Displacement of metals. What is the most active metal? Practical use of the metal activity series

To analyze the activity of metals, either the electrochemical series of metal voltages or their position in the Periodic Table is used. The more active the metal, the easier it will donate electrons and the better it will be as a reducing agent in redox reactions.

Electrochemical series of voltages of metals.

Features of the behavior of some oxidizing and reducing agents.

a) oxygen-containing salts and acids of chlorine in reactions with reducing agents usually turn into chlorides:

b) if substances participate in the reaction in which the same element has a negative and positive oxidation state, they occur in the zero oxidation state (a simple substance is released).

Required skills.

1. Arrangement of oxidation states.
It must be remembered that the degree of oxidation is hypothetical the charge of an atom (i.e. conditional, imaginary), but it should not go beyond common sense. It can be integer, fractional, or zero.

Exercise 1:Arrange the oxidation states of the substances:

2. Arrangement of oxidation states in organic substances.
Remember that we are only interested in the oxidation states of those carbon atoms that change their environment in the redox process, while the total charge of the carbon atom and its non-carbon environment is taken as 0.

Task 2:Determine the oxidation state of the carbon atoms circled along with the non-carbon environment:

2-methylbutene-2: - =

acetic acid: -

3. Do not forget to ask yourself the main question: who donates electrons in this reaction, and who accepts them, and what do they turn into? So that it does not work that electrons arrive from nowhere or fly away to nowhere.

Example:

In this reaction, one must see that potassium iodide can be only reducing agent, so potassium nitrite will accept electrons, lowering its degree of oxidation.
Moreover, under these conditions (dilute solution) nitrogen goes from to the nearest oxidation state.

4. Drawing up an electronic balance is more difficult if the formula unit of a substance contains several atoms of an oxidizing or reducing agent.
In this case, this must be taken into account in the half-reaction by calculating the number of electrons.
The most common problem is with potassium dichromate, when it goes into the role of an oxidizing agent:

These deuces cannot be forgotten when calling, because they indicate the number of atoms of a given type in the equation.

Task 3:What coefficient should be put before and before

Task 4:What coefficient in the reaction equation will stand in front of magnesium?

5. Determine in which medium (acidic, neutral or alkaline) the reaction takes place.
This can be done either about the products of the reduction of manganese and chromium, or by the type of compounds that were obtained on the right side of the reaction: for example, if in the products we see acid, acid oxide- it means that this is definitely not an alkaline environment, and if metal hydroxide precipitates, it is definitely not acidic. And of course, if on the left side we see metal sulfates, and on the right - nothing like sulfur compounds - apparently, the reaction is carried out in the presence of sulfuric acid.

Task 5:Determine the environment and substances in each reaction:

6. Remember that water is a free traveler, it can both participate in the reaction and be formed.

Task 6:Which side of the reaction will the water be on? What will the zinc go to?

Task 7:Soft and hard oxidation of alkenes.
Add and equalize