Oxides classification methods of obtaining chemical properties. Acid oxides - preparation and chemical properties

Today we begin our acquaintance with the most important classes of inorganic compounds. Inorganic substances are divided by composition, as you already know, into simple and complex.

OXIDE	ACID	BASE	SALT
E x O y	HnA 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 valence 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 valency 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)	Fe2O3	iron(III) oxide
	nitric oxide (II)	CrO3	chromium(VI) oxide
Al2O3	aluminium oxide		zinc oxide
N 2 O 5	nitric oxide (V)	Mn2O7	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			Non-metal oxides neMe x O y
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 neMe	I, II neMe CO, NO, N 2 O

1). Basic oxides are oxides that correspond to bases. The main oxides are oxides metals 1 and 2 groups, as well as metals side subgroups with valency I and II (except ZnO - zinc oxide and BeO – beryllium oxide):

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

3). Amphoteric oxides are oxides, which correspond to bases and acids. These include metal oxides main and secondary subgroups with valency 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 are oxides that are indifferent to acids and bases. These include non-metal oxides with valency I and II (For example, N 2 O, NO, CO).

Conclusion: the nature of the properties of oxides primarily depends on the valency of the element.

For example, chromium oxides:

CrO(II- main);

Cr 2 O 3 (III- amphoteric);

CrO 3 (VII- acid).

Classification of oxides

(by solubility in water)

Acid 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 down 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. Substances are given : 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 by oxygen)	a) simple substances Training apparatus	2Mg + O 2 \u003d 2MgO
	b) complex substances	2H 2 S + 3O 2 \u003d 2H 2 O + 2SO 2
2. Decomposition of complex substances (use table of acids, see appendices)	a) salt SALTt= BASIC OXIDE + ACID OXIDE	CaCO 3 \u003d CaO + CO 2
	b) Insoluble bases Me(OH)bt= Me x O y+ H 2 O	Cu (OH) 2 t \u003d CuO + H 2 O
	c) oxygen-containing acids HnA=ACID OXIDE + H 2 O	H 2 SO 3 \u003d 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 \u003d Salt (r. compounds) CaO + SO 2 \u003d CaSO 3 2. Basic oxide + Acid \u003d Salt + H 2 O (r. exchange) 3 K 2 O + 2 H 3 PO 4 = 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Water \u003d Alkali (r. compounds) Na 2 O + H 2 O \u003d 2 NaOH

CHEMICAL PROPERTIES OF ACID OXIDES 1. Acid oxide + Water \u003d Acid (p. Compounds) With O 2 + H 2 O \u003d H 2 CO 3, SiO 2 - does not react 2. Acid oxide + Base \u003d Salt + H 2 O (r. exchange) P 2 O 5 + 6 KOH \u003d 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Acid oxide \u003d Salt (p. Compound) CaO + SO 2 \u003d CaSO 3 4. Less volatiles displace more volatiles from their salts CaCO 3 + SiO 2 \u003d 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 \u003d Na 2 [Zn (OH) 4] (in solution) ZnO + 2 NaOH = Na 2 ZnO 2 + H 2 O (when fused)

Application of oxides

Some oxides do not dissolve in water, but many react with water to combine:

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

CaO + H 2 O = Ca( Oh) 2

The result is often very 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, any surface can be painted with zinc white, 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 oxide (IV) - 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; therefore, coatings made of this oxide are particularly stable. This oxide is added to plastic to give it a white color. It is part of the enamels for metal and ceramic utensils.

Chromium oxide (III) - 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 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 by no means their only application.

Tasks for fixing

1. Write down 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. Substances are given : 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 name them.

3. Finish UCR, 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 \u003d

K 2 O + CO 2 \u003d

Cu (OH) 2 \u003d? +?

