What interacts with what and what comes out. Types of chemical reactions

The material world in which we live and of which we are a tiny part is one and at the same time infinitely diverse. The unity and diversity of the chemical substances of this world is most clearly manifested in the genetic connection of substances, which is reflected in the so-called genetic series. Let us highlight the most characteristic features of such series.

1. All substances in this series must be formed by one chemical element. For example, a series written using the following formulas:

2. Substances formed by the same element must belong to different classes, i.e., reflect different forms of its existence.

3. Substances that form the genetic series of one element must be connected by mutual transformations. Based on this feature, it is possible to distinguish between complete and incomplete genetic series.

For example, the above genetic series of bromine will be incomplete, incomplete. Here's the next row:

can already be considered complete: it began with the simple substance bromine and ended with it.

Summarizing the above, we can give the following definition of the genetic series.

Genetic series- this is a series of substances - representatives of different classes, which are compounds of one chemical element, connected by mutual transformations and reflecting the common origin of these substances or their genesis.

Genetic connection- a more general concept than the genetic series, which is, albeit a vivid, but particular manifestation of this connection, which is realized during any mutual transformations of substances. Then, obviously, the first given series of substances also fits this definition.

There are three types of genetic series:

The richest series of metals exhibits different oxidation states. As an example, consider the genetic series of iron with oxidation states +2 and +3:

Let us recall that to oxidize iron into iron (II) chloride, you need to take a weaker oxidizing agent than to obtain iron (III) chloride:

Similar to the metal series, the non-metal series with different oxidation states is richer in bonds, for example, the genetic series of sulfur with oxidation states +4 and +6:

Only the last transition can cause difficulty. Follow the rule: in order to obtain a simple substance from an oxidized compound of an element, you need to take for this purpose its most reduced compound, for example, a volatile hydrogen compound of a non-metal. In our case:

This reaction in nature produces sulfur from volcanic gases.

Likewise for chlorine:

3. The genetic series of the metal, which corresponds to amphoteric oxide and hydroxide,very rich in bonds, because depending on the conditions they exhibit either acidic or basic properties.

For example, consider the genetic series of zinc:

Genetic relationship between classes of inorganic substances

Characteristic are reactions between representatives of different genetic series. Substances from the same genetic series, as a rule, do not interact.

For example:
1. metal + non-metal = salt

Hg + S = HgS

2Al + 3I 2 = 2AlI 3

2. basic oxide + acidic oxide = salt

Li 2 O + CO 2 = Li 2 CO 3

CaO + SiO 2 = CaSiO 3

3. base + acid = salt

Cu(OH) 2 + 2HCl = CuCl 2 + 2H 2 O

FeCl 3 + 3HNO 3 = Fe(NO 3) 3 + 3HCl

salt acid salt acid

4. metal - main oxide

2Ca + O2 = 2CaO

4Li + O 2 =2Li 2 O

5. non-metal - acid oxide

S + O 2 = SO 2

4As + 5O 2 = 2As 2 O 5

6. basic oxide - base

BaO + H 2 O = Ba(OH) 2

Li 2 O + H 2 O = 2LiOH

7. acid oxide - acid

P 2 O 5 + 3H 2 O = 2H 3 PO 4

SO 3 + H 2 O =H 2 SO 4

The classification of inorganic substances is based on chemical composition– the simplest and most constant characteristic over time. The chemical composition of a substance shows which elements are present in it and in what numerical ratio for their atoms.

Elements They are conventionally divided into elements with metallic and non-metallic properties. The first of them are always included in cations multi-element substances (metal properties), the second - in the composition anions (non-metallic properties). In accordance with the Periodic Law, in periods and groups between these elements there are amphoteric elements that simultaneously exhibit, to one degree or another, metallic and non-metallic (amphoteric, dual) properties. Group VIIIA elements continue to be considered separately (noble gases), although clearly non-metallic properties were discovered for Kr, Xe and Rn (the elements He, Ne, Ar are chemically inert).

The classification of simple and complex inorganic substances is given in table. 6.

Below are definitions of classes of inorganic substances, their most important chemical properties and methods of preparation.

Inorganic substances– compounds formed by all chemical elements (except most organic carbon compounds). Divided by chemical composition:

Simple substances formed by atoms of the same element. Divided by chemical properties:

Metals– simple substances of elements with metallic properties (low electronegativity). Typical metals:

Metals have a high reducing power compared to typical non-metals. In the electrochemical series of voltages, they are significantly to the left of hydrogen, displacing hydrogen from water (magnesium - when boiling):

The simple substances of the elements Cu, Ag and Ni are also classified as metals, since their oxides CuO, Ag 2 O, NiO and hydroxides Cu(OH) 2, Ni(OH) 2 have predominant basic properties.

