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The main topics for gia in chemistry. Chemistry. A new complete guide to preparing for the OGE. Medvedev Yu.N

Chemistry. A new complete guide to preparing for the OGE. Medvedev Yu.N.

M.: 2017. - 320 p.

The new handbook contains all the theoretical material on the course of chemistry required to pass the main state exam in the 9th grade. It includes all elements of the content, checked by control and measuring materials, and helps to generalize and systematize knowledge and skills for the course of the secondary (complete) school. The theoretical material is presented in a concise and accessible form. Each topic is accompanied by examples of test tasks. Practical tasks correspond to the OGE format. Answers to the tests are given at the end of the manual. The manual is addressed to schoolchildren and teachers.

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CONTENT
From author 10
1.1. The structure of the atom. The structure of the electron shells of atoms of the first 20 elements of the Periodic Table D.I. Mendeleeva 12
The nucleus of an atom. Nucleons. Isotopes 12
Electronic shells 15
Electronic configurations of atoms 20
Tasks 27
1.2. Periodic law and Periodic system of chemical elements D.I. Mendeleev.
The physical meaning of the serial number of the chemical element 33
1.2.1. Groups and periods of the Periodic system 35
1.2.2. Patterns of changes in the properties of elements and their compounds in connection with the position in the Periodic system of chemical elements 37
Changing the properties of elements in the main subgroups. 37
Changing element properties by period 39
Tasks 44
1.3. The structure of molecules. Chemical bond: covalent (polar and non-polar), ionic, metallic 52
Covalent bond 52
Ionic bond 57
Metal connection 59
Tasks 60
1.4. Valency of chemical elements.
The degree of oxidation of chemical elements 63
Tasks 71
1.5. Pure substances and mixtures 74
Tasks 81
1.6. Simple and complex substances.
The main classes of inorganic substances.
Nomenclature of inorganic compounds 85
Oxides 87
Hydroxides 90
Acids 92
Salts 95
Tasks 97
2.1. Chemical reactions. Conditions and signs of chemical reactions. Chemical
equations. Conservation of the mass of substances in chemical reactions 101
Tasks 104
2.2. Classification of chemical reactions
on various grounds: the number and composition of the starting and obtained substances, changes in the oxidation states of chemical elements,
absorption and release of energy 107
Classification according to the number and composition of reagents and final substances 107
Classification of reactions according to the change in the oxidation states of chemical elements HO
Classification of reactions according to the thermal effect 111
Tasks 112
2.3. Electrolytes and non-electrolytes.
Cations and anions 116
2.4. Electrolytic dissociation of acids, alkalis and salts (medium) 116
Electrolytic dissociation of acids 119
Electrolytic dissociation of bases 119
Electrolytic dissociation of salts 120
Electrolytic dissociation of amphoteric hydroxides 121
Tasks 122
2.5. Ion exchange reactions and conditions for their implementation 125
Examples of writing reduced ionic equations 125
Conditions for the implementation of ion exchange reactions 127
Tasks 128
2.6. Redox reactions.
Oxidizing and reducing agents 133
Classification of redox reactions 134
Typical reducing and oxidizing agents 135
Selection of coefficients in the equations of redox reactions 136
Tasks 138
3.1. Chemical properties simple substances 143
3.1.1. Chemical properties of simple substances - metals: alkali and alkaline earth metals, aluminum, iron 143
Alkali metals 143
Alkaline earth metals 145
Aluminum 147
Iron 149
Tasks 152
3.1.2. Chemical properties of simple substances - non-metals: hydrogen, oxygen, halogens, sulfur, nitrogen, phosphorus,
carbon, silicon 158
Hydrogen 158
Oxygen 160
Halogens 162
Sulfur 167
Nitrogen 169
Phosphorus 170
Carbon and silicon 172
Tasks 175
3.2. Chemical properties of complex substances 178
3.2.1. Chemical properties of oxides: basic, amphoteric, acidic 178
Basic oxides 178
Acid oxides 179
Amphoteric oxides 180
Tasks 181
3.2.2. Chemical properties of bases 187
Tasks 189
3.2.3. Chemical properties of acids 193
General properties of acids 194
Specific properties of sulfuric acid 196
Specific properties of nitric acid 197
Specific properties of phosphoric acid 198
Tasks 199
3.2.4. Chemical properties of salts (medium) 204
Tasks 209
3.3. Relationship various classes inorganic substances 212
Tasks 214
3.4. Initial information about organic substances 219
Main classes of organic compounds 221
Fundamentals of the theory of the structure of organic compounds ... 223
3.4.1. Limit and unsaturated hydrocarbons: methane, ethane, ethylene, acetylene 226
Methane and ethane 226
Ethylene and acetylene 229
Tasks 232
3.4.2. Oxygen-containing substances: alcohols (methanol, ethanol, glycerin), carboxylic acids (acetic and stearic) 234
Alcohols 234
Carboxylic acids 237
Tasks 239
4.1. Rules for safe work in the school laboratory 242
Rules for safe work in the school laboratory. 242
Laboratory glassware and equipment 245
Separation of mixtures and purification of substances 248
Preparation of solutions 250
Tasks 253
4.2. Determination of the nature of the environment of solutions of acids and alkalis using indicators.
Qualitative reactions to ions in solution (chloride, sulfate, carbonate ions) 257
Determination of the nature of the environment of solutions of acids and alkalis using indicators 257
Qualitative reactions to ions
in solution 262
Tasks 263
4.3. Qualitative reactions to gaseous substances (oxygen, hydrogen, carbon dioxide, ammonia).

