Chem properties of acid oxides. Chemical properties of water

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

OXIDE	ACID	BASE	SALT
E x O y	N  nA 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   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 oxygen, but OF 2 oxygen fluoride.
  They are called simply - "oxide + element name" (see table). If the valency of a chemical element is variable, it is indicated by a Roman numeral, enclosed in parentheses, after the name of the chemical element.

Formula	Title	Formula	Title
	carbon monoxide (II)	Fe 2 O 3	iron oxide (III)
	nitric oxide (II)	CrO 3	chromium oxide (VI)
Al 2 O 3	aluminium oxide		zinc oxide
N 2 O 5	nitric oxide (V)	Mn 2 O 7	manganese oxide (VII)

Oxide classification

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

Metal oxides Me x Oh y			Non-metal oxides heM 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 CO, NO, N 2 O

1). Basic oxidesAre the oxides to which the bases correspond. The main oxides include oxides of metals   1 and 2 groups, as well as of 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 include non-metal oxides   (except non-salt-forming - 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 oxide (VII)):

3). Amphoteric oxides  Are oxides to which bases and acids correspond. These include metal oxides   main and secondary subgroups with valency III sometimes IV as well as zinc and beryllium (e.g.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 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  - primary);

Cr 2 O 3 (III- amphoteric);

CrO 3 (VII  - acidic).

Oxide classification

(solubility in water)

Acid Oxides	Basic oxides	Amphoteric oxides
Soluble in water. Exception - SiO 2 (insoluble in water)	Only alkali and alkaline earth metal oxides 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 the 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 out the oxides and classify them.

Preparation of 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 acid table, see appendices)	a) salts SALT  t\u003d BASIC OXIDE + ACID OXIDE	CaCO 3 \u003d CaO + CO 2
	b) insoluble bases Me (OH)  b  t= Me x O y+ H 2 O	Cu (OH) 2 t \u003d CuO + H 2 O
	c) oxygen-containing acids N  nA \u003dACID 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 (s. Compounds) CaO + SO 2 \u003d CaSO 3 2. The main oxide + Acid \u003d Salt + H 2 O (s. Exchange) 3 K 2 O + 2 H 3 PO 4 \u003d 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Water \u003d Alkali (s. Compounds) Na 2 O + H 2 O \u003d 2 NaOH

CHEMICAL PROPERTIES OF ACID OXIDES 1. Acid oxide + Water \u003d Acid (s. 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 (s. Exchange) P 2 O 5 + 6 KOH \u003d 2 K 3 PO 4 + 3 H 2 O 3. Basic oxide + Acid oxide \u003d Salt (s. Compounds) CaO + SO 2 \u003d CaSO 3 4. Less volatile displace more volatile salts. CaCO 3 + SiO 2 \u003d CaSiO 3 + CO 2

CHEMICAL PROPERTIES OF AMPHOTERIC OXIDES Interact with both acids and alkalis. ZnO + 2 HCl \u003d ZnCl 2 + H 2 O ZnO + 2 NaOH + H 2 O \u003d Na 2 [Zn (OH) 4] (in solution) ZnO + 2 NaOH \u003d Na 2 ZnO 2 + H 2 O    (during fusion)

The use of oxides

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

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

Cao + H 2 O = Ca( OH) 2

The result is often very useful 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 too. For example, zinc oxide ZnO is a white substance; therefore, it is used for the preparation of white oil paints (zinc white). Since ZnO is practically insoluble in water, zinc surfaces can be used to paint any surface, including those exposed to atmospheric precipitation. Insolubility and non-toxicity allow the use of this oxide in the manufacture of cosmetic creams, powders. Pharmacists make it an astringent and drying powder for external use.

The same valuable properties are possessed by titanium oxide (IV) - TiO 2. It also has a beautiful white color and is used for the manufacture of titanium white. TiO 2 does not dissolve not only in water, but also in acids, therefore coatings of this oxide are especially stable. This oxide is added to the plastic to give it a white color. It is part of the 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 (short for “State Optical Institute”) is used for grinding and polishing optics, metal jewelry products.