Nonmetals– simple substances of elements with non-metallic properties (high electronegativity). Typical non-metals: F 2, Cl 2, Br 2, I 2, O 2, S, N 2, P, C, Si.

Nonmetals have a high oxidizing capacity compared to typical metals.

Amphigenes– amphoteric simple substances formed by elements with amphoteric (dual) properties (electronegativity intermediate between metals and non-metals). Typical amphigenes: Be, Cr, Zn, Al, Sn, Pb.

Amphigenes have a lower reducing ability compared to typical metals. In the electrochemical series of voltages, they are adjacent to hydrogen on the left or stand behind it on the right.

Aerogens– noble gases, monatomic simple substances of group VIIIA elements: He, Ne, Ar, Kr, Xe, Rn. Of these, He, Ne and Ar are chemically passive (compounds with other elements are not obtained), and Kr, Xe and Rn exhibit some properties of non-metals with high electronegativity.

Complex substances formed by atoms of different elements. Divided by composition and chemical properties:

Oxides– compounds of elements with oxygen, the oxidation state of oxygen in oxides is always equal to (-II). Divided by composition and chemical properties:

The elements He, Ne and Ar do not form compounds with oxygen. Compounds of elements with oxygen in other oxidation states are not oxides, but binary compounds, for example O +II F 2 -I and H 2 +I O 2 -I. Mixed binary compounds, for example S +IV Cl 2 -I O -II, do not belong to oxides.

Basic oxides– products of complete dehydration (real or conditional) of basic hydroxides retain the chemical properties of the latter.

Of the typical metals, only Li, Mg, Ca and Sr form the oxides Li 2 O, MgO, CaO and SrO when burned in air; oxides Na 2 O, K 2 O, Rb 2 O, Cs 2 O and BaO are obtained by other methods.

The oxides of CuO, Ag 2 O and NiO are also classified as basic.

Acidic oxides– products of complete dehydration (real or conditional) of acid hydroxides retain the chemical properties of the latter.

Of the typical nonmetals, only S, Se, P, As, C and Si form the oxides SO 2, SeO 2, P 2 O 5, As 2 O 3, CO 2 and SiO 2 when burned in air; oxides Cl 2 O, Cl 2 O 7, I 2 O 5, SO 3, SeO 3, N 2 O 3, N 2 O 5 and As 2 O 5 are obtained by other methods.

Exception: the oxides NO 2 and ClO 2 do not have corresponding acidic hydroxides, but they are considered acidic, since NO 2 and ClO 2 react with alkalis, forming salts of two acids, and ClO 2 with water, forming two acids:

a) 2NO 2 + 2NaOH = NaNO 2 + NaNO 3 + H 2 O

b) 2ClO 2 + H 2 O (cold) = HClO 2 + HClO 3

2ClO 2 + 2NaOH (cold) = NaClO 2 + NaClO 3 + H 2 O

The oxides CrO 3 and Mn 2 O 7 (chromium and manganese in the highest oxidation state) are also acidic.

Amphoteric oxides– products of complete dehydration (real or conditional) of amphoteric hydroxides retain the chemical properties of amphoteric hydroxides.

Typical amphigenes (except Ga) when burned in air form the oxides BeO, Cr 2 O 3, ZnO, Al 2 O 3, GeO 2, SnO 2 and PbO; amphoteric oxides Ga 2 O 3, SnO and PbO 2 are obtained by other methods.

Double oxides are formed either by atoms of one amphoteric element in different oxidation states, or by atoms of two different (metallic, amphoteric) elements, which determines their chemical properties. Examples:

(Fe II Fe 2 III) O 4, (Pb 2 II Pb IV) O 4, (MgAl 2) O 4, (CaTi) O 3.

Iron oxide is formed when iron burns in air, lead oxide is formed when lead is slightly heated in oxygen; oxides of two different metals are prepared by other methods.

Non-salt-forming oxides– non-metal oxides that do not have acidic hydroxides and do not enter into salt formation reactions (difference from basic, acidic and amphoteric oxides), for example: CO, NO, N 2 O, SiO, S 2 O.

Hydroxides– compounds of elements (except fluorine and oxygen) with hydroxo groups O -II H, may also contain oxygen O -II. In hydroxides, the oxidation state of the element is always positive (from +I to +VIII). The number of hydroxo groups is from 1 to 6. They are divided according to chemical properties:

Basic hydroxides (bases) formed by elements with metallic properties.