Obtaining gaseous substances 268
Qualitative reactions to gaseous substances 273
Tasks 274
4.4. Carrying out calculations based on formulas and equations of reactions 276
4.4.1. Calculation of the mass fraction of a chemical element in a substance 276
Tasks 277
4.4.2. Calculating the mass fraction of a solute in a solution 279
Tasks 280
4.4.3. Calculation of the amount of a substance, mass or volume of a substance from the amount of a substance, mass or volume of one of the reagents
or reaction products 281
Calculating the amount of a substance 282
Mass calculation 286
Volume calculation 288
Tasks 293
Information about the two exam models of the OGE in chemistry 296
Instructions for the implementation of the experimental task 296
Samples of experimental tasks 298
Answers to tasks 301
Applications 310
Table of solubility of inorganic substances in water 310
Electronegativity of s- and p-elements 311
Electrochemical voltage series of metals 311
Some of the most important physical constants 312
Prefixes in the formation of multiple and submultiple units 312
Electronic configurations of atoms 313
The most important acid-base indicators 318
Geometric structure of inorganic particles 319

The state final certification of 2019 in chemistry for graduates of the 9th grade of general educational institutions is carried out in order to assess the level of general education of graduates in this discipline. The tasks test knowledge of the following sections of chemistry:

The structure of the atom.
Periodic law and Periodic system of chemical elements D.I. Mendeleev.
The structure of molecules. Chemical bond: covalent (polar and non-polar), ionic, metallic.
Valency of chemical elements. The degree of oxidation of chemical elements.
Simple and complex substances.
Chemical reaction. Conditions and signs of chemical reactions. Chemical equations.
Electrolytes and non-electrolytes. Cations and anions. Electrolytic dissociation of acids, alkalis and salts (medium).
Ion exchange reactions and conditions for their implementation.
Chemical properties of simple substances: metals and non-metals.
Chemical properties of oxides: basic, amphoteric, acidic.
Chemical properties of bases. Chemical properties of acids.
Chemical properties of salts (medium).
Pure substances and mixtures. Rules for safe work in the school laboratory. chemical pollution environment and its consequences.
The degree of oxidation of chemical elements. Oxidizing agent and reducing agent. Redox reactions.
Calculation of the mass fraction of a chemical element in a substance.
Periodic law D.I. Mendeleev.
Initial information about organic substances. Biologically important substances: proteins, fats, carbohydrates.
Determination of the nature of the medium of a solution of acids and alkalis using indicators. Qualitative reactions to ions in solution (chloride, sulfate, carbonation, ammonium ion). Qualitative reactions to gaseous substances (oxygen, hydrogen, carbon dioxide, ammonia).
Chemical properties of simple substances. Chemical properties of complex substances.

