. H x KO M - metal, E - element, KO - acid residue.

5 (3 points). The number of acid formulas in the following list: H 2 CO 3, Fe (OH) 2, NaOH, H 2 SiO 3, Ba (OH) 2,
Cu (OH) 2, CaO, SO 2 - equal to: A. 1 ... B. 2 ... V. 3. G. 4.

6 (3 points). Mass fraction of sulfur in sulfuric acid Н 2 SO 4 is equal to: A . 2,04%. B. 65,31%. V. 52,34%. G . 32,65% .

7 (3 points). In 80 g of water, 20 g of salt was dissolved. The mass fraction of salt in the resulting solution is equal to:
A . 20% . B. 25% . V. 40% . G. 30% .

8 (3 points). Ferrous Sulfate Formula ( II): A. FeS. B . FeSO 3. V . Fe 2 (SO 4) 3 . G. FeSO 4

9 (3 points). The acid formula, in which the charge of the ion of the acid residue is 2 -:
A.НС l. B. H 2 SO 4. V... H 3 PO 4 ... G. HNO 3.

10 (3 points). Alkali is a substance with- mule:

A. A l (OH) h. B . F e (OH) 2 , . V . KOH . G. Cu (OH ) 2 .

11 (3 points). Relate.

Formula connections:

1. Na 2 O. 2 .M gS O 4 . 3 .NaOH. 4 . HCl. 5. CO 2 . 6 ... N 3 RO 4 .

Connection class:A. Oxides. B. Foundations. V. Acids. G. Salt.

12 (3 points). Relate.

Compound Formula:

1 ... HNO 3 . 2. A l 2 O 3 . 3. Ca (OH) 2 . 4. CaSO 4 . 5. Ca O . 6. H 3 PO 4 . 7. A l (OH) h. 8. TO 2 SO 4 .
Substance name:

A. Calcium oxide. B. Nitric acid.V. Aluminum hydroxide.G. Potassium sulfate.

Part B ... Free answer tasks

13 (6 points). For hydroxides (acid or base), write the formulas of the corresponding oxides:A. H 2 CO 3 . B. Mg (OH ) 2 ... V. Al (OH ) 3 .

14 (4 points). Make up the chemical formulas of the compounds:A. Potassium oxide. B ... Hydrochloric acid.V. Calcium phosphate. G. Barium hydroxide.

15 (6 points). Calculate the volume of oxygen obtained from 200 liters of air if the volume fraction of oxygen in the air is known to be 21%.

The key of the answers to the test.

Part A

Option 1

question

answer

A-1.5 B-4 C-3.6 G-2

A-6 B-4 C-3 D-5

Part A

Option 2

question

answer

A-1.5 B-3 C-4.6 G-2

А-5 B-1 В-7 Г-8

52-49 points score "5"

48-38 points score "4"

37-28 points score "3"

27 - 12 points score "2"