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How to understand chemistry from scratch in a day. How to learn chemistry on your own from scratch: effective ways




Chemistry is considered one of the most complex and difficult subjects. Moreover, difficulties arise in the development of this subject for both schoolchildren and students. Why? Schoolchildren expect magic tricks, interesting experiments and demonstrations from the lesson. But already after the first lessons they are disappointed: there is not much laboratory work with reagents, basically you have to learn new terminology, do voluminous homework. Chemical language is completely different from everyday language, so you need to learn terms and names at an accelerated pace. In addition, you need to be able to think logically and apply mathematical knowledge.

Is it possible to learn chemistry on your own?

There is nothing impossible. Despite the complexity of science, chemistry can be learned from scratch. In some cases, when the topic is particularly complex or requires additional knowledge, you can use the services of an online tutor. The most convenient way to study is with the help of chemistry tutors via Skype. Distance learning allows you to study a particular topic in detail or clarify difficult points. You can contact a qualified teacher via Skype at any time.

In order for the learning process to be effective, several factors are needed:

  • Motivation. In any business, you need a goal to strive for. It doesn't matter what chemistry is studied for - for admission to medical school or the Faculty of Biology, just for self-development. The main thing is to set a goal and determine how to achieve it. Motivation will be the main driving factor that will force you to continue self-study.
  • Importance of details. It is simply impossible to learn a large amount of information in a short time. To learn chemistry effectively and be able to use knowledge correctly, you need to pay attention to details: formulas, solve a large number of examples, problems. For high-quality assimilation of the material, the systematization of information is required: they independently study a new topic, in addition solve problems and examples, learn formulas, etc.
  • Check of knowledge . To consolidate the material covered, it is recommended to periodically do verification work. The ability to understand and logically analyze allows you to assimilate knowledge better than "cramming". Teachers recommend periodically doing tests and tests for yourself. It will not be superfluous to repeat the material covered. Self-help books and tutorials help you learn chemistry on your own.
  • Practice and more practice... It is not enough to have theoretical knowledge well, you need to be able to apply it in practice, while solving problems. Practical exercises help to identify weaknesses in knowledge and consolidate the material covered. In addition, analytical skills and the logical construction of a solution chain are developed. While solving examples and problems, you draw conclusions and systematize the knowledge gained. When the tasks become absolutely clear, you can proceed to the study of the next topic.
  • Teach yourself. Not sure about the full development of chemistry? Try to teach this subject to someone. During the explanation of the material, weaknesses in knowledge are revealed, a system is built. It is important to take your time, paying attention to details and practical points.

You can learn chemistry on your own from a zero level if you have strong motivation and time. If the material is complex, professional tutors will help to understand the intricacies of the topic. Whether it will be a face-to-face consultation or via Skype is up to you. It is not necessary to take a full course from a tutor; in some cases, you can take a lesson on a separate topic.

E.N.FRENKEL

Chemistry tutorial

A guide for those who do not know, but want to learn and understand chemistry

Part I. Elements of General Chemistry
(first level of difficulty)

I, Frenkel Evgenia Nikolaevna, Honored Worker of the Higher School of the Russian Federation, a graduate of the Faculty of Chemistry of Moscow State University in 1972, teaching experience of 34 years. In addition, I am the mother of three children and the grandmother of four grandchildren, the eldest of whom is a schoolboy.

I am concerned about the problem of school textbooks. The main trouble of many of them is the difficult language, which requires additional “translation” into a language that is understandable to the student for presenting educational material. High school students often turn to me with such a request: “Translate the text of the textbook so that it is understandable.” That's why I wrote the "Self-Tutorial in Chemistry", in which many complex issues are presented quite clearly and at the same time scientifically. On the basis of this "Tutorial", which was written in 1991, I developed the program and content of the preparatory courses. They have trained hundreds of students. Many of them started from scratch and in 40 lessons they understood the subject so much that they passed exams with "4" and "5". Therefore, in our city, my manuals-tutorials disperse like hot cakes.

Maybe others will benefit from my work?

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Foreword

Dear readers! The “Self-Tutorial in Chemistry” brought to your attention is not an ordinary textbook. It does not simply state some facts or describe the properties of substances. The Self-Teacher explains and teaches even if, unfortunately, you do not know and do not understand chemistry, and you cannot or are embarrassed to ask a teacher for clarification. In the form of a manuscript, this book has been used by schoolchildren since 1991, and there was not a single student who failed the chemistry exam both at school and at universities. And many of them did not know chemistry at all.

"Tutorial" is designed for independent work of the student. The main thing is to answer in the course of reading those questions that are found in the text. If you could not answer the question, then read the text more carefully again - all the answers are nearby. It is also desirable to perform all the exercises that occur in the course of explaining new material. Numerous learning algorithms that are practically not found in other textbooks will help with this. With their help, you will learn:

Compose chemical formulas by valency;

Compose equations of chemical reactions, place coefficients in them, including in the equations of redox processes;

Compose electronic formulas (including short electronic formulas) of atoms and determine the properties of the corresponding chemical elements;

Predict the properties of certain compounds and determine whether a given process is possible or not.

The manual has two levels of difficulty. Tutorial first level of difficulty consists of three parts.

I part. Elements of General Chemistry ( published).

II part. Elements of inorganic chemistry.

III part. Elements of organic chemistry.

Books second level of difficulty also three.

Theoretical Foundations of General Chemistry.

Theoretical foundations of inorganic chemistry.