Date of passing the OGE in chemistry 2019:
June 4 (Tuesday).

Changes in structure and content examination work 2019 compared to 2018 are absent.

In this section you will find online tests that will help you prepare for passing the OGE(GIA) in chemistry. We wish you success!

The standard OGE test (GIA-9) of the 2019 format in chemistry consists of two parts. The first part contains 19 tasks with a short answer, the second part contains 3 tasks with a detailed answer. In this regard, only the first part (i.e., the first 19 tasks) is presented in this test. According to the current structure of the exam, among these tasks, only 15 answers are offered. However, for the convenience of passing the tests, the site administration decided to offer answers in all tasks. But for tasks in which answer options are not provided by the compilers of real control and measuring materials (KIMs), the number of answer options has been significantly increased in order to bring our test as close as possible to what you will have to face at the end of the school year.

The standard OGE test (GIA-9) of the 2018 format in chemistry consists of two parts. The first part contains 19 tasks with a short answer, the second part contains 3 tasks with a detailed answer. In this regard, only the first part (i.e., the first 19 tasks) is presented in this test. According to the current structure of the exam, among these tasks, only 15 answers are offered. However, for the convenience of passing the tests, the site administration decided to offer answers in all tasks. But for tasks in which answer options are not provided by the compilers of real control and measuring materials (KIMs), the number of answer options has been significantly increased in order to bring our test as close as possible to what you will have to face at the end of the school year.

The standard OGE test (GIA-9) of the 2017 format in chemistry consists of two parts. The first part contains 19 tasks with a short answer, the second part contains 3 tasks with a detailed answer. In this regard, only the first part (i.e., the first 19 tasks) is presented in this test. According to the current structure of the exam, among these tasks, only 15 answers are offered. However, for the convenience of passing the tests, the site administration decided to offer answers in all tasks. But for tasks in which answer options are not provided by the compilers of real control and measuring materials (KIMs), the number of answer options has been significantly increased in order to bring our test as close as possible to what you will have to face at the end of the school year.

The standard OGE test (GIA-9) of the 2016 format in chemistry consists of two parts. The first part contains 19 tasks with a short answer, the second part contains 3 tasks with a detailed answer. In this regard, only the first part (i.e., the first 19 tasks) is presented in this test. According to the current structure of the exam, among these tasks, only 15 answers are offered. However, for the convenience of passing the tests, the site administration decided to offer answers in all tasks. But for tasks in which answer options are not provided by the compilers of real control and measuring materials (KIMs), the number of answer options has been significantly increased in order to bring our test as close as possible to what you will have to face at the end of the school year.

The standard OGE test (GIA-9) of the 2015 format in chemistry consists of two parts. The first part contains 19 tasks with a short answer, the second part contains 3 tasks with a detailed answer. In this regard, only the first part (i.e., the first 19 tasks) is presented in this test. According to the current structure of the exam, among these tasks, only 15 answers are offered. However, for the convenience of passing the tests, the site administration decided to offer answers in all tasks. But for tasks in which answer options are not provided by the compilers of real control and measuring materials (KIMs), the number of answer options has been significantly increased in order to bring our test as close as possible to what you will have to face at the end of the school year.

When completing tasks A1-A19, select only one correct option.
When completing tasks B1-B3, select two correct options.

When completing tasks A1-A15, select only one correct option.

When completing tasks A1-A15, choose only one correct option.

For schoolchildren who plan to master a profession related to chemistry in the future, the OGE in this subject is very important. If you want to get the best score on the tests, start preparing immediately. The best number of points in the performance of the work is 34. The indicators of this exam can be used when sending to specialized classes in a secondary school. At the same time, the minimum limit of the indicator by points in this case is 23.