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

Chemical properties of the main classes of inorganic compounds

Acid oxides

1. Acid oxide + water \u003d acid (exception - SiO 2)
   SO 3 + H 2 O \u003d H 2 SO 4
   Cl 2 O 7 + H 2 O \u003d 2HClO 4
2. Acid oxide + alkali \u003d salt + water
   SO 2 + 2NaOH \u003d Na 2 SO 3 + H 2 O
   P 2 O 5 + 6KOH \u003d 2K 3 PO 4 + 3H 2 O
3. Acid oxide + basic oxide = salt
   CO 2 + BaO = BaCO 3
   SiO 2 + K 2 O \u003d K 2 SiO 3

   Basic oxides

   1. Basic oxide + water \u003d alkali (oxides of alkali and alkaline earth metals react)
      CaO + H 2 O \u003d Ca (OH) 2
      Na 2 O + H 2 O \u003d 2NaOH
   2. Basic oxide + acid = salt + water
      CuO + 2HCl \u003d CuCl 2 + H 2 O
      3K 2 O + 2H 3 PO 4 = 2K 3 PO 4 + 3H 2 O
   3. Basic oxide + acid oxide = salt
      MgO + CO 2 \u003d MgCO 3
      Na 2 O + N 2 O 5 \u003d 2NaNO 3

      Amphoteric oxides

      1. Amphoteric oxide + acid = salt + water
         Al 2 O 3 + 6HCl \u003d 2AlCl 3 + 3H 2 O
         ZnO + H 2 SO 4 \u003d ZnSO 4 + H 2 O
      2. Amphoteric oxide + alkali \u003d salt (+ water)
         ZnO + 2KOH \u003d K 2 ZnO 2 + H 2 O (More correct: ZnO + 2KOH + H 2 O \u003d K 2)
         Al 2 O 3 + 2NaOH = 2NaAlO 2 + H 2 O (More correct: Al 2 O 3 + 2NaOH + 3H 2 O = 2Na)
      3. Amphoteric oxide + acid oxide = salt
         ZnO + CO 2 = ZnCO 3
      4. Amphoteric oxide + basic oxide = salt (when fused)
         ZnO + Na 2 O \u003d Na 2 ZnO 2
         Al 2 O 3 + K 2 O \u003d 2KAlO 2
         Cr 2 O 3 + CaO \u003d Ca (CrO 2) 2

         acids

         1. Acid + basic oxide = salt + water
            2HNO 3 + CuO \u003d Cu (NO 3) 2 + H 2 O
            3H 2 SO 4 + Fe 2 O 3 \u003d Fe 2 (SO 4) 3 + 3H 2 O
         2. Acid + Amphoteric Oxide = Salt + Water
            3H 2 SO 4 + Cr 2 O 3 \u003d Cr 2 (SO 4) 3 + 3H 2 O
            2HBr + ZnO = ZnBr 2 + H 2 O
         3. Acid + base = salt + water
            H 2 SiO 3 + 2KOH \u003d K 2 SiO 3 + 2H 2 O
            2HBr + Ni(OH) 2 = NiBr 2 + 2H 2 O
         4. Acid + Amphoteric Hydroxide = Salt + Water
            3HCl + Cr(OH) 3 = CrCl 3 + 3H 2 O
            2HNO 3 + Zn(OH) 2 = Zn(NO 3) 2 + 2H 2 O
         5. Strong acid + salt of a weak acid = weak acid + salt of a strong acid
            2HBr + CaCO 3 \u003d CaBr 2 + H 2 O + CO 2
            H 2 S + K 2 SiO 3 \u003d K 2 S + H 2 SiO 3
         6. Acid + metal (located to the left of hydrogen in the voltage series) \u003d salt + hydrogen
            2HCl + Zn \u003d ZnCl 2 + H 2
            H 2 SO 4 (razb.) + Fe \u003d FeSO 4 + H 2
            Important: oxidizing acids (HNO 3 , conc. H 2 SO 4) react differently with metals.

         Amphoteric hydroxides

         1. Amphoteric Hydroxide + Acid = Salt + Water
            2Al(OH) 3 + 3H 2 SO 4 = Al 2 (SO 4) 3 + 6H 2 O
            Be(OH) 2 + 2HCl = BeCl 2 + 2H 2 O
         2. Amphoteric hydroxide + alkali \u003d salt + water (when fused)
            Zn(OH) 2 + 2NaOH = Na 2 ZnO 2 + 2H 2 O
            Al(OH) 3 + NaOH = NaAlO 2 + 2H 2 O
         3. Amphoteric hydroxide + alkali = salt (in aqueous solution)
            Zn(OH) 2 + 2NaOH \u003d Na 2
            Sn (OH) 2 + 2NaOH \u003d Na 2
            Be(OH) 2 + 2NaOH = Na 2
            Al(OH) 3 + NaOH = Na
            Cr(OH) 3 + 3NaOH = Na 3