Theoretical Foundations of Organic Chemistry.

Chapter 1. Basic concepts of chemistry.

Exercises for chapter 1.

Chapter 2. The most important classes of inorganic compounds.

2.1. Oxides.

2.2. Acids.

2.3. Foundations.

Exercises for chapter 2.

Chapter 3. Elementary information about the structure of the atom. Periodic law of D.I. Mendeleev.

Exercises for chapter 3.

Chapter 4. The concept of a chemical bond.

Chapter 5. Solutions.

Chapter 6

6.1. The concept of pH (hydrogen index).

6.2. Salt hydrolysis.

Exercises for chapter 6.

Chapter 7

Chapter 8. Calculations by chemical formulas and equations.

8.1. Basic calculation concepts.

8.2. Problems solved by standard formulas.

8.2.1. Tasks on the topic "Gas".

8.2.2. Tasks on the topic "Methods of expressing the concentration of solutions."

8.2.3. Tasks on the topic "Quantitative composition of matter".

8.3. Problems solved by reaction equations.

8.3.1. Registration of calculations according to the equations of reactions.

8.3.2. Tasks on the topic "Quantitative composition of solutions and mixtures".

8.3.3. Tasks to establish the formula of a substance.

8.4. Tasks for independent solution.

Application.

Chapter 1. Basic concepts of chemistry

What is chemistry? Where do we meet with chemical phenomena?

Chemistry is everywhere. Life itself is a countless variety of chemical reactions, thanks to which we breathe, see the blue sky, smell the amazing smell of flowers.

What does chemistry study?

Chemistry is the study of substances and the chemical processes in which these substances are involved.

What is a substance?

Substance is what the world around us and ourselves consist of.

What is a chemical process (phenomenon)?

To chemical phenomena include processes that change the composition or structure of the molecules that form a given substance*. The molecules have changed - the substance has changed (it has become different), its properties have changed. For example, fresh milk turned sour, green leaves turned yellow, raw meat changed its smell when roasted.

All these changes are the result of complex and diverse chemical processes. However, the signs of simple chemical reactions, as a result of which the composition and structure of molecules change, are the same: a change in color, taste or smell, the release of gas, light or heat, the appearance of a precipitate.

What are the molecules, the change of which entails such diverse manifestations?

Molecules are the smallest particles of a substance, reflecting its qualitative and quantitative composition and its chemical properties.

By studying the composition and structure of one molecule, one can predict many properties of a given substance as a whole. Such research is one of the main tasks of chemistry.

How are molecules arranged? What are they made of?

Molecules are made up of atoms. The atoms in a molecule are connected by chemical bonds. Each atom is labeled with symbol(chemical sign). For example, H is a hydrogen atom, O is an oxygen atom.

The number of atoms in a molecule is denoted by index - numbers at the bottom right after the symbol.

For example:

Molecule examples:

O 2 is an oxygen substance molecule consisting of two oxygen atoms;

H 2 O is a water molecule consisting of two hydrogen atoms and one oxygen atom.

If the atoms are not linked by a chemical bond, then their number is denoted by coefficient - digits before character:

Similarly, the number of molecules is depicted:

2H 2 - two molecules of hydrogen;

3H 2 O - three water molecules.

Why do hydrogen and oxygen atoms have different names and different symbols? Because they are atoms of different chemical elements.

An element is a type of atom with the same nuclear charge.

What is the nucleus of an atom? Why is the nuclear charge a sign that an atom belongs to a given chemical element? To answer these questions, it is necessary to clarify: do atoms change in chemical reactions, what does an atom consist of?

A neutral atom has no charge, although it consists of a positively charged nucleus and negatively charged electrons:

During chemical reactions the number of electrons in any atom can change, but the charge of the nucleus of an atom does not change. Therefore, the charge of the nucleus of an atom is a kind of "passport" of a chemical element. All atoms with a nuclear charge of +1 belong to the chemical element called hydrogen. Atoms with a nuclear charge of +8 belong to the chemical element oxygen.

Each chemical element is assigned a chemical symbol (sign), a serial number in the Mendeleev table (the serial number is equal to the charge of the atomic nucleus), a specific name, and for some chemical elements - a special reading of the symbol in the chemical formula (Table 1).

Table 1

Symbols (signs) of chemical elements

No. p / p No. in the table of D.I. Mendeleev Symbol Reading in formula Name
1 1 H ash Hydrogen
2 6 C tse Carbon
3 7 N en Nitrogen
4 8 O about Oxygen
5 9 F fluorine Fluorine
6 11 Na sodium Sodium
7 12 mg magnesium Magnesium
8 13 Al aluminum Aluminum
9 14 Si silicium Silicon
10 15 P pe Phosphorus
11 16 S es Sulfur
12 17 Cl chlorine Chlorine
13 19 K potassium Potassium
14 20 Ca calcium Calcium
15 23 V vanadium Vanadium
16 24 Cr chromium Chromium
17 25 Mn manganese Manganese
18 26 Fe ferrum Iron
19 29 Cu cuprum Copper
20 30 Zn zinc Zinc
21 35 Br bromine Bromine
22 47 Ag argentum Silver
23 50 sn stannum Tin
24 53 I iodine Iodine
25 56 Ba barium Barium
26 79 Au aurum Gold
27 80 hg hydrargyrum Mercury
28 82 Pb plumbum lead

Substances are simple and complex . If a molecule is made up of atoms of one chemical element, it is simple substance. Simple substances - Ca, Cl 2, O 3, S 8, etc.

molecules complex substances are made up of atoms of different chemical elements. Complex substances - H 2 O, NO, H 3 PO 4, C 12 H 22 O 11, etc.