What are the options

The OGE in chemistry, as in previous years, includes theory and practice. With the help of theoretical tasks, they check how boys and girls know the basic formulas and definitions of organic and inorganic chemistry and how to apply them in practice. The second part, respectively, is aimed at testing the ability of schoolchildren to carry out reactions of the redox and ion-exchange types, to have an idea of the molar masses and volumes of substances.

Why testing is necessary

OGE 2019 in chemistry requires serious preparation, as the subject is quite complicated. Many have already forgotten the theory, perhaps they misunderstood it, and without it it is impossible to correctly solve the practical part of the task.

It is worth taking the time to train now in order to show a decent result in the future. Today, schoolchildren have an excellent opportunity to assess their strength by solving last year's real tests. No costs - you can use school knowledge for free and understand how the exam will take place. Students will be able not only to repeat the material covered and complete the practical part, but also to feel the atmosphere of real tests.

Convenient and efficient

A great opportunity is to prepare for the OGE right at the computer. You just need to press the start button and start passing the tests online. This is very effective and can replace tutoring. For convenience, all tasks are grouped by ticket numbers and fully correspond to the real ones, since they are taken from the website of the Federal Institute of Pedagogical Measurements.

If you are not confident in your abilities, you are afraid of the upcoming tests, you have gaps in theory, you have not completed enough experimental tasks, turn on the computer and start preparing. We wish you success and the highest marks!

Task 1. The structure of the atom. The structure of the electron shells of atoms of the first 20 elements of the periodic system of DIMendeleev.

Task 2. Periodic law and periodic system of chemical elements D.I. Mendeleev.

Task 3.The structure of molecules. Chemical bond: covalent (polar and non-polar), ionic, metallic.

Task 4.

Task 5. Simple and complex substances. The main classes of inorganic substances. Nomenclature of inorganic compounds.

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Exercise 1

The structure of the atom. The structure of the electron shells of atoms of the first 20 elements of the periodic system of DIMendeleev.

How to determine the number of electrons, protons and neutrons in an atom?

The number of electrons is equal to the serial number and the number of protons.
The number of neutrons is equal to the difference between the mass number and the serial number.

The physical meaning of the serial number, period number and group number.

The serial number is equal to the number of protons and electrons, the charge of the nucleus.
The A-group number is equal to the number of electrons on the outer layer (valence electrons).

The maximum number of electrons in the levels.

The maximum number of electrons in the levels is determined by the formula N= 2 n 2 .

Level 1 - 2 electrons, Level 2 - 8, Level 3 - 18, Level 4 - 32 electrons.

Features of the filling of electron shells in elements A and B groups.

For elements of A - groups, valence (external) electrons fill the last layer, and for elements of B - groups - the outer electronic layer and partially the front outer layer.

Oxidation states of elements in higher oxides and volatile hydrogen compounds.

Groups							VIII
S.O. in higher oxide = + No. gr
Supreme Oxide	R 2 O	R 2 O 3	RO 2	R 2 O 5	RO 3	R 2 O 7	RO 4
S.O. in LAN = No. gr - 8
LAN			H 4 R	H 3 R	H 2 R

The structure of the electron shells of ions.

Cations have fewer electrons per charge, anions have more electrons per charge.

For example:

Ca 0 - 20 electrons, Ca2+ - 18 electrons;

S0 – 16 electrons, S 2- - 18 electrons.

Isotopes.

Isotopes are varieties of atoms of the same chemical element that have the same number of electrons and protons, but different atomic masses (different numbers of neutrons).

For example:

Elementary particles	isotopes
Elementary particles	40 Ca	42 Ca

Be sure to be able to according to the table D.I. Mendeleev to determine the structure of the electron shells of atoms of the first 20 elements.

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A 2. B 1.

Periodic law and periodic system of chemical elements D.I. Mendeleev

Patterns of changes in the chemical properties of elements and their compounds in connection with the position in the periodic system of chemical elements.

The physical meaning of the serial number, period number and group number.

The atomic (serial) number of a chemical element is equal to the number of protons and electrons, the charge of the nucleus.

The period number is equal to the number of filled electron layers.

The group number (A) is equal to the number of electrons in the outer layer (valence electrons).