            alkalis

            1. Alkali + acid oxide \u003d salt + water
               Ba (OH) 2 + N 2 O 5 \u003d Ba (NO 3) 2 + H 2 O
               2NaOH + CO 2 \u003d Na 2 CO 3 + H 2 O
            2. Alkali + acid \u003d salt + water
               3KOH + H 3 PO 4 = K 3 PO 4 + 3H 2 O
               Ba(OH) 2 + 2HNO 3 = Ba(NO 3) 2 + 2H 2 O
            3. Alkali + amphoteric oxide \u003d salt + water
               2NaOH + ZnO = Na 2 ZnO 2 + H 2 O (More correct: 2NaOH + ZnO + H 2 O = Na 2)
            4. Alkali + amphoteric hydroxide = salt (in aqueous solution)
               2NaOH + Zn(OH) 2 = Na 2
               NaOH + Al(OH) 3 = Na
            5. Alkali + soluble salt = insoluble base + salt
               Ca(OH) 2 + Cu(NO 3) 2 = Cu(OH) 2 + Ca(NO 3) 2
               3KOH + FeCl 3 \u003d Fe (OH) 3 + 3KCl
            6. Alkali + metal (Al, Zn) + water = salt + hydrogen
               2NaOH + Zn + 2H 2 O \u003d Na 2 + H 2
               2KOH + 2Al + 6H 2 O = 2K + 3H 2

               salt

               1. Salt of a Weak Acid + Strong Acid = Salt of a Strong Acid + Weak Acid
                  Na 2 SiO 3 + 2HNO 3 \u003d 2NaNO 3 + H 2 SiO 3
                  BaCO 3 + 2HCl \u003d BaCl 2 + H 2 O + CO 2 (H 2 CO 3)
               2. Soluble salt + soluble salt = insoluble salt + salt
                  Pb(NO 3) 2 + K 2 S = PbS + 2KNO 3
                  CaCl 2 + Na 2 CO 3 \u003d CaCO 3 + 2NaCl
               3. Soluble salt + alkali \u003d salt + insoluble base
                  Cu(NO 3) 2 + 2NaOH = 2NaNO 3 + Cu(OH) 2
                  2FeCl 3 + 3Ba(OH) 2 = 3BaCl 2 + 2Fe(OH) 3
               4. Soluble metal salt (*) + metal (**) = metal salt (**) + metal (*)
                  Zn + CuSO 4 \u003d ZnSO 4 + Cu
                  Cu + 2AgNO 3 \u003d Cu (NO 3) 2 + 2Ag
                  Important: 1) metal (**) must be in the voltage series to the left of metal (*), 2) metal (**) must NOT react with water.

                  You may also be interested in other sections of the Chemistry Handbook:

General formula of oxides: E x O y

Oxygen has the second highest electronegativity value (after fluorine), so most compounds of chemical elements with oxygen are oxides.

Salt-forming oxides include those oxides that are capable of reacting with acids or bases to form the corresponding salt and water. Salt-forming oxides include:

• basic oxides, which usually form metals with an oxidation state of +1, +2. React with acids, acid oxides, amphoteric oxides, water (alkali and alkaline earth metal oxides only). The basic oxide element becomes a cation in the resulting salt. Na₂O, CaO, MgO, CuO.
• acid oxides- oxides of non-metals, as well as metals in the oxidation state from +5 to +7. React with water, with alkalis, with basic oxides, with amphoteric oxides. The acid oxide element is part of the anion of the resulting salt. Mn 2 O 7, CrO 3, SO 3, N 2 O 5.
• amphoteric oxides, which form metals with an oxidation state of +3 to +5 (amphoteric oxides also include BeO, ZnO, PbO, SnO). React with acids, alkalis, acidic and basic oxides.

Non-salt-forming oxides do not interact with either acids or bases, respectively, do not form. N 2 O, NO, CO, SiO.

According to the IUPAC nomenclature, the names of oxides are made up 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 is capable of forming several oxides, then their names should indicate the degree of oxidation of the element (a Roman numeral in brackets after the name):

Fe 2 O 3 - iron oxide (III);

MnO 2 - manganese (IV) oxide.

It is allowed to use Latin prefixes to indicate the number of atoms of the elements included in the oxide molecule:

Na 2 O is disodium oxide;

CO is carbon monoxide;

CO 2 - carbon dioxide.