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

Assignment Assignments

1. Write down separately the chemical formulas of the 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, acid oxides, indifferent oxides, amphoteric oxides and give them names.

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

Na 2 O + H 2 O \u003d

N 2 O 5 + H 2 O \u003d

CaO + HNO 3 \u003d

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

Modern chemical science represents a wide variety of industries, and each of them, in addition to the theoretical base, has great applied, practical value. Whatever you touch, everything is a chemical product. The main sections are inorganic and organic chemistry. Consider what the main classes of substances are inorganic and what properties they possess.

The main categories of inorganic compounds

These include the following:

1. Oxides
2. Salt.
3. Grounds.
4. Acids.

Each of the classes is represented by a wide variety of compounds of inorganic nature and is significant in almost any structure of human economic and industrial activity. All the main properties characteristic of these compounds, being in nature and obtaining are studied in the school chemistry course without fail, in grades 8-11.

There is a general table of oxides, salts, bases, acids, which presents examples of each of the substances and their state of aggregation, being in nature. Also shown are interactions describing chemical properties. However, we will consider each of the classes separately and in more detail.

Compound Group - Oxides

4. Reactions, as a result of which elements change CO

Me + n O + C \u003d Me 0 + CO

1. Reagent water: acid formation (SiO 2 exception)

KO + water \u003d acid

2. Reactions with reasons:

CO 2 + 2CsOH \u003d Cs 2 CO 3 + H 2 O

3. Reactions with basic oxides: salt formation

P 2 O 5 + 3MnO \u003d Mn 3 (PO 3) 2

4. Reactions OVR:

CO 2 + 2Ca \u003d C + 2CaO,

They exhibit double properties, interact according to the principle of the acid-base method (with acids, alkalis, basic oxides, acid oxides). They do not interact with water.

1. With acids: salt and water formation

AO + acid \u003d salt + H 2 O

2. With bases (alkalis): the formation of hydroxocomplexes

Al 2 O 3 + LiOH + water \u003d Li

3. Reactions with Acid Oxides: Preparation of Salts

FeO + SO 2 \u003d FeSO 3

4. Reactions with OO: salt formation, fusion

MnO + Rb 2 O \u003d double salt of Rb 2 MnO 2

5. Fusion reactions with alkalis and alkali metal carbonates: salt formation

Al 2 O 3 + 2LiOH \u003d 2LiAlO 2 + H 2 O

They do not form either acids or alkalis. They exhibit narrowly specific properties.

Each higher oxide formed by both metal and non-metal, dissolving in water, gives a strong acid or alkali.

Organic and inorganic acids

In the classical sound (based on the positions of ED - electrolytic dissociation - acids - these are compounds that dissociate into H + cations and anions of An - acid residues in an aqueous medium. However, acids have been thoroughly studied today under anhydrous conditions, so there are many different theories for hydroxides.

The empirical formulas of oxides, bases, acids, salts are composed only of symbols, elements and indices indicating their amount in a substance. For example, inorganic acids are expressed by the formula H + acid residue n-. Organic matter has a different theoretical mapping. In addition to the empirical one, a complete and reduced structural formula can be written for them, which will reflect not only the composition and quantity of the molecule, but also the order of arrangement of atoms, their relationship with each other and the main functional group for carboxylic acids — COOH.

In an inorganic, all acids are divided into two groups:

• oxygen-free - HBr, HCN, HCL and others;
• oxygen-containing (oxoacids) - HClO 3 and all where there is oxygen.

Inorganic acids are also classified by stability (stable or stable - everything except carbonic and sulfuric, unstable or unstable - carbonic and sulfuric). Acids can be strong in strength: sulfuric, hydrochloric, nitric, perchloric, and others, as well as weak: hydrogen sulfide, hypochlorous, and others.

Organic chemistry offers no such variety. Acids that are organic in nature are carboxylic acids. Their common feature is the presence of a functional group -COOH. For example, HCOOH (formic), CH 3 COOH (acetic), C 17 H 35 COOH (stearic) and others.

There are a number of acids that are especially carefully emphasized when considering this topic in a school chemistry course.