Task 1.1. Indicate the number of atoms in the molecules of complex substances H 2 O, NO, H 3 PO 4, C 12 H 22 O 11, name these atoms.

The question arises: why is the formula H 2 O always written for water, and not HO or HO 2? Experience proves that the composition of water obtained by any method or taken from any source always corresponds to the formula H 2 O (we are talking about pure water).

The fact is that the atoms in the molecule of water and in the molecule of any other substance are connected by chemical bonds. A chemical bond connects at least two atoms. Therefore, if a molecule consists of two atoms and one of them forms three chemical bonds, then the other also forms three chemical bonds.

Number of chemical bonds formed by an atom is called valence.

If we denote each chemical bond with a dash, then for a molecule of two atoms AB we get AB, where three dashes show three bonds formed by elements A and B between themselves.

In this molecule, atoms A and B are trivalent.

It is known that the oxygen atom is bivalent, the hydrogen atom is monovalent.

Question. How many hydrogen atoms can attach to one oxygen atom?

Answer: Two atoms. The composition of water is described by the formula H–O–H, or H 2 O.

Remember! In a stable molecule there can be no "free", "extra" valences. Therefore, for a two-element molecule, the number of chemical bonds (valencies) of atoms of one element is equal to the total number of chemical bonds of atoms of another element.

Valence of atoms of some chemical elements constant(Table 2).

table 2

The value of constant valencies of some elements

For other atoms, valency ** can be determined (calculated) from the chemical formula of a substance. In this case, the above rule on chemical bonding must be taken into account. For example, let's define the valency x manganese Mn according to the formula of the substance MnO 2:

The total number of chemical bonds formed by one and the other element (Mn and O) is the same:
x 1 = 4; II 2 = 4. Hence X= 4, i.e. in this chemical formula, manganese is tetravalent.

P ractical conclusions

1. If one of the atoms in the molecule is monovalent, then the valency of the second atom is equal to the number of atoms of the first element (see the index!):

2. If the number of atoms in the molecule is the same, then the valency of the first atom is equal to the valency of the second atom:

3. If one of the atoms has no index, then its valency is equal to the product of the valence of the second atom by its index:

4. In other cases, put the valencies "crosswise", i.e. the valence of one element is equal to the index of another element:

Task 1.2. Determine the valency of the elements in the compounds:

CO 2 , CO, Mn 2 O 7 , Cl 2 O, P 2 O 3 , AlP, Na 2 S, NH 3 , Mg 3 N 2 .

Clue. First, indicate the valence of the atoms in which it is constant. Similarly, the valency of atomic groups OH, PO 4, SO 4, etc. is determined.

Task 1.3. Determine the valencies of atomic groups (underlined in the formulas):

H3 PO 4 , Ca( Oh) 2 , Ca 3 ( PO 4) 2 , H 2 SO 4, Cu SO 4 .

(Please note! The same groups of atoms have the same valencies in all compounds.)

Knowing the valences of an atom or a group of atoms, you can draw up a formula for a compound. To do this, use the following rules.

If the valences of the atoms are the same, then the number of atoms is the same, i.e. do not set indexes:

If the valences are multiples (both are divisible by the same number), then the number of atoms of an element with a lower valence is determined by dividing:

In other cases, the indices are determined "crosswise":

Task 1.4. Write the chemical formulas of the compounds:

Substances whose composition is reflected in chemical formulas can participate in chemical processes (reactions). The graphical notation corresponding to a given chemical reaction is called reaction equation. For example, during the combustion (interaction with oxygen) of coal, a chemical reaction occurs:

C + O 2 \u003d CO 2.

The record shows that one carbon atom C, combining with one molecule of oxygen O 2, forms one molecule of carbon dioxide CO 2. The number of atoms of each chemical element before and after the reaction must be the same. This rule is a consequence of the law of conservation of mass of matter. The law of conservation of mass: the mass of the starting materials is equal to the mass of the reaction products.

The law was discovered in the 18th century. M.V. Lomonosov and, independently of him, A.L. Lavoisier.

Fulfilling this law, it is necessary to arrange the coefficients in the equations of chemical reactions so that the number of atoms of each chemical element does not change as a result of the reaction. For example, when decomposing the Bertolet salt KClO 3, a KCl salt and oxygen O 2 are obtained:

KClO 3 KCl + O 2.

The number of potassium and chlorine atoms is the same, but oxygen is different. Let's equalize them:

Now the number of potassium and chlorine atoms has changed before the reaction. Let's equalize them:

Finally, between the right and left sides of the equation, you can put an equal sign:

2KClO 3 \u003d 2KCl + 3O 2.

The resulting record shows that when the complex substance KClO 3 is decomposed, two new substances are obtained - a complex KCl and a simple one - oxygen O 2. The numbers in front of the formulas of substances in the equations of chemical reactions are called coefficients.

When selecting coefficients, it is not necessary to count individual atoms. If the composition of some atomic groups did not change during the reaction, then the number of these groups can be taken into account, considering them as a single whole. Let's make an equation for the reaction of substances CaCl 2 and Na 3 PO 4:

CaCl 2 + Na 3 PO 4 ……………….