The trivial names of some oxides are also often used:

Examples of solving problems on the topic "formulas of oxides"

EXAMPLE 1

Exercise	What mass of manganese (IV) oxide is required to obtain 14.2 g of chlorine from hydrochloric acid?
Solution	Let's write the reaction equation: According to the reaction equation Let's find the amount of substance: Calculate the mass of manganese oxide (IV):
Answer	It is necessary to take 17.4 g of manganese (IV) oxide.

EXAMPLE 2

Exercise	When 16.74 g of divalent metal were oxidized, 21.54 g of oxide was formed. Identify the metal and calculate the equivalent masses of the metal and its oxide.
Solution	The mass of oxygen in metal oxide is:

Oxides are a very common type of compounds that are found in the earth's crust and in the universe in general.

Classification of oxides

Salt-forming oxides - These are oxides that form salts as a result of a chemical reaction. 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.

• • basic oxides (for example, sodium oxide Na2O, copper (II) oxide CuO): metal oxides, the oxidation state of which is I-II;
  • acidic oxides (for example, sulfur(VI) oxide SO3, nitric oxide(IV) NO2): metal oxides with oxidation state V-VII and non-metal oxides;
  • amphoteric oxides (for example, zinc oxide ZnO, aluminum oxide Al2O3): metal oxides with oxidation states III-IV and exceptions (ZnO, BeO, SnO, PbO).

Non-salt-forming oxides:

carbon monoxide(II) CO, nitric oxide(I) N2O, nitric oxide(II) NO, silicon oxide(II) SiO.

Basic properties of chemical oxides

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

Na2O + H2O → 2NaOH.

2.React with acidic oxides to form the corresponding salts

Na2O + SO3 → Na2SO4.

3.React with acids to form salt and water:

CuO + H2SO4 → CuSO4 + H2O.

4.React with amphoteric oxides:

Li2O + Al2O3 → 2LiAlO2.

Chemical properties of acid oxides

If the second element in the composition of oxides is a non-metal or a metal exhibiting a higher valency (usually 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. These are, for example, CO2, SO3, P2O5, N2O3, Cl2O5, Mn2O7, etc. They dissolve in water and alkalis, forming salt and water.

1.React with water to form acid:

SO3 + H2O → H2SO4.

But not all acidic oxides directly react with water (SiO2, etc.).

2.React with based oxides to form a salt:

CO2 + CaO → CaCO3

3.They react with alkalis to form salt and water:

CO2 + Ba(OH)2 → BaCO3 + H2O.

Chemical properties of amphoteric oxides

In this composition of the amphoteric oxide, there is an element that has amphoteric properties. Amphotericity is understood as the ability of compounds to exhibit acidic and basic properties, depending on the conditions.

1.React with acids to form salt and water:

ZnO + 2HCl → ZnCl2 + H2O.

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

ZnO + 2NaOH → Na2 ZnO2 + H2O.

Physical Properties

Liquid (SO3, Mn2O7); Solid (K2O, Al2O3, P2O5); Gaseous (CO2, NO2, SO2).

You can get oxides with ...

The interaction of simple substances (with the exception of inert gases, gold and platinum) with oxygen:

2H2 + O2 → 2H2O

2Cu + O2 → 2CuO

When alkali metals (except lithium), as well as strontium and barium, are burned in oxygen, peroxides and superoxides are formed:

2Na + O2 → Na2O2

Roasting or combustion of binary compounds in oxygen:

4FeS2 + 11O2 → 2Fe2O3 + 8SO2

CS2 + 3O2 → CO2 + 2SO2

2PH3 + 4O2 → P2O5 + 3H2O

Thermal decomposition of salts:

CaCO3 → CaO + CO2

2FeSO4 → Fe2O3 + SO2 + SO3

Thermal decomposition of bases or acids:

2Al(OH)3 → Al2O3 + 3H2O

4HNO3 → 4NO2 + O2 + 2H2O

Oxidation of lower oxides to higher ones and reduction of higher ones to lower ones:

4FeO + O2 → 2Fe2O3

Fe2O3 + CO → 2FeO + CO2

The interaction of some metals with water at high temperature:

Zn + H2O → ZnO + H2

The interaction of salts with acid oxides during the combustion of coke with the release of a volatile oxide:

Ca3(PO4)2 + 3SiO2 + 5C(coke) → 3CaSiO3 + 2P+5CO

The interaction of metals with oxidizing acids:

Zn + 4HNO3(conc.) → Zn(NO3)2 + 2NO2 + 2H2O

Under the action of water-removing substances on acids and salts:

2KClO4 + H2SO4(conc) → K2SO4 + Cl2O7 + H2O

The interaction of salts of weak unstable acids with stronger acids:

NaHCO3 + HCl → NaCl + H2O + CO2

Nomenclature of oxides

The word "oxide" followed by the name of the chemical element in the genitive case. When several oxides are formed, their names indicate its oxidation state with a Roman numeral in brackets immediately after the name. Other names of oxides are often used according to the number of oxygen atoms: if the oxide contains only one oxygen atom, then it is called monoxide, monoxide or nitrous if two - dioxide or dioxide, if three - then trioxide or trioxide etc.

Video lesson 2: Chemical properties of basic oxides

Lecture: Characteristic chemical properties of oxides: basic, amphoteric, acidic

oxides- binary compounds (complex substances) consisting of oxygen with an oxidation state of -2 and another element.

According to their chemical ability to form salts, all oxides are divided into two groups:

• salt-forming,
• non-salt-forming.

Salt-forming, in turn, are divided into three groups: basic, acidic, amphoteric. The non-salt-forming ones include carbon monoxide (II) CO, nitric oxide (I) N2O, nitric oxide (II) NO, silicon oxide (II) SiO.

Basic oxides- these are oxides that exhibit basic properties, formed by alkali and alkaline earth metals in oxidation states +1, +2, as well as transition metals in lower oxidation states.

Bases correspond to this group of oxides: K 2 O - KOH; BaO - Ba (OH) 2; La 2 O 3 - La (OH) 3.

Acid oxides- These are oxides that exhibit acidic properties, formed by typical non-metals, as well as some transition metals in oxidation states from +4 to +7.

Acids correspond to this group of oxides: SO 3 -H 2 SO 4; CO 2 - H 2 CO 3; SO 2 - H 2 SO 3, etc.

Amphoteric oxides- these are oxides that exhibit basic and acidic properties, formed by transition metals in oxidation states +3, +4. Excl.: ZnO, BeO, SnO, PbO.

This group of oxides corresponds to amphoteric bases: ZnO - Zn(OH) 2; Al 2 O 3 - Al (OH) 3.

Consider the chemical properties of oxides:

Reagent	Basic oxides	Amphoteric oxides	Acid oxides
Water	React. Example: CaO + H 2 O → Ca (OH) 2	do not react	React. Example: S O 3 + H 2 O → H 2 SO 4
Acid	React. Example: Fe 2 O 3 + 6HCl → 2FeCl 3 + 3H 2 O	React. Example: ZnO + 2HCl → ZnCl 2 + H 2 O	do not react
Base	do not react	React. Example: ZnO + 2NaOH + H 2 O → Na 2	React. Example: 2NaOH + SiO 2 → Na 2 SiO 3 + H 2 O
basic oxide	do not react	React. Example: ZnO + CaO → CaZnO 2	React. Example: SiO 2 + CaO → CaSiO 3
acid oxide	React. Example: CaO + CO 2 → CaCO 3	React. Example: ZnO + SiO 2 → ZnSiO 3	do not react
amphoteric oxide	React. Example: Li 2 O + Al 2 O 3 → 2LiAlO	React	React. Example: Al 2 O 3 + 3SO 3 → Al 2 (SO 4) 3

From the above table, the following can be summarized:

Basic oxides of the most active metals interact with water, forming strong bases - alkalis. Basic oxides of less active metals do not react with water under normal conditions. All oxides of this group always react with acids, forming salts and water. And they do not react with bases.

Acid oxides mostly react with water. But not everyone reacts under normal conditions. All oxides of this group react with bases, forming salts and water. They do not react with acids.

Basic and acidic oxides are able to react with each other, with the subsequent formation of a salt.

Amphoteric oxides have basic and acidic properties. Therefore, they react with both acids and bases to form salts and water. Amphoteric oxides react with acidic and basic oxides. They also interact with each other. Most often, these chemical reactions occur when heated to form salts.