1. Salt.
2. Nitric
3. Phosphoric.
4. Hydrobromic.
5. Coal.
6. Hydrogen iodide.
7. Sulfur.
8. Acetic, or ethane.
9. Butane, or oily.
10. Benzoic.

These 10 acids in chemistry are the fundamental substances of the corresponding class both in the school course and in industry and syntheses in general.

Inorganic Acid Properties

The main physical properties should be attributed primarily to a different state of aggregation. After all, there are a number of acids having the form of crystals or powders (boric, phosphoric) under ordinary conditions. The vast majority of the known inorganic acids are different liquids. Boiling and melting points also vary.

Acids can cause severe burns, as they have the power to destroy organic tissue and skin. To detect acids use indicators:

• methyl orange (in an ordinary environment - orange, in acids - red),
• litmus (in neutral - violet, in acids - red) or some others.

The most important chemical properties include the ability to interact with both simple and complex substances.

  Chemical properties of inorganic acids

What interact with	Reaction example
1. With simple metal substances. Prerequisite: the metal must stand in the ECM to hydrogen, since the metals standing after hydrogen are not able to displace it from the composition of acids. The reaction always produces hydrogen in the form of gas and salt.
2. With the grounds. The result of the reaction is salt and water. Such reactions of strong acids with alkalis are called neutralization reactions.	Any acid (strong) + soluble base \u003d salt and water
3. With amphoteric hydroxides. Bottom line: salt and water.	2HNO 2 + beryllium hydroxide \u003d Be (NO 2) 2 (medium salt) + 2H 2 O
4. With basic oxides. Bottom line: water, salt.	2HCL + FeO \u003d iron (II) chloride + H 2 O
5. With amphoteric oxides. The final effect: salt and water.	2HI + ZnO \u003d ZnI 2 + H 2 O
6. With salts formed by weaker acids. Final effect: salt and weak acid.	2HBr + MgCO 3 \u003d magnesium bromide + H 2 O + CO 2

When interacting with metals, not all acids react equally. Chemistry (grade 9) in the school involves a very shallow study of such reactions, however, and at this level, the specific properties of concentrated nitric and sulfuric acid when interacting with metals are considered.

Hydroxides: alkalis, amphoteric and insoluble bases

Oxides, salts, bases, acids - all these classes of substances have a common chemical nature, due to the structure of the crystal lattice, as well as the mutual influence of atoms in the composition of the molecules. However, if for oxides a very specific definition could be given, then for acids and bases this is more difficult to do.

Just like acids, bases according to the theory of ED are called substances that can decompose in an aqueous solution into metal cations Me n + and anions of OH - hydroxo groups.

• Soluble or alkali (strong bases, changing. Formed by metals of groups I, II. Example: KOH, NaOH, LiOH (that is, elements of only the main subgroups are taken into account);
• Slightly soluble or insoluble (medium strength, not changing the color of the indicators). Example: magnesium hydroxide, iron (II), (III) and others.
• Molecular (weak bases, reversibly dissociate into molecular ions in an aqueous medium). Example: N 2 H 4, amines, ammonia.
• Amphoteric hydroxides (exhibit dual basic acid properties). Example: beryllium, zinc and so on.

Each presented group is studied in a school chemistry course in the "Foundations" section. Chemistry of grades 8–9 implies a detailed study of alkalis and sparingly soluble compounds.

The main characteristic properties of the bases

All alkalis and sparingly soluble compounds are in nature in a solid crystalline state. Moreover, their melting points are usually low, and sparingly soluble hydroxides decompose upon heating. The color of the bases is different. If the alkali is white, then the crystals of poorly soluble and molecular bases can be of very different colors. The solubility of most compounds of this class can be seen in the table, which shows the formulas of oxides, bases, acids, salts, their solubility is shown.

Alkalis are able to change the color of indicators as follows: phenolphthalein - raspberry, methyl orange - yellow. This is ensured by the free presence of hydroxo groups in solution. That is why sparingly soluble bases do not give such a reaction.

The chemical properties of each group of bases are different.