Obtained by reactions of the corresponding basic oxides with water:

M 2 O + H 2 O = 2MON (M = Li, Na, K, Rb, Cs)

MO + H 2 O = M(OH) 2 (M = Ca, Sr, Ba)

Exception: Mg(OH) 2 , Cu(OH) 2 and Ni(OH) 2 hydroxides are obtained by other methods.

When heated, real dehydration (loss of water) occurs for the following hydroxides:

2LiOH = Li 2 O + H 2 O

M(OH) 2 = MO + H 2 O (M = Mg, Ca, Sr, Ba, Cu, Ni)

Basic hydroxides replace their hydroxo groups with acidic residues to form salts; metal elements retain their oxidation state in salt cations.

Basic hydroxides that are highly soluble in water (NaOH, KOH, Ca(OH) 2, Ba(OH) 2, etc.) are called alkalis, since it is with their help that an alkaline environment is created in the solution.

Acidic hydroxides (acids) formed by elements with non-metallic properties. Examples:

Upon dissociation in a dilute aqueous solution, H + cations (more precisely, H 3 O +) and the following anions are formed, or acid residues:

Acids can be obtained by reactions of the corresponding acid oxides with water (the actual reactions that occur are shown below):

Cl 2 O + H 2 O = 2HClO

E 2 O 3 + H 2 O = 2HEO 2 (E = N, As)

As 2 O 3 + 3H 2 O = 2H 3 AsO 3

EO 2 + H 2 O = H 2 EO 3 (E = C, Se)

E 2 O 5 + H 2 O = 2HEO 3 (E = N, P, I)

E 2 O 5 + 3H 2 O = 2H 3 EO 4 (E = P, As)

EO 3 + H 2 O = H 2 EO 4 (E = S, Se, Cr)

E 2 O 7 + H 2 O = 2HEO 4 (E = Cl, Mn)

Exception: SO 2 oxide corresponds to SO 2 polyhydrate as an acid hydroxide n H 2 O (“sulfurous acid H 2 SO 3 ”does not exist, but the acidic residues HSO 3 - and SO 3 2- are present in the salts).

When some acids are heated, actual dehydration occurs and the corresponding acid oxides are formed:

2HAsO 2 = As 2 O 3 + H 2 O

H 2 EO 3 = EO 2 + H 2 O (E = C, Si, Ge, Se)

2HIO 3 = I 2 O 5 + H 2 O

2H 3 AsO 4 = As 2 O 5 + H 2 O

H 2 SeO 4 = SeO 3 + H 2 O

When replacing the (real and formal) hydrogen of acids with metals and amphigenes, salts are formed; the acid residues retain their composition and charge in the salts. The acids H 2 SO 4 and H 3 PO 4 in a dilute aqueous solution react with metals and amphigens located in the voltage series to the left of hydrogen, and the corresponding salts are formed and hydrogen is released (the acid HNO 3 does not enter into such reactions; below are typical metals, except Mg, not listed because they react under similar conditions with water):

M + H 2 SO 4 (pasb.) = MSO 4 + H 2 ^ (M = Be, Mg, Cr, Mn, Zn, Fe, Ni)

2M + 3H 2 SO 4 (dissolved) = M 2 (SO 4) 3 + 3H 2 ^ (M = Al, Ga)

3M + 2H 3 PO 4 (diluted) = M 3 (PO 4) 2 v + 3H 2 ^ (M = Mg, Fe, Zn)

Unlike oxygen-free acids, acid hydroxides are called oxygen-containing acids or oxoacids.

Amphoteric hydroxides formed by elements with amphoteric properties. Typical amphoteric hydroxides:

Be(OH) 2 Sn(OH) 2 Al(OH) 3 AlO(OH)

Zn(OH) 2 Pb(OH) 2 Cr(OH) 3 CrO(OH)

They are not formed from amphoteric oxides and water, but undergo real dehydration and form amphoteric oxides:

Exception: for iron(III) only metahydroxide FeO(OH) is known, “iron(III) hydroxide Fe(OH) 3 ” does not exist (not obtained).

Amphoteric hydroxides exhibit the properties of basic and acidic hydroxides; form two types of salts in which the amphoteric element is part of either the salt cations or their anions.

For elements with several oxidation states, the rule applies: the higher the oxidation state, the more pronounced the acidic properties of hydroxides (and/or corresponding oxides).

Salts– connections consisting of cations basic or amphoteric (as basic) hydroxides and anions(residues) of acidic or amphoteric (as acidic) hydroxides. In contrast to oxygen-free salts, the salts discussed here are called oxygen-containing salts or oxo salts. They are divided according to the composition of cations and anions:

Medium salts contain medium acidic residues CO 3 2-, NO 3-, PO 4 3-, SO 4 2-, etc.; for example: K 2 CO 3, Mg(NO 3) 2, Cr 2 (SO 4) 3, Zn 3 (PO 4) 2.