Forms of existence chemical element and their properties		Property changes
Forms of existence chemical element and their properties		In the main subgroups (top to bottom)	In periods (from left to right)
atoms	Core charge	is increasing	is increasing
	Number of energy levels	is increasing	Does not change = period number
	Number of electrons in the outer level	Does not change = period number	is increasing
	Atom radius	Are increasing	Decreases
	Restorative properties	Are increasing	Decrease
	Oxidizing properties	Decreases	Are increasing
	Highest positive oxidation state	Constant = group number	Increases from +1 to +7 (+8)
	Lowest oxidation state	Doesn't change = (8-group number)	Increases from -4 to -1
Simple substances	Metal properties	is increasing	Decrease
Simple substances	Non-metallic properties	Decrease	is increasing
Element connections	The nature of the chemical properties of the higher oxide and higher hydroxide	Strengthening basic properties and weakening acidic properties	Strengthening acidic properties and weakening basic properties

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A 4

The degree of oxidation and valence of chemical elements.

Oxidation state- the conditional charge of an atom in a compound, calculated on the assumption that all bonds in this compound are ionic (i.e., all bonding electron pairs are completely shifted to an atom of a more electronegative element).

Rules for determining the oxidation state of an element in a compound:

S.O. free atoms and simple substances is equal to zero.
The sum of the oxidation states of all atoms in a complex substance is zero.
Metals have only positive S.O.
S.O. alkali metal atoms (I (A) group) +1.
S.O. atoms of alkaline earth metals (II (A) group) + 2.
S.O. atoms of boron, aluminum +3.
S.O. hydrogen atoms +1 (in hydrides of alkali and alkaline earth metals -1).
S.O. oxygen atoms -2 (exceptions: in peroxides -1, in OF 2 +2 ).
S.O. fluorine atoms are always - 1.
The oxidation state of a monatomic ion coincides with the charge of the ion.
Higher (maximum, positive) S.O. element is equal to the group number. This rule does not apply to elements of the secondary subgroup of the first group, the oxidation states of which usually exceed +1, as well as to the elements of the secondary subgroup of group VIII. Also, the elements oxygen and fluorine do not show their higher oxidation states, equal to the group number.
The lowest (minimum, negative) S.O. for non-metal elements is determined by the formula: group number -8.

* S.O. – degree of oxidation

Atom valenceis the ability of an atom to form a certain number of chemical bonds with other atoms. Valency has no sign.

Valence electrons are located on the outer layer of the elements of the A - groups, on the outer layer and d - the sublevel of the penultimate layer of the elements of the B - groups.

Valencies of some elements (denoted by Roman numerals).

permanent		variables
HE	valence	HE	valence
H, Na, K, Ag, F		Cl, Br, I	I (III, V, VII)
Be, Mg, Ca, Ba, O, Zn		Cu, Hg	II, I
Al, V			II, III
			II, IV, VI
			II, IV, VII
			III, VI
			I-V
			III, V
		C, Si	IV(II)

Examples of determining valency and S.O. atoms in compounds:

Formula	Valence	S.O.	Structural formula of a substance
	NIII		N N
NF3	N III, F I	N+3, F-1	F-N-F
NH3	N III, N I	N -3, N +1	H - N - H
H2O2	H I, O II	H +1, O -1	H-O-O-H
OF 2	O II, F I	O +2, F -1	F-O-F
*CO	C III, O III	C +2, O -2	The "C" atom donated two electrons for common use, and the more electronegative "O" atom pulled two electrons towards itself: “C” will not have the treasured eight electrons on the outer level – four of its own and two common with the oxygen atom. The atom "O" will have to transfer one of its free electron pairs for general use, i.e. act as a donor. The "C" atom will be the acceptor.

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A3. The structure of molecules. Chemical bond: covalent (polar and non-polar), ionic, metallic.

Chemical bonding is the force of interaction between atoms or groups of atoms, leading to the formation of molecules, ions, free radicals, as well as ionic, atomic and metallic crystal lattices.

covalent bondA bond is formed between atoms with the same electronegativity or between atoms with a small difference in electronegativity values.