Chemical properties
Alkalis	Sparingly soluble bases	Amphoteric hydroxides
I. Interact with KO (total salt and water): 2LiOH + SO 3 \u003d Li 2 SO 4 + water II. Interact with acids (salt and water): conventional neutralization reactions (see acid) III. Interact with AO with the formation of a hydroxocomplex of salt and water: 2NaOH + Me + n O \u003d Na 2 Me + n O 2 + H 2 O, or Na 2 IV. Interact with amphoteric hydroxides with the formation of hydroxocomplex salts: The same as with AO, only without water V. Interact with soluble salts with the formation of insoluble hydroxides and salts: 3CsOH + iron (III) chloride \u003d Fe (OH) 3 + 3CsCl VI. Interact with zinc and aluminum in an aqueous solution with the formation of salts and hydrogen: 2RbOH + 2Al + water \u003d complex with hydroxide ion 2Rb + 3H 2	I. When heated, can decompose: insoluble hydroxide \u003d oxide + water II. Reactions with acids (total: salt and water): Fe (OH) 2 + 2HBr \u003d FeBr 2 + water III. Interact with CO: Me + n (OH) n + KO \u003d salt + H 2 O	I. React with acids to form salt and water:   (II) + 2HBr \u003d CuBr 2 + water II. React with alkalis: the result is salt and water (condition: fusion) Zn (OH) 2 + 2CsOH \u003d salt + 2H 2 O III. React with strong hydroxides: the result is salts, if the reaction proceeds in an aqueous solution: Cr (OH) 3 + 3RbOH \u003d Rb 3

These are the majority of the chemical properties that exhibit bases. Base chemistry is quite simple and obeys the general laws of all inorganic compounds.

Class of inorganic salts. Classification, physical properties

Based on the position of ED, salts can be called inorganic compounds that dissociate in an aqueous solution into metal cations Me + n and anions of acid residues An n-. So you can imagine the salt. Chemistry gives more than one definition, but it is the most accurate.

Moreover, by their chemical nature, all salts are divided into:

• Acidic (containing a hydrogen cation). Example: NaHSO 4.
• Basic (containing a hydroxy group). Example: MgOHNO 3, FeOHCL 2.
• Medium (consist only of a metal cation and an acid residue). Example: NaCL, CaSO 4.
• Double (include two different metal cations). Example: NaAl (SO 4) 3.
• Complex (hydroxocomplexes, aquacomplexes and others). Example: K 2.

The salt formulas reflect their chemical nature, and also talk about the qualitative and quantitative composition of the molecule.

Oxides, salts, bases, acids have different solubility, which can be seen in the corresponding table.

If we talk about the state of aggregation of salts, then you need to notice their uniformity. They exist only in a solid, crystalline or powder state. The color scheme is quite diverse. Solutions of complex salts, as a rule, have bright saturated colors.

Chemical interactions for the class of medium salts

They have similar chemical properties of base, acid, salt. Oxides, as we have already considered, are somewhat different from them in this factor.

In total, 4 main types of interactions for medium salts can be distinguished.

I. Interaction with acids (only strong in terms of ED) with the formation of another salt and a weak acid:

KCNS + HCL \u003d KCL + HCNS

II. Reactions with soluble hydroxides with the appearance of salts and insoluble bases:

CuSO 4 + 2LiOH \u003d 2LiSO 4 soluble salt + Cu (OH) 2 insoluble base

III. Interaction with another soluble salt to form an insoluble salt and soluble:

PbCL 2 + Na 2 S \u003d PbS + 2NaCL

IV. Reactions with metals standing in the ECMN to the left of what forms the salt. In this case, the metal entering the reaction should not under normal conditions interact with water:

Mg + 2AgCL \u003d MgCL 2 + 2Ag

These are the main types of interactions that are characteristic of medium salts. Formulas of salts of complex, basic, double and acidic speak for themselves about the specificity of the chemical properties shown.