If medium salts are obtained by reactions involving hydroxides, then the reagents are taken in equivalent quantities. For example, salt K 2 CO 3 can be obtained by taking the reagents in the following ratios:

2KOH and 1H 2 CO 3, 1K 2 O and 1H 2 CO 3, 2 KOH and 1CO 2.

Reactions of formation of medium salts:

Base + Acid > Salt + Water

1a) basic hydroxide + acidic hydroxide >...

2NaOH + H 2 SO 4 = Na 2 SO 4 + 2H 2 O

Cu(OH) 2 + 2HNO 3 = Cu(NO 3) 2 + 2H 2 O

1b) amphoteric hydroxide + acid hydroxide >...

2Al(OH) 3 + 3H 2 SO 4 = Al 2 (SO 4) 3 + 6H 2 O

Zn(OH) 2 + 2HNO 3 = Zn(NO 3) 2 + 2H 2 O

1c) basic hydroxide + amphoteric hydroxide >...

NaOH + Al(OH) 3 = NaAlO 2 + 2H 2 O (in melt)

2NaOH + Zn(OH) 2 = Na 2 ZnO 2 + 2H 2 O (in melt)

Basic Oxide + Acid = Salt + Water

2a) basic oxide + acidic hydroxide >...

Na 2 O + H 2 SO 4 = Na 2 SO 4 + H 2 O

CuO + 2HNO 3 = Cu(NO 3) 2 + H 2 O

2b) amphoteric oxide + acid hydroxide >...

Al 2 O 3 + 3H 2 SO 4 = Al 2 (SO 4) 3 + 3H 2 O

ZnO + 2HNO 3 = Zn(NO 3) 2 + H 2 O

2c) basic oxide + amphoteric hydroxide >...

Na 2 O + 2Al(OH) 3 = 2NaAlO 2 + ZN 2 O (in the melt)

Na 2 O + Zn(OH) 2 = Na 2 ZnO 2 + H 2 O (in melt)

Base + Acid Oxide > Salt + Water

For) basic hydroxide + acidic oxide >...

2NaOH + SO 3 = Na 2 SO 4 + H 2 O

Ba(OH) 2 + CO 2 = BaCO 3 + H 2 O

3b) amphoteric hydroxide + acid oxide >...

2Al(OH) 3 + 3SO 3 = Al 2 (SO 4) 3 + 3H 2 O

Zn(OH) 2 + N 2 O 5 = Zn(NO 3) 2 + H 2 O

Sv) basic hydroxide + amphoteric oxide >...

2NaOH + Al 2 O 3 = 2NaAlO 2 + H 2 O (in melt)

2NaOH + ZnO = Na 2 ZnO 2 + H 2 O (in melt)

Basic oxide + Acidic oxide > Salt

4a) basic oxide + acidic oxide >...

Na 2 O + SO 3 = Na 2 SO 4, BaO + CO 2 = BaCO 3

4b) amphoteric oxide + acidic oxide >...

Al 2 O 3 + 3SO 3 = Al 2 (SO 4) 3, ZnO + N 2 O 5 = Zn(NO 3) 2

4c) basic oxide + amphoteric oxide >...

Na 2 O + Al 2 O 3 = 2NaAlO 2, Na 2 O + ZnO = Na 2 ZnO 2

Reactions 1c, if they occur in solution, are accompanied by the formation of other products - complex salts:

NaOH (conc.) + Al(OH) 3 = Na

KOH (conc.) + Cr(OH) 3 = K 3

2NaOH (conc.) + M(OH) 2 = Na 2 (M = Be, Zn)

KOH (conc.) + M(OH) 2 = K (M = Sn, Pb)

All medium salts in solution are strong electrolytes (dissociate completely).

Acid salts contain acidic acid residues (with hydrogen) HCO 3 -, H 2 PO 4 2-, HPO 4 2-, etc., are formed by the action of basic and amphoteric hydroxides or medium salts of excess acid hydroxides containing at least two hydrogen atoms in the molecule ; The corresponding acid oxides act similarly:

NaOH + H 2 SO 4 (conc.) = NaHSO 4 + H 2 O

Ba(OH) 2 + 2H 3 PO 4 (conc.) = Ba(H 2 PO 4) 2 + 2H 2 O

Zn(OH) 2 + H 3 PO 4 (conc.) = ZnHPO 4 v + 2H 2 O

PbSO 4 + H 2 SO 4 (conc.) = Pb(HSO 4) 2

K 2 HPO 4 + H 3 PO 4 (conc.) = 2KH 2 PO 4

Ca(OH) 2 + 2EO 2 = Ca(HEO 3) 2 (E = C, S)

Na 2 EO 3 + EO 2 + H 2 O = 2NaHEO 3 (E = C, S)

By adding the hydroxide of the corresponding metal or amphigene, the acid salts are converted to medium salts:

NaHSO 4 + NaOH = Na 2 SO 4 + H 2 O

Pb(HSO 4) 2 + Pb(OH) 2 = 2PbSO 4 v + 2H 2 O

Almost all acid salts are highly soluble in water and dissociate completely (KHSO 3 = K + + HCO 3 -).