A covalent non-polar bond is formed between atoms of the same elements - non-metals. A covalent non-polar bond is formed if the substance is simple, for example, O 2 , H 2 , N 2 .

A covalent polar bond is formed between atoms of different elements - non-metals.

A covalent polar bond is formed if the substance is complex, for example, SO 3, H 2 O, Hcl, NH 3.

The covalent bond is classified according to the mechanisms of formation:

exchange mechanism (due to common electron pairs);

donor-acceptor (an atom - a donor has a free electron pair and transfers it to common use with another atom - an acceptor, which has a free orbital). Examples: ammonium ion NH 4 + , carbon monoxide CO.

Ionic bond formed between atoms with very different electronegativity. As a rule, when atoms of metals and non-metals are connected. This is a connection between oppositely infected ions.

The greater the difference between the EOs of atoms, the more ionic the bond.

Examples: oxides, alkali and alkaline earth metal halides, all salts (including ammonium salts), all alkalis.

Rules for determining electronegativity according to the periodic table:

1) from left to right in the period and from bottom to top in the group, the electronegativity of atoms increases;

2) the most electronegative element is fluorine, since inert gases have a complete external level and do not tend to donate or accept electrons;

3) non-metal atoms are always more electronegative than metal atoms;

4) hydrogen has a low electronegativity, although it is located at the top of the periodic table.

metal connection- is formed between metal atoms due to free electrons holding positively charged ions in the crystal lattice. It is the bond between positively charged metal ions and electrons.

Substances of molecular structurehave a molecular crystal lattice,non-molecular structure- atomic, ionic or metallic crystal lattice.

Types of crystal lattices:

1) atomic crystal lattice: it is formed in substances with a covalent polar and non-polar bond (C, S, Si), atoms are located at the lattice nodes, these substances are the hardest and most refractory in nature;

2) molecular crystal lattice: formed in substances with covalent polar and covalent non-polar bonds, molecules are located at the lattice nodes, these substances have low hardness, fusible and volatile;

3) ionic crystal lattice: it is formed in substances with an ionic bond, there are ions at the lattice nodes, these substances are solid, refractory, non-volatile, but to a lesser extent than substances with an atomic lattice;

4) metal crystal lattice: formed in substances with a metallic bond, these substances have thermal conductivity, electrical conductivity, malleability and metallic luster.

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A5. Simple and complex substances. The main classes of inorganic substances. Nomenclature of inorganic compounds.

Simple and complex substances.

Simple substances are formed by atoms of one chemical element (hydrogen H 2, nitrogen N 2 , iron Fe, etc.), complex substances - atoms of two or more chemical elements (water H 2 O - consists of two elements (hydrogen, oxygen), sulfuric acid H 2 SO 4 - formed by atoms of three chemical elements (hydrogen, sulfur, oxygen)).

Main classes of inorganic substances, nomenclature.

oxides - complex substances consisting of two elements, one of which is oxygen in the oxidation state -2.

Nomenclature of oxides

The names of oxides consist of the words "oxide" and the name of the element in the genitive case (indicating the degree of oxidation of the element in Roman numerals in brackets): CuO - copper (II) oxide, N 2 O 5 - nitric oxide (V).

Character of oxides:

basic

amphoteric

non-salt-forming

acid

metal

S.O.+1,+2

S.O.+2, +3, +4

amp. Me - Be, Al, Zn, Cr, Fe, Mn

S.O.+5, +6, +7

non-metal

S.O.+1,+2

(excl. Cl 2 O)

S.O.+4,+5,+6,+7

Basic oxides form typical metals with C.O. +1, +2 (Li 2 O, MgO, CaO, CuO, etc.). Basic oxides are called oxides, which correspond to bases.

Acid oxidesform non-metals with S.O. more than +2 and metals with S.O. +5 to +7 (SO 2, SeO 2, P 2 O 5, As 2 O 3, CO 2, SiO 2, CrO 3 and Mn 2 O 7 ). Acidic oxides are called oxides, which correspond to acids.