Sequencing

1) Determine the valency of the initial atoms and the PO 4 group:

2) Let's write the right side of the equation (so far without indices, the formulas of substances in brackets need to be clarified):

3) Let's compose the chemical formulas of the obtained substances according to the valencies of the constituent parts:

4) Let's pay attention to the composition of the most complex compound Ca 3 (PO 4) 2 and equalize the number of calcium atoms (there are three of them) and the number of PO 4 groups (there are two of them):

5) The number of sodium and chlorine atoms before the reaction is now six. We put the corresponding coefficient on the right side of the scheme in front of the NaCl formula:

3CaCl 2 + 2Na 3 PO 4 = Ca 3 (PO 4) 2 + 6NaCl.

Using this sequence, you can equate the schemes of many chemical reactions (with the exception of more complex redox reactions, see Chapter 7).

Types of chemical reactions. Chemical reactions are of different types. The main ones are four types - connection, decomposition, substitution and exchange.

1. Connection reactions- from two or more substances one substance is formed:

For example:

Ca + Cl 2 \u003d CaCl 2.

2. Decomposition reactions- two or more substances are obtained from one substance:

For example:

Ca(HCO 3) 2 CaCO 3 + CO 2 + H 2 O.

3. Substitution reactions- simple and complex substances react, simple and complex substances are also formed, and a simple substance replaces part of the atoms of a complex substance:

A + BX AX + B.

For example:

Fe + CuSO 4 \u003d Cu + FeSO 4.

4. Exchange reactions- here two complex substances react and two complex substances are obtained. In the course of the reaction, complex substances exchange their constituent parts:

Exercises for chapter 1

1. Learn the table. 1. Check yourself, write chemical symbols: sulfur, zinc, tin, magnesium, manganese, potassium, calcium, lead, iron and fluorine.

2. Write the symbols of chemical elements that are pronounced in the formulas as: “ash”, “o”, “kuprum”, “es”, “pe”, “hydrargyrum”, “stannum”, “plumbum”, “en”, “ferrum” , "tse", "argentum". Name these elements.

3. Indicate the number of atoms of each chemical element in the formulas of compounds:

Al 2 S 3, CaS, MnO 2, NH 3, Mg 3 P 2, SO 3.

4. Determine which of the substances are simple and which are complex:

Na 2 O, Na, O 2, CaCl 2, Cl 2.

Read the formulas for these substances.

5. Learn the table. 2. Compose the chemical formulas of substances according to the known valency of elements and atomic groups:

6. Determine the valency of chemical elements in compounds:

N 2 O, Fe 2 O 3, PbO 2, N 2 O 5, HBr, SiH 4, H 2 S, MnO, Al 2 S 3.

7. Arrange the coefficients and indicate the types of chemical reactions:

a) Mg + O 2 MgO;

b) Al + CuCl 2 AlCl 3 + Cu;

c) NaNO 3 NaNO 2 + O 2;

d) AgNO 3 + BaCl 2 AgCl + Ba(NO 3) 2;

e) Al + HCl AlCl 3 + H 2;

f) KOH + H 3 PO 4 K 3 PO 4 + H 2 O;

g) CH 4 C 2 H 2 + H 2.

* There are substances that are not built from molecules. But these substances will be discussed later (see Chapter 4).

** Strictly speaking, according to the rules below, it is not the valence that is determined, but the degree of oxidation (see Chapter 7). However, in many compounds, the numerical values ​​​​of these concepts coincide, therefore, valence can also be determined from the formula of a substance.

Printed with a continuation

Everything around us - on the street, on a robot, in public transport is related in chemistry. Yes, and we ourselves consist of a number of chemical elements and processes. Therefore, the question of how to teach chemistry is quite relevant.

This article is intended for persons over 18 years of age.

Are you over 18 already?

Chemistry Teaching Methods

Not a single branch of industry, agriculture can do without this miracle science. Modern technologies use all possible developments in order for progress to move on. Medicine and pharmacology, construction and light industry, cooking and our everyday life - they all depend on chemistry, its theory and research.

But not all young people at school age understand the need and importance of chemistry in our lives, do not attend classes, do not listen to teachers and do not delve into the essence of the processes. In order to interest and instill a love for science and the school curriculum among students in grades 8, 9, 10, teachers use different methods and educational technologies, specific methods and use research technologies.

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Is it easy to learn chemistry on your own?

It often happens that after completing a course in a certain subject in high school or college, the student realizes that he listened to it inattentively and did not understand anything. This may show up on his annual grade, or it may cost him a budget place at the university. Therefore, many negligent schoolchildren try to study chemistry on their own.

And here questions arise. Is it real? Is it possible to learn a difficult subject on your own? How to organize your time and where to start? Of course, it is possible and quite realistic, the main thing is perseverance and the desire to achieve your goal. Where to start? No matter how trite it may sound, but motivation plays a crucial role in the whole process. It depends on her whether you can sit over textbooks for a long time, learn formulas and tables, break down processes and do experiments.

When you have identified a goal for yourself, you need to start implementing it. If you are starting to learn chemistry from scratch, then you can stock up on textbooks for the 8th grade program, beginners' manuals and laboratory notebooks where you will write down the results of the experiments. But often there are situations when home teaching is not effective and does not bring the desired results. There can be many reasons: there is not enough perseverance, there is no willpower, some points are incomprehensible, without which further training does not make sense.

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Is it possible to learn chemistry quickly?