Basic salts contain OH hydroxo groups, considered as individual anions, for example FeNO 3 (OH), Ca 2 SO 4 (OH) 2, Cu 2 CO 3 (OH) 2, are formed when exposed to acid hydroxides excess a basic hydroxide containing at least two hydroxo groups in the formula unit:

Co(OH) 2 + HNO 3 = CoNO 3 (OH)v + H 2 O

2Ni(OH) 2 + H 2 SO 4 = Ni 2 SO 4 (OH) 2 v + 2H 2 O

2Cu(OH) 2 + H 2 CO 3 = Cu 2 CO 3 (OH) 2 v + 2H 2 O

Basic salts formed by strong acids, when adding the corresponding acid hydroxide, turn into medium salts:

CoNO 3 (OH) + HNO 3 = Co(NO 3) 2 + H 2 O

Ni 2 SO 4 (OH) 2 + H 2 SO 4 = 2NiSO 4 + 2H 2 O

Most basic salts are slightly soluble in water; they precipitate during joint hydrolysis if they are formed by weak acids:

2MgCl 2 + H 2 O + 2Na 2 CO 3 = Mg 2 CO 3 (OH) 2 v + CO 2 ^ + 4NaCl

Double salts contain two chemically different cations; for example: CaMg(CO 3) 2, KAl(SO 4) 2, Fe(NH 4) 2 (SO 4) 2, LiAl(SiO 3) 2. Many double salts are formed (in the form of crystalline hydrates) by co-crystallization of the corresponding intermediate salts from a saturated solution:

K 2 SO 4 + MgSO 4 + 6H 2 O = K 2 Mg(SO 4) 2 6H 2 Ov

Often double salts are less soluble in water compared to single salts.

Binary compounds- these are complex substances that do not belong to the classes of oxides, hydroxides and salts and consist of cations and oxygen-free anions (real or conditional).

Their chemical properties are varied and are considered in inorganic chemistry separately for nonmetals of different groups of the Periodic Table; in this case, classification is carried out according to the type of anion.

Examples:

A) halides: OF 2, HF, KBr, PbI 2, NH 4 Cl, BrF 3, IF 7

b) chalgogenides: H 2 S, Na 2 S, ZnS, As 2 S 3, NH 4 HS, K 2 Se, NiSe

V) nitrides: NH 3, NH 3 H 2 O, Li 3 N, Mg 3 N 2, AlN, Si 3 N 4

G) carbides: CH 4, Be 2 C, Al 4 C 3, Na 2 C 2, CaC 2, Fe 3 C, SiC

d) silicides: Li 4 Si, Mg 2 Si, ThSi 2

e) hydrides: LiH, CaH 2, AlH 3, SiH 4

and) peroxide H 2 O 2, Na 2 O 2, CaO 2

h) superoxides: HO 2, KO 2, Ba(O 2) 2

Based on the type of chemical bond, these binary compounds are distinguished:

covalent: OF 2, IF 7, H 2 S, P 2 S 5, NH 3, H 2 O 2

ionic: Nal, K 2 Se, Mg 3 N 2, CaC 2, Na 2 O 2, KO 2

Meet double(with two different cations) and mixed(with two different anions) binary compounds, for example: KMgCl 3, (FeCu)S 2 and Pb(Cl)F, Bi(Cl)O, SCl 2 O 2, As(O)F 3.

All ionic complex salts (except hydroxo complex salts) also belong to this class of complex substances (although usually considered separately), for example:

SO 4 K 4 Na 3

Cl K 3 K 2

Binary compounds include covalent complex compounds without an outer sphere, for example [N(CO) 4 ].

By analogy with the relationship between hydroxides and salts, oxygen-free acids and salts are isolated from all binary compounds (the remaining compounds are classified as others).

Anoxic acids contain (like oxoacids) mobile hydrogen H + and therefore exhibit some chemical properties of acid hydroxides (dissociation in water, participation in salt formation reactions as an acid). Common oxygen-free acids are HF, HCl, HBr, HI, HCN and H 2 S, of which HF, HCN and H 2 S are weak acids, and the rest are strong.