The formulas of oxides, bases, acids, salts reflect the chemical essence of all representatives of these classes of inorganic compounds, and in addition, give an idea of \u200b\u200bthe name of the substance and its physical properties. Therefore, their writing should pay special attention. A huge variety of compounds offers us a generally amazing science - chemistry. Oxides, bases, acids, salts - this is only part of an immense variety.

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

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

with acidic compounds (acid oxides, acids) with the formation of salts and water:

CaO + CO 2 \u003d CaCO 3;

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

3) with amphoteric compounds:

Li 2 O + Al 2 O 3 \u003d 2 Li AlO 2;

3NaOH + Al (OH) 3 \u003d Na 3 AlO 3 + 3H 2 O;

Acid oxides react:

1) with water to form acids:

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

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

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

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

with amphoteric compounds

CO 2 + ZnO \u003d ZnCO 3;

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

Amphoteric oxides exhibit the properties of both basic and acidic oxides. Amphoteric hydroxides correspond to them:

acidic medium alkaline medium Be (OH) 2 BeO H 2 BeO 2

Zn (OH) 2 ZnO H 2 ZnO 2

Al (OH) 3 Al 2 O 3 H 3 AlO 3, HALO 2

Cr (OH) 3 Cr 2 O 3 HCrO 2

Pb (OH) 2 PbO H 2 PbO 2

Sn (OH) 2 SnO H 2 SnO 2

Amphoteric oxides interact with compounds of acidic and basic nature:

ZnO + SiO 2 \u003d ZnSiO 3; ZnO + H 2 SiO 3 \u003d ZnSiO 3 + H 2 O;

Al 2 O 3 + 3Na 2 O \u003d 2Na 3 AlO 3; Al 2 O 3 + 2NaOH \u003d 2NaAlO 2 + H 2 O.

Variable valence metals can form all three types of oxides. For example:

CrO basic Cr (OH) 2;

Cr 2 O 3 amphoteric Cr (OH) 3;

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

MnO, Mn 2 O 3 basic;

MnO 2 amphoteric;

Mn 2 O 7 acid HMnO 4.

Grounds

Bases - complex substances, which include metal atoms and one or more hydroxide groups (OH ‾). The general formula of the bases is Me (OH) y, where y is the number of hydroxide groups equal to the valency of the metal.

Nomenclature

The name of the base consists of the word "hydroxide" + the name of the metal.

If the metal has a variable valency, then it is indicated at the end in brackets. For example: CuOH - copper (I) hydroxide, Cu (OH) 2 - copper (II) hydroxide, NaOH - sodium hydroxide.

Bases (hydroxides) are electrolytes. Electrolytes are called substances that in melts or solutions of polar liquids decay into ions: positively charged cations and negatively charged anions. The decomposition of a substance into ions is called electrolytic dissociation.

All electrolytes can be divided into two groups: strong and weak. Strong electrolytes in aqueous solutions are almost completely dissociated. Weak electrolytes dissociate only partially and in solutions a dynamic equilibrium is established between undissociated molecules and ions: NH 4 OH NH 4 + + OH -.

2.2. Classification

a) by the number of hydroxide groups in the molecule. The amount of hydroxide groups in the base molecule depends on the valency of the metal and determines the acidity of the base.

The grounds are divided into:

Single acid, the molecules of which contain one hydroxide group: NaOH, KOH, LiOH and others;

Two-acid, the molecules of which contain two hydroxide groups: Ca (OH) 2, Fe (OH) 2, and others;

Three-acid, the molecules of which contain three hydroxide groups: Ni (OH) 3, Bi (OH) 3, etc.

Two- and three-acid bases are called multi-acid.

b) by the strength of the base are divided into:

Strong (alkalis): LiOH, NaOH, KOH, RbOH, CsOH, Ca (OH) 2, Sr (OH) 2, Ba (OH) 2;

Weak: Cu (OH) 2, Fe (OH) 2, Fe (OH) 3, etc.

Strong bases are soluble in water, and weak ones are insoluble.

Base dissociation

Strong bases dissociate almost completely:

Ca (OH) 2 \u003d Ca 2+ + 2OH -.