Many schoolchildren and students want to learn chemistry from scratch without much effort and in a short time, they are looking online for ways to learn a subject in 5 minutes, in 1 day, in a week or a month. It is impossible to say how much you can learn chemistry for. It all depends on the desire, motivation, abilities and capabilities of each individual student. And it is worth remembering that quickly learned information just as quickly disappears from our memory. Therefore, is it worth it to quickly learn the entire school chemistry course in a day? Or is it better to spend more time, but after that pass all the exams with excellent marks?

Regardless of how long you are going to learn chemistry, it is worth choosing convenient methods that will facilitate the already difficult task of learning the basics of organic and inorganic chemistry, the characteristics of chemical elements, formulas, acids, alkanes and much more.

The most popular method, which is used in secondary schools, preschool institutions, in courses for the study of a particular subject, is a game method. It allows you to memorize a large amount of information in a simple and accessible form without spending a lot of effort on it. You can buy a young chemist's kit (yes, don't be embarrassed) and in a simple way see many important processes and reactions, observe the interaction of different substances, and at the same time it is quite safe. In addition, use the method of cards or stickers that you place on different items (this is especially suitable for the kitchen) indicating the name of the chemical element, its properties, formula. Bumping into such pictures all over the house, you will remember the necessary data on a subconscious level.

Alternatively, you can buy a book for children, which describes the initial and main points in a simple form, or you can watch an educational video where chemical reactions are explained based on home experiments.

Do not forget to control yourself by doing tests and examples, solving problems - this is how you can consolidate knowledge. Well, repeat the material already learned before, the new one that you are now learning. It is the return back, the reminder, that makes it possible to keep all the information in your head and not forget it for the exam.

An important point is the help of your smartphone or tablet, on which you can install special educational programs in order to learn chemistry. These applications can be downloaded for free by selecting the desired level of knowledge - for beginners (if you teach from scratch), intermediate (high school course) or advanced (for students of biological and medical faculties). The advantage of such devices is that you can repeat or learn something new from anywhere and at any time.

And finally. In whatever field you may succeed in the future: science, economics, fine arts, agriculture, the military field or industry, remember that knowledge of chemistry will never be superfluous!

I. I want to learn how to findrelative molecular weight.

Wonderful! We start learning. suppose we need to find the relative molecular weight of sodium sulfate Na 2 SO 4 ,our actions:

1. Found in the Periodic system sodium (No. 11)
2. We saw the number 22.9 under the name and rounded up to 23.
3. Since there are two sodium atoms, we multiply 23 by 2 and get 46.
4. Found sulfur in the periodic system (No. 16)
5. We saw the number 32 under the name, we will not multiply, because one sulfur atom.
6. Found oxygen in the Periodic system (No. 8)
7. 15.9 is written under the name, we round it up, we get 16. There are 4 oxygen atoms in the molecule, so we need to multiply 16 by 4. We get 64.
8 Last action:
46+32+64=142 Hurrah! we have found the relative molecular weight of sodium sulfate.

Perhaps you should practice on your own.
Try to calculate for:

H2SO4 you should get 98

Ca(OH)2 you should get 74

K3PO4 you should get 212

If you made it, then congratulations. You have taken the first step towards problem solving.

As a reminder, molar mass is numerically equal to molecular mass, but is measured in grams/mol (g/mol).

II. I want to learn how to findthe number of moles of the substance.

You will need formulas:

n= m/M use if we are given a mass

n= v / V M we use if we are given a volume

n= N/ N A we use if we are given number of atoms or molecules.

Task: find the amount of sodium sulfate substance with a mass of 7.1 g.

Given: solution:
m (Na 2 SO 4) \u003d 7.1 g We are given a mass, which means we will use the formula with mass
_____________ n=m / M, where M - molar mass (if we do not know how to count it, see item I)

Find: n M ((Na 2 SO 4) \u003d 46 + 32 + 16 * 4 \u003d 142 g / mol

n= 7.1g / 142g/mol= 0.05 mol

Answer: n=0.05 mol

Try to find the amount of the substance yourself, if given
1. 196g H2SO4(answer 2 mol)
2.20.2g KNO 3 (answer 0.2 mol)
3. 16g NaOH (answer 0.4 mol)

We invite you to solve the following tasks yourself: Don't be afraid, you can handle it!)

1. Find the amount of substance that is 49 g of copper (II) hydroxide.
2. How many molecules contain 4.48 liters of hydrogen?
3. Find the mass of 5.6 liters of nitrogen.
4. What is the volume of oxide sulfurs (IV) with a mass of 80 g?

Show the solution of these problems to your chemistry teacher. Ask questions if something is not clear.

III. I want to learn how to solve problems with the calculation of the reaction equation.

Task: find the mass of magnesium oxide that can dissolve in 12.6 g of nitric acid.