Examples salt formation reactions:

2HBr + ZnO = ZnBr 2 + H 2 O

2H 2 S + Ba(OH) 2 = Ba(HS) 2 + 2H 2 O

2HI + Pb(OH) 2 = Pbl 2 v + 2H 2 O

Metals and amphigenes, which are in the voltage series to the left of hydrogen and do not react with water, interact with strong acids HCl, HBr and HI (in the general form NG) in a dilute solution and displace hydrogen from them (actually occurring reactions are shown):

M + 2NG = MG 2 + H 2 ^ (M = Be, Mg, Zn, Cr, Mn, Fe, Co, Ni)

2M + 6NG = 2MG 3 + H 2 ^ (M = Al, Ga)

Oxygen-free salts formed by metal and amphigen cations (as well as the ammonium cation NH 4 +) and anions (residues) of oxygen-free acids; examples: AgF, NaCl, KBr, PbI 2, Na 2 S, Ba(HS) 2, NaCN, NH 4 Cl. They exhibit some chemical properties of oxo salts.

The general method for obtaining oxygen-free salts with single-element anions is the interaction of metals and amphigens with non-metals F 2, Cl 2, Br 2 and I 2 (in general form G 2) and sulfur S (actually occurring reactions are shown):

2M + G 2 = 2MG (M = Li, Na, K, Rb, Cs, Ag)

M + G 2 = MG 2 (M = Be, Mg, Ca, Sr, Ba, Zn, Mn, Co)

2M + ZG 2 = 2MG 3 (M = Al, Ga, Cr)

2M + S = M 2 S (M = Li, Na, K, Rb, Cs, Ag)

M + S = MS (M = Be, Mg, Ca, Sr, Ba, Zn, Mn, Fe, Co, Ni)

2M + 3S = M 2 S 3 (M = Al, Ga, Cr)

Exceptions:

a) Cu and Ni react only with the halogens Cl 2 and Br 2 (products MCl 2, MBr 2)

b) Cr and Mn react with Cl 2, Br 2 and I 2 (products CrCl 3, CrBr 3, CrI 3 and MnCl 2, MnBr 2, MnI 2)

c) Fe reacts with F 2 and Cl 2 (products FeF 3, FeCl 3), with Br 2 (a mixture of FeBr 3 and FeBr 2), with I 2 (product FeI 2)

d) Cu reacts with S to form a mixture of products Cu 2 S and CuS

Other binary compounds– all substances of this class, except those allocated to separate subclasses of oxygen-free acids and salts.

The methods for obtaining binary compounds of this subclass are varied, the simplest is the interaction of simple substances (reactions that actually occur are shown):

a) halides:

S + 3F 2 = SF 6, N 2 + 3F 2 = 2NF 3

2P + 5G 2 = 2RG 5 (G = F, CI, Br)

C + 2F 2 = CF 4

Si + 2G 2 = Sir 4 (G = F, CI, Br, I)

b) chalcogenides:

2As + 3S = As 2 S 3

2E + 5S = E 2 S 5 (E = P, As)

E + 2S = ES 2 (E = C, Si)

c) nitrides:

3H 2 + N 2 2NH 3

6M + N 2 = 2M 3 N (M = Li, Na, K)

3M + N 2 = M 3 N 2 (M = Be, Mg, Ca)

2Al + N 2 = 2AlN

3Si + 2N 2 = Si 3 N 4

d) carbides:

2M + 2C = M 2 C 2 (M = Li, Na)

2Be + C = Be 2 C

M + 2C = MC 2 (M = Ca, Sr, Ba)

4Al + 3C = Al 4 C 3

e) silicides:

4Li + Si = Li 4 Si

2M + Si = M 2 Si (M = Mg, Ca)

f) hydrides:

2M + H 2 = 2MH (M = Li, Na, K)

M + H 2 = MH 2 (M = Mg, Ca)

g) peroxides, superoxides:

2Na + O 2 = Na 2 O 2 (combustion in air)

M + O 2 = MO 2 (M = K, Rb, Cs; combustion in air)

Many of these substances completely react with water (they are often hydrolyzed without changing the oxidation states of the elements, but hydrides act as reducing agents, and superoxides enter into dismutation reactions):

PCl 5 + 4H 2 O = H 3 PO 4 + 5HCl

SiBr 4 + 2H 2 O = SiO 2 v + 4HBr

P 2 S 5 + 8H 2 O = 2H 3 PO 4 + 5H 2 S^

SiS 2 + 2H 2 O = SiO 2 v + 2H 2 S

Mg 3 N 2 + 8H 2 O = 3Mg(OH) 2 v + 2(NH 3 H 2 O)