Weak bases dissociate stepwise. With the sequential cleavage of the hydroxide ion from multi-acid bases, the main residues of hydroxocations are formed, for example:

Fe (OH) 3 OH - + Fe (OH) 2 + iron dihydroxocations;

Fe (OH) 2 + OH - + FeOH 2+ iron hydroxocations;

Fe (OH) 2+ OH - + Fe 3+ iron cations.

The number of basic residues is equal to the acidity of the base.

Oxides

These are complex substances consisting of TWO elements, one of which is oxygen. For example:

CuO– copper (II) oxide

AI 2 O 3 - alumina

SO 3 - sulfur oxide (VI)

Oxides are divided (classified) into 4 groups:

Na 2 O– Sodium Oxide

CaO - Calcium Oxide

Fe 2 O 3 - iron oxide (III)

2). Acidic- These are oxides non-metals. And sometimes metals if the oxidation state of the metal is\u003e 4. For example:

CO 2 - Carbon Monoxide (IV)

P 2 O 5 - Phosphorus Oxide (V)

SO 3 - Sulfur oxide (VI)

3). Amphoteric- These are oxides that have properties of both basic and acidic oxides. You need to know the five most common amphoteric oxides:

BeO – beryllium oxide

ZnO– Zinc Oxide

AI 2 O 3 - Alumina

Cr 2 O 3 - Chromium (III) Oxide

Fe 2 O 3 - Iron (III) Oxide

4). Non-salt forming (indifferent)- These are oxides that do not exhibit the properties of either basic or acidic oxides. Three oxides must be remembered:

СО - carbon monoxide (II) carbon monoxide

NO– nitric oxide (II)

N 2 O– nitric oxide (I) laughing gas, nitrous oxide

Methods for producing oxides.

one). Burning, i.e. interaction with oxygen of a simple substance:

4Na + O 2 \u003d 2Na 2 O

4P + 5O 2 \u003d 2P 2 O 5

2). Burning, i.e. interaction with oxygen of a complex substance (consisting of two elements) are formed two oxides.

2ZnS + 3O 2 \u003d 2ZnO + 2SO 2

4FeS 2 + 11O 2 \u003d 2Fe 2 O 3 + 8SO 2

3). Decomposition threeweak acids. Others do not decompose. In this case, acid oxide and water are formed.

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

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

H 2 SiO 3 \u003d H 2 O + SiO 2

four). Decomposition insolublegrounds. Basic oxide and water are formed.

Mg (OH) 2 \u003d MgO + H 2 O

2Al (OH) 3 \u003d Al 2 O 3 + 3H 2 O

5). Decomposition insoluble  salts. The base oxide and acid oxide are formed.

CaCO 3 \u003d CaO + CO 2

MgSO 3 \u003d MgO + SO 2

Chemical properties.

I. Basic oxides.

alkali.

Na 2 O + H 2 O \u003d 2NaOH

CaO + H 2 O \u003d Ca (OH) 2

CuO + H 2 O \u003d reaction does not proceed, because possible base of which copper is insoluble

2). Interaction with acids, in this case salt and water are formed. (Basic oxide and acids react ALWAYS)

K 2 O + 2CHI \u003d 2KCl + H 2 O

CaO + 2HNO 3 \u003d Ca (NO 3) 2 + H 2 O

3). Interaction with acid oxides to form a salt.

Li 2 O + CO 2 \u003d Li 2 CO 3

3MgO + P 2 O 5 \u003d Mg 3 (PO 4) 2

four). Interaction with hydrogen, in this case, metal and water are formed.

CuO + H 2 \u003d Cu + H 2 O

Fe 2 O 3 + 3H 2 \u003d 2Fe + 3H 2 O

II.Acid Oxides.

one). Interaction with water, while it should be formed acid.(OnlySiO 2 does not interact with water)

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

P 2 O 5 + 3H 2 O \u003d 2H 3 PO 4

2). Interaction with soluble bases (alkalis). This forms salt and water.

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

N 2 O 5 + 2KOH \u003d 2KNO 3 + H 2 O

3). Interaction with basic oxides. In this case, only salt is formed.