Given:
m(HNO 3) \u003d 12.6g
___________
Find:m(MgO)

Solution: 1 . The first action of any such task is find the number of moles of a given substance .
for this we use the formula (see item 2). Since we are given the mass, our formula: n \u003d m / M
n(HNO 3)= 12.6g / M(HNO 3)=12.6 / (1+14+48) =12.6 / 63 = 0.2 mol

2. Second action - write down the reaction equation, arrange the coefficients.

3. Third act - write the number of moles , calculated in the first action, over the substance for which it is calculated, and over the desired one put X
X ,,,0.2 mol
MgO +2 HNO 3 \u003d Mg (NO 3) 2 + H 2 O

4. Under these substances write down the amount of substance needed according to the equation - the reaction coefficient:
x............0.2 mol
MgO+2 HNO 3 \u003d Mg (NO 3) 2 + H 2 O
1 mol 2 mol

5. Thus we have a record
x............0.2 mol
MgO +2 HNO 3 \u003d Mg (NO 3) 2 + H 2 O
1 mol 2 mol

In this entry we will see the proportion: x: 1 \u003d 0.2: 2, solve the equation(the product of the extreme terms of the proportion is equal to the product of the middle ones) x \u003d 0.1, that is, n (MgO )=0.1mol
5. We have found the amount of matter, and we are asked the mass. We use the formula: m=n*M
m( MgO )=0.1*(24+16) =4g

Answer: the mass of magnesium oxide is 4 g.

Try to solve the problem yourself :( Be careful and careful!)

1. Calculate the volume of sulfur oxide (IV), which is formed during the combustion of 80 g of sulfur.
2.Calculate the mass of aluminum oxide, which is formed when aluminum burns in 4.48 liters of oxygen .

3. Find the volume of oxygen required to burn 12g of magnesium.
4. Find the mass of zinc oxide, which is formed by the interaction of zinc with 11.2 liters of oxygen.
5. Find the mass of sodium oxide, which is formed when sodium reacts with 4.48 liters of oxygen.
6. Find the volume of carbon dioxide that is formed when 60 g of coal is burned.
7. Find the volume of oxygen consumed during the combustion of 3.1 g of phosphorus.
8. Find the mass of phosphorus that can burn in 4.48 liters of oxygen.
9. Find the volume of chlorine required to interact with 5.4 g of aluminum.
10.Find the volume of chlorine with which 4.6 g of sodium can react.
11. Find the mass of aluminum chloride, which is formed when 1.12 liters of chlorine react with aluminum.
12.Find the mass of iron (III) chloride, which is formed when 11.2 liters of chlorine react with iron.
13.How many liters of oxygen will be required to burn 6.2 g of phosphorus?
14. Find the mass of carbon monoxide (IV), which is formed during the combustion of coal in 8.96 liters of oxygen.

IV. I want to learn how to write down the scheme of the electronic configuration of an atom (electronic passport)

To do this, you need to remember that the s-orbital can have no more than 2 electrons, the p-orbital - no more than six, the d-orbital no more than 10, the f-orbital - no more than 14.
so:
S-2
P-6
d - 10
f-14
The orbitals are filled with electrons in the following order:
1s2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f5d 6p 7s 5f6d 7p

Note that the number of the d-orbital is always one less than the number of the s-orbital after which it is located.

The number of electrons in an atom is equal to the number of protons in its nucleus, equal to the element number in Periodic system.

So, suppose that we need to draw up a diagram of the electronic configuration of the potassium atom.
Its number is 19, which means there are 19 electrons in the atom.
We start in order with 1s, filling the orbitals with the maximum number of electrons possible for them and writing this number as a power over the symbol of the orbital:

1s 2 2s 2 2p 63s 2 3p 6 4s 1

There is one electron in the last orbital, because we need to "attach" a total of 19 electrons and writing 1s 2 2s 2 2p 6 3s 2 3p 6 we have just one electron left. It will be located on the next 4s orbital in order.
Let's check ourselves:
Potassium is in fourth period Consequently outer level fourth.
Potassium is in the first group, therefore it has one electron in its outer level.
We wrote the diagram correctly.

We need to practice.
Try to write electronic passports for atoms of chlorine, sodium, nitrogen, magnesium, oxygen. And then aim at tungsten, antimony, iodine, barium, etc. You will succeed, you just need to be careful and persistent.

Check yourself:

Cl 1s 2 2s 2 2p 6 3s 2 3p 5

Na 1s 2 2s 2 2p 6 3s 1

N 1s 2 2s 2 2p 3

Mg 1s 2 2s 2 2p 6 3s 2

O 1s 2 2s 2 2p 4
VI want to learn how to predict the properties of an element by its position in the Periodic Table.

The most energetically favorable state with a filled outer level (8 electrons). Elements have this configuration. neon, argon, krypton, xenon and radon. they are called inert (noble) gases, since they do not interact. They are located in the 8th group.
Other elements
or add electrons missing up to 8
e.g. Cl at outer level 7 electrons (write his passport) , missing 1 will attach 1 electron.
e.g. O at outer level 6 electrons (write his passport) , lacking 2, will attach 2 electrons.
electrons will be attached to elements that have 4-7 electrons at the external level. Such elements are called NON-METALS. The easier an element accepts electrons, the more active it is non-metal.
Look at the Periodic Table and explain why they exhibit non-metallic properties phosphorus, arsenic, selenium, bromine, nitrogen, fluorine, carbon.

or donate electrons from the outer level, as a result of which the filled previous level becomes outer.
for example, sodium has 1 electron in the outer level, and 8 in the previous one, (write his passport) so sodium donates 1 electron.
for example, aluminum has 3 electrons in the outer level, and 8 in the previous level ( write his passport) so aluminum donates 3 electrons.
Elements that have 1-3 electrons at the external level will give electrons. These are METALS. The easier an element gives off electoral electrons, the more active it is.
Find in the Periodic system magnesium, potassium, indium, rubidium, calcium and explain their properties.