Na 3 N + 4H 2 O = 3NaOH + NH 3 H 2 O

Be 2 C + 4H 2 O = 2Be(OH) 2 v + CH 4 ^

MC 2 + 2H 2 O = M(OH) 2 + C 2 H 2 ^ (M = Ca, Sr, Ba)

Al 4 C 3 + 12H 2 O = 4Al(OH) 3 v + 3CH 4 ^

MH + H 2 O = MOH + H 2 ^ (M = Li, Na, K)

MgH 2 + 2H 2 O = Mg(OH) 2 v + H 2 ^

CaH 2 + 2H 2 O = Ca(OH) 2 + H 2 ^

Na 2 O 2 + 2H 2 O = 2NaOH + H 2 O 2

2MO 2 + 2H 2 O = 2MOH + H 2 O 2 + O 2 ^ (M = K, Rb, Cs)

Other substances, on the contrary, are resistant to water, including SF 6, NF 3, CF 4, CS 2, AlN, Si 3 N 4, SiC, Li 4 Si, Mg 2 Si and Ca 2 Si.

1. Simple substances are

1) fullerene

2. In formula units of reaction products

Si + CF1 2 >…, Si + O 2 >…, Si + Mg >…

3. In metal-containing reaction products

Na + H 2 O >…, Ca + H 2 O >…, Al + НCl (solution) >…

the total sum of the number of atoms of all elements is equal to

4. Calcium oxide can react (separately) with all substances in the set

1) CO 2, NaOH, NO

2) HBr, SO 3, NH 4 Cl

3) BaO, SO 3, KMgCl 3

4) O 2, Al 2 O 3, NH 3

5. A reaction will take place between sulfur oxide (IV) and

6. Salt МAlO 2 is formed during fusion

2) Al 2 O 3 and KOH

3) Al and Ca(OH) 2

4) Al 2 O 3 and Fe 2 O 3

7. In the molecular equation of the reaction

ZnO + HNO 3 > Zn(NO 3) 2 +…

the sum of the coefficients is equal

8. The products of the reaction N 2 O 5 + NaOH >... are

1) Na 2 O, HNO 3

3) NaNO 3, H 2 O

4) NaNO 2, N 2, H 2 O

9. A set of bases is

1) NaOH, LiOH, ClOH

2) NaOH, Ba(OH) 2, Cu(OH) 2

3) Ca(OH) 2, KOH, BrOH

4) Mg(OH) 2 , Be(OH) 2 , NO(OH)

10. Potassium hydroxide reacts in solution (separately) with the substances of the set

4) SO 3, FeCl 3

11–12. The residue corresponding to the acid with the name

11. Sulfuric

12. Nitrogen

has the formula

13. From hydrochloric and dilute sulfuric acids doesn't highlight gas only metal

14. Amphoteric hydroxide is

15-16. According to given hydroxide formulas

15. H 3 PO 4, Pb(OH) 2

16. Cr(OH) 3 , HNO 3

the formula for the average salt is derived

1) Pb 3 (PO 4) 2

17. After passing excess H 2 S through a solution of barium hydroxide, the final solution will contain salt

18. Possible reactions:

1) CaSO 3 + H 2 SO 4 >...

2) Ca(NO 3) 2 + HNO 3 >...

3) NaHCOg + K 2 SO 4 >...

4) Al(HSO 4) 3 + NaOH >...

19. In the reaction equation (CaOH) 2 CO 3 (t) + H 3 PO 4 > CaHPO 4 v +…

the sum of the coefficients is equal

20. Establish a correspondence between the formula of a substance and the group to which it belongs.

21. Establish a correspondence between the starting materials and reaction products.

22. In the transformation scheme

substances A and B are indicated in the set

1) NaNO 3, H 2 O

4) HNO 3, H 2 O

23. Make up equations for possible reactions according to the diagram

FeS > H 2 S + PbS > PbSO 4 > Pb(HSO 4) 2

24. Write down equations for four possible reactions between substances:

1) nitric acid (conc.)

2) carbon (graphite or coke)

3) calcium oxide

During chemical reactions, one substance turns into another (not to be confused with nuclear reactions, in which one chemical element is converted into another).

Any chemical reaction is described by a chemical equation:

Reactants → Reaction products

The arrow indicates the direction of the reaction.

For example:

In this reaction, methane (CH 4) reacts with oxygen (O 2), resulting in the formation of carbon dioxide (CO 2) and water (H 2 O), or more precisely, water vapor. This is exactly the reaction that happens in your kitchen when you light a gas burner. The equation should be read like this: One molecule of methane gas reacts with two molecules of oxygen gas to produce one molecule of carbon dioxide and two molecules of water (water vapor).