N 2 O 5 + K 2 O \u003d 2KNO 3

Al 2 O 3 + 3SO 3 \u003d Al 2 (SO 4) 3

Basic exercises.

one). Complete the reaction equation. Determine its type.

K 2 O + P 2 O 5 \u003d

Decision.

In order to record what is formed as a result, it is necessary to determine which substances have reacted — here it is potassium oxide (basic) and phosphorus oxide (acid) according to the properties — the result should be SALT (see property No. 3) and the salt consists of atoms metals (in our case potassium) and an acid residue which contains phosphorus (i.e., PO 4 -3 - phosphate) Therefore

3K 2 O + P 2 O 5 \u003d 2K 3 PO 4

the type of reaction is the compound (since two substances enter into the reaction, and one is formed)

2). Carry out the transformation (chain).

Ca → CaO → Ca (OH) 2 → CaCO 3 → CaO

Decision

To complete this exercise, you need to remember that each arrow is one equation (one chemical reaction). We number each arrow. Therefore, it is necessary to write 4 equations. The substance recorded to the left of the arrow (starting material) reacts, and the substance recorded to the right - is formed as a result of the reaction (reaction product). Decrypt the first part of the record:

Ca + ... .. → CaO We note that a simple substance reacts, and an oxide is formed. Knowing the methods for producing oxides (No. 1), we conclude that in this reaction it is necessary to add – oxygen (O 2)

2Са + О 2 → 2СаО

We turn to the transformation number 2

CaO → Ca (OH) 2

CaO + ....... → Ca (OH) 2

We conclude that here it is necessary to apply the property of basic oxides - interaction with water, because only in this case does the base form from the oxide.

CaO + H 2 O → Ca (OH) 2

We turn to the transformation number 3

Ca (OH) 2 → CaCO 3

Ca (OH) 2 + ... .. \u003d CaCO 3 + .......

We conclude that here we are talking about carbon dioxide CO 2 because only when interacting with alkalis it forms a salt (see property No. 2 of acid oxides)

Ca (OH) 2 + CO 2 \u003d CaCO 3 + H 2 O

We turn to the transformation number 4

CaCO 3 → CaO

CaCO 3 \u003d ... .. CaO + .......

We conclude that more CO 2 is formed here, because CaCO 3 is an insoluble salt and it is upon decomposition of such substances that oxides are formed.

CaCO 3 \u003d CaO + CO 2

3). Which of the following substances does CO 2 interact with? Write the reaction equations.

BUT). Hydrochloric acid B). Sodium hydroxide B). Potassium oxide g). Water

D). Hydrogen E). Sulfur oxide (IV).

We determine that CO 2 is an acid oxide. And acidic oxides react with water, alkalis and basic oxides ... Therefore, from the list we select the answers B, C, D And it is with them that we write the reaction equations:

one). СО 2 + 2NaOH \u003d Na 2 CO 3 + H 2 O

2). CO 2 + K 2 O \u003d K 2 CO 3

Oxidescalled complex substances, the molecules of which include 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 ordinary 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 nonmetals, which, when reacted with water, form the corresponding acids, and when reacted 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), a salt is formed:

CuO + 2HCl → CuCl 2 + H 2 O.

As a result of chemical reactions, other salts can also 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 oxidessuch metal oxides are called, which correspond to hydroxides belonging to the class of bases. The main 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 to form 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 → 2 LiAlO 2.

If in the composition of the oxides the non-metal or metal exhibiting a higher valency (usually from IV to VII) is used as the second element, then such oxides will be acidic. Acid oxides (acid anhydrides) are called such oxides, which correspond to hydroxides belonging to the class of acids. This, 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 to form 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 the base 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 oxideincludes an element that has amphoteric properties. Amphoterism is understood to mean the ability of compounds to exhibit acidic and basic properties depending on 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.

In the interaction of zinc oxide with a solution of alkali (the same NaOH), another reaction proceeds:

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

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

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

Still have questions? Want to know more about oxides?
To get help of a tutor - register.
The first lesson is free!

site, with full or partial copying of the material, a link to the source is required.