The ability to take or donate electrons depends on distance between core and outer layer, which defines force of attraction of electrons of the outer level to the nucleus.
for example, nitrogen and bismuth are located in the V group, which means they have 5 electrons in the outer level and they both must be non-metals. But bismuth is a metal, since its outer level ( 6th, we recognized it by the period number) is located far from the nucleus, the attraction of electrons of the outer level to the nucleus is small and bismuth does not add electrons, but gives away , and therefore metal.
Compare the properties of carbon and tin, sulfur and polonium. Using "magic words" - distance and attraction- Explain your conclusion.

I want to learn to recognize the main classes of inorganic substances and to know their properties.

There are 4 main classes of substances:
oxides, acids, bases and salts.
You need to learn the definitions:

oxides - complex substances consisting of two elements, one of which is oxygen.
oxide - EhOy for example: Na 2 O - sodium oxide, CuO - copper (II) oxide, P 2 O 5 - phosphorus oxide

acids - complex substances consisting of hydrogen atoms and an acid residue.
acid - NxA, where A is the acid residue.
for example HCl - hydrochloric acid, H 2 SO 4 - sulfuric acid, HNO 3 - nitric acid

grounds - complex substances consisting of metal atoms and OH hydroxogroups.

base - Me (OH) x
for example: KOH - potassium hydroxide, Ca (OH) 2 - calcium hydroxide


salt - complex substances consisting of metal atoms and an acid residue.

salt- MechAy

for example: Na 2 SO 4 - sodium sulfate, Cu (NO 3) 2 - copper (II) nitrate.

Let's check how you understood the classification.
In each line, find the extra substance:

1. NaOH HCl Mg (OH) 2 Fe (OH) 3
2. HNO 3 H 2 SO 4 H 2 O HCl
3. Cl 2 O 7 MnO NaOH K 2 O
4. Ca (OH) 2 CuCl 2 Na 2 SO 3 Mn (NO 3) 2
5. CuSO 4 NaCl FeCO 3 H 3 PO 4

check your answers:
1. HCl is an acid, and all other substances are bases
2. H 2 O is an oxide, and all other substances are acids.
3. NaOH is a base, and all other substances are oxides.
4. Ca (OH) 2 is a base, and all other substances are salts.
5. H 3 PO 4 is an acid, and all other substances are salts.

Now it's time to deal with the chemical properties.

The properties of oxides depend on which element forms the oxide.
if the element is a metal, then in most cases it forms a basic oxide,
if the element is a non-metal, then its oxide is, in most cases, acidic.

basic oxide + water = alkali (soluble base) 1
+ acid = salt and water 2
+ acid oxide = salt 3

Remember this pattern! She will be very useful to us. How does this diagram help us write the reaction equations?
For example:
you need to complete the equation and place the coefficients:
CaO + HNO 3 =

Your actions:
1. Find out what kind of substances react:
CaO - oxide, metal oxide, means basic oxide
HNO 3 - acid
2. determine property number
basic oxide + acid - property number 2, which means should be salt and water
3. What is salt? ( This is a complex substance consisting of metal atoms and an acid residue)
who is metal here? ( calcium)
Where is the acid residue? it is part of the acid, it is NO 3)
4. To correctly write down the salt formula, you need to take into account the valence (for calcium - II, for the acid residue - 1).

We write the equation:

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

5. Set the coefficients:

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

And now try to complete the reaction equations yourself and arrange the coefficients:
MgO+HCl=
Na 2 O + H 3 PO 4 \u003d
CuO + H 2 SO 4 \u003d
BaO + H 2 O =
Na 2 O + H 2 O \u003d
CaO + CO 2 \u003d
MgO + P 2 O 5 \u003d

If you want to check the result, show what you got to Alexandra Evgenievna. She will gladly check, explain the errors, and if there are none, she will put "5" in the log.

Let's now look at the properties of acidic oxides.

acid oxide + water = acid 4
+ lye = salt + water 5
+ basic oxide = salt 6

Suppose we need to complete the following equation and arrange the coefficients:
P 2 O 5 + H 2 O =
Our reasoning:
1. What class of substances does the first substance belong to? ( oxide, non-metal oxide, acid oxide).
2. Determine the property number
(acid oxide + water is property number 4, it should be acid.)
3. What is an acid? ( complex substance consisting of hydrogen atoms and an acid residue)
4. Write down the equation:
P 2 O 5 + H 2 O = H3PO4
We set the coefficients:
P 2 O 5 + 3H 2 O \u003d 2H3PO4

Now try it yourself:
CO 2 +H 2 O \u003d
SiO 2 + KOH =
P 2 O 5 + LiOH =
CO 2 + Ca (OH) 2 \u003d
SO 3 + MgO =

If you want to check your work, show it to Alexandra Evgenievna.

Consider the properties of acids.

acid + metal( standing in a series of voltages up to hydrogen) \u003d salt + H 2
+ metal oxide = salt + water
+ base = salt + water
+ salt = another salt + another acid ( this reaction should form a precipitate or evolve a gas)

Let's try to practice choosing substances that can react with acids.

What substance can hydrochloric acid react with?

Copper is in the series of voltages after hydrogen, therefore it does not react with hydrochloric acid solution.

Sulfur oxide is an acidic oxide, since sulfur is a non-metal. Acids do not react with acidic oxides.

You have made the right choice. Magnesium hydroxide is a base. Acids react with bases to form salt and water.

With non-metals, which is oxygen, acids do not interact.