Amphoteric oxidesformed by amphoteric metals with S.O. +2, +3, +4 (BeO, Cr 2 O 3 , ZnO, Al 2 O 3 , GeO 2 , SnO 2 and RIO). Amphoteric are oxides that exhibit chemical duality.

Non-salt-forming oxides– non-metal oxides with С.О.+1,+2 (СО, NO, N 2O, SiO).

Grounds ( basic hydroxides) - Compounds that are made up of

A metal ion (or ammonium ion) and a hydroxo group (-OH).

Base nomenclature

After the word "hydroxide" indicate the element and its oxidation state (if the element exhibits a constant oxidation state, then it can be omitted):

KOH - potassium hydroxide

Cr(OH) 2 – chromium (II) hydroxide

The grounds are classified:

1) according to their solubility in water, bases are divided into soluble (alkali and NH 4 OH) and insoluble (all other bases);

2) according to the degree of dissociation, the bases are divided into strong (alkali) and weak (all others).

3) by acidity, i.e. according to the number of hydroxo groups that can be replaced by acid residues: single acid (NaOH), two acid, three acid.

Acid hydroxides (acids)- complex substances that consist of hydrogen atoms and an acid residue.

Acids are classified:

a) according to the content of oxygen atoms in the molecule - into oxygen-free (Н C l) and oxygenated (H 2SO4);

b) by basicity, i.e. the number of hydrogen atoms that can be replaced by a metal - monobasic (HCN), dibasic (H 2 S), etc.;

c) by electrolytic strength - into strong and weak. The most commonly used strong acids are dilute aqueous solutions of HCl, HBr, HI, HNO 3 , H 2 S, HClO 4 .

Amphoteric hydroxidesformed by elements with amphoteric properties.

salt - complex substances formed by metal atoms combined with acidic residues.

Medium (normal) salts- iron(III) sulfide.

Acid salts - hydrogen atoms in the acid are partially replaced by metal atoms. They are obtained by neutralizing a base with an excess of an acid. To properly name acid salt, it is necessary to add the prefix hydro- or dihydro- to the name of the normal salt, depending on the number of hydrogen atoms that make up the acid salt.

For example, KHCO 3 – potassium bicarbonate, KH 2PO4 – potassium dihydrogen phosphate

It must be remembered that acid salts can form two or more basic acids, both oxygen-containing and anoxic acids.

Basic salts - hydroxo groups of the base (OH− ) are partially replaced by acid residues. To name basic salt, it is necessary to add the prefix hydroxo- or dihydroxo- to the name of the normal salt, depending on the number of OH - groups that make up the salt.

For example, (CuOH) 2 CO 3 - hydroxocarbonate of copper (II).

It must be remembered that basic salts are capable of forming only bases containing two or more hydroxo groups in their composition.

double salts - in their composition there are two different cations, they are obtained by crystallization from a mixed solution of salts with different cations, but the same anions.

mixed salts - in their composition there are two different anions.

Hydrate salts ( crystalline hydrates ) - they include molecules of crystallizationwater . Example: Na 2 SO 4 10H 2 O.

Who are these tests for?

These materials are intended for students preparing for OGE-2018 in chemistry. They can also be used for self-control when studying a school chemistry course. Each is dedicated to a specific topic that a ninth grader will meet on the exam. The test number is the number of the corresponding task in the OGE form.

How are thematic tests arranged?

Will other thematic tests be published on this site?

Undoubtedly! I plan to place tests on 23 topics, 10 tasks each. Stay tuned!

Thematic test number 11. Chemical properties of acids and bases. (Preparing for release!)

Thematic test number 12. Chemical properties of medium salts. (Preparing for release!)

Thematic test No. 13. Separation of mixtures and purification of substances. (Preparing for release!)

Thematic test number 14. Oxidizing agents and reducing agents. Redox reactions. (Preparing for release!)

What else is on this site for those preparing for the OGE-2018 in chemistry?

Do you feel like something is missing? Would you like to expand some sections? Need some new content? Something needs to be corrected? Did you find any mistakes?

Good luck to everyone preparing for the OGE and the USE!