The numbers placed before the components of a chemical reaction are called reaction coefficients.

Chemical reactions happen endothermic(with energy absorption) and exothermic(with energy release). Methane combustion is a typical example of an exothermic reaction.

There are several types of chemical reactions. The most common:

• connection reactions;
• decomposition reactions;
• single replacement reactions;
• double displacement reactions;
• oxidation reactions;
• redox reactions.

Compound reactions

In compound reactions, at least two elements form one product:

2Na (t) + Cl 2 (g) → 2NaCl (t)- formation of table salt.

Attention should be paid to an essential nuance of compound reactions: depending on the conditions of the reaction or the proportions of the reagents entering the reaction, its result may be different products. For example, under normal combustion conditions of coal, carbon dioxide is produced:
C (t) + O 2 (g) → CO 2 (g)

If the amount of oxygen is insufficient, then deadly carbon monoxide is formed:
2C (t) + O 2 (g) → 2CO (g)

Decomposition reactions

These reactions are, as it were, essentially opposite to the reactions of the compound. As a result of the decomposition reaction, the substance breaks down into two (3, 4...) simpler elements (compounds):

• 2H 2 O (l) → 2H 2 (g) + O 2 (g)- water decomposition
• 2H 2 O 2 (l) → 2H 2 (g) O + O 2 (g)- decomposition of hydrogen peroxide

Single displacement reactions

As a result of single substitution reactions, a more active element replaces a less active one in a compound:

Zn (s) + CuSO 4 (solution) → ZnSO 4 (solution) + Cu (s)

Zinc in a copper sulfate solution displaces the less active copper, resulting in the formation of a zinc sulfate solution.

The degree of activity of metals in increasing order of activity:

• The most active are alkali and alkaline earth metals

The ionic equation for the above reaction will be:

Zn (t) + Cu 2+ + SO 4 2- → Zn 2+ + SO 4 2- + Cu (t)

The ionic bond CuSO 4, when dissolved in water, breaks down into a copper cation (charge 2+) and a sulfate anion (charge 2-). As a result of the substitution reaction, a zinc cation is formed (which has the same charge as the copper cation: 2-). Please note that the sulfate anion is present on both sides of the equation, i.e., according to all the rules of mathematics, it can be reduced. The result is an ion-molecular equation:

Zn (t) + Cu 2+ → Zn 2+ + Cu (t)

Double displacement reactions

In double substitution reactions, two electrons are already replaced. Such reactions are also called exchange reactions. Such reactions take place in solution with the formation of:

• insoluble solid (precipitation reaction);
• water (neutralization reaction).

Precipitation reactions

When a solution of silver nitrate (salt) is mixed with a solution of sodium chloride, silver chloride is formed:

Molecular equation: KCl (solution) + AgNO 3 (p-p) → AgCl (s) + KNO 3 (p-p)

Ionic equation: K + + Cl - + Ag + + NO 3 - → AgCl (t) + K + + NO 3 -

Molecular ionic equation: Cl - + Ag + → AgCl (s)

If a compound is soluble, it will be present in solution in ionic form. If the compound is insoluble, it will precipitate to form a solid.

Neutralization reactions

These are reactions between acids and bases that result in the formation of water molecules.

For example, the reaction of mixing a solution of sulfuric acid and a solution of sodium hydroxide (lye):

Molecular equation: H 2 SO 4 (p-p) + 2NaOH (p-p) → Na 2 SO 4 (p-p) + 2H 2 O (l)

Ionic equation: 2H + + SO 4 2- + 2Na + + 2OH - → 2Na + + SO 4 2- + 2H 2 O (l)

Molecular ionic equation: 2H + + 2OH - → 2H 2 O (l) or H + + OH - → H 2 O (l)

Oxidation reactions

These are reactions of interaction of substances with gaseous oxygen in the air, during which, as a rule, a large amount of energy is released in the form of heat and light. A typical oxidation reaction is combustion. At the very beginning of this page is the reaction between methane and oxygen:

CH 4 (g) + 2O 2 (g) → CO 2 (g) + 2H 2 O (g)

Methane belongs to hydrocarbons (compounds of carbon and hydrogen). When a hydrocarbon reacts with oxygen, a lot of thermal energy is released.

Redox reactions

These are reactions in which electrons are exchanged between reactant atoms. The reactions discussed above are also redox reactions:

• 2Na + Cl 2 → 2NaCl - compound reaction
• CH 4 + 2O 2 → CO 2 + 2H 2 O - oxidation reaction
• Zn + CuSO 4 → ZnSO 4 + Cu - single substitution reaction

Redox reactions with a large number of examples of solving equations using the electron balance method and the half-reaction method are described in as much detail as possible in the section