Now we are working on our own.
In each line, find a substance that can interact with a solution of sulfuric acid.
Ag CuO HNO 3 NaCl
Mg(OH) 2 KCl Hg CO 2
P P 2 O 5 K 3 PO 4 K 2 O
Li 2 SO 4 LiCl LiNO 3 Li 2 CO 3

Answers: CuO. Mg(OH)2. K 2 O. Li 2 CO 3

REMEMBER:
All carbonates react with acids, as the result is unstable carbonic acid, which immediately decomposes into carbon dioxide and water:
H 2 CO 3 \u003d CO 2 + H 2 O

Finish the reaction equations, arrange the coefficients:
HNO 3 + Ca(OH) 2 =
HNO 3 + MgO =
HNO 3 + K 2 CO 3 =
H3PO4+KOH=
H3PO4 + BaO=
H3PO4 + Na 2 SiO 3 =

Consider the properties of the bases.

Soluble and insoluble bases differ in properties.

alkali + acid \u003d salt + water
(soluble base)+ Acid oxide \u003d salt + water
+ salt = another salt + another base
(should be precipitated)

Finish those reaction equations, arrange the coefficients :
Ca(OH)2+ CuCl 2
Ca(OH)2+ Al(NO 3) 3
Ca(OH)2 + ZnSO4

insoluble base + acid = salt + water
decomposes when heated = oxide + water

Finish the reaction equations, put the coefficients:

Cu(OH)2+ HCl
Zn(OH) 2+ H NO 3
Cu(OH)2 =

Consider the properties of salts:

Salt + acid = another salt + another acid
+ alkali = another salt + another base
+ salt = other salt + other salt
+ more active metal = different salt + different metal
(a precipitate should form in the first three reactions)

Complete the equations of possible reactions, arrange the coefficients, indicate the substance that precipitates:
ZnSO4 +KOH=
ZnSO4 +K3PO4=
ZnSO 4 + HNO 3 \u003d
Al(NO 3) 3 + HCl =
Al(NO 3) 3 + P 2 O 5 =
Al (NO 3) 3 + Ca (OH) 2 =
CuCl 2+Mg=
CuCl 2+ Hg =

Learn chemistry kids!



Wonderful! There is nothing complicated about ionic equations. You will need attentiveness and accuracy, and, of course, knowledge of the properties of the main classes of compounds, as already described above.

Remember: Oxides, water and insoluble substances do not dissociate into ions.

Let's get started. Suppose we have an equation

Mg(OH) 2 + 2HCl \u003d MgCl 2 + 2H 2 O

Now we need to consider the possibility of dissociation of each of the recorded substances and draw up an ionic equation. We look at the solubility table and look for Mg(OH)2. We see that it is insoluble. This means that we simply rewrite it

Mg(OH)2+ and move on. We are looking for in the solubility table HCl. We see that this substance is soluble. Wonderful! We write those ions that are written in the table:

Mg(OH)2+ H + + Cl - , but in the equation before Hcl there was a coefficient of 2, which means we have 2H + and 2 Cl -

Mg(OH)2 +2Н + + 2Cl -

But in the formula after chlorine there was index 2. So we have 2 chlorine. So in the equation we put 2 in front of the chlorine ion.

Mg(OH)2 + 2H + + 2Cl - \u003d Mg 2+ +2 Cl -

Now water. But we remember: water does not dissociate, we rewrite it as it is.

Mg(OH)2 + 2H + + 2Cl - \u003d Mg 2+ +2 Cl - + 2H2O

We have written down the complete ionic equation. HURRAH! Now we need to find the same ions on the left and right sides of the equation and cancel them, as in an algebraic equation.

Mg(OH)2 +2H++ 2Cl - \u003d Mg 2+ +2 Cl - + 2H2O

Rewriting without them

Mg(OH)2 + 2H + \u003d Mg 2+ +2H2O

We have an abbreviated ionic equation. As a result, our entry looks like this:

Mg(OH) 2 + 2HCl \u003d MgCl 2 + 2H 2 O

Mg(OH)2 + 2H + + 2Cl - \u003d Mg 2+ +2 Cl - + 2H2O

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

Congratulations. This is your first ionic equation. Hopefully not the last. Need to practice. First, use the ready-made equations:

2HNO 3 + Ca (OH) 2 \u003d Ca (NO 3) 2 + 2H 2 O
2HNO 3 + MgO \u003d Mg (NO 3) 2 + H 2 O
2HNO 3 + K 2 CO 3 \u003d 2KNO 3 + CO 2 + H 2 O Carbonic acid does not exist!

Check yourself, find mistakes

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

2H + + 2NO 3 - + Ca 2+ + 2OH - \u003d Ca 2+ + 2NO 3 - + 2H 2 O

2H + +2OH - \u003d 2H 2 O

2HNO 3 + MgO \u003d Mg (NO 3) 2 + H 2 O

2H + +2NO 3 - + MgO \u003d Mg 2+ + 2NO 3 - + H 2 O

2H + + MgO \u003d Mg 2+ + H 2 O

2HNO 3 + K 2 CO 3 \u003d 2KNO 3 + CO 2 + H 2 O

2H + + 2NO 3 - + 2 K + + CO 3 2- \u003d 2K + + 2NO 3 - + CO 2 + H 2 O

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

I hope there were few mistakes.

Practice some more. Finish the reaction equations, arrange the coefficients, write down the ionic equations:

ZnSO4 +

Predicting the properties of an element by position in the Periodic system e

main classes of inorganic substances
Ionic reaction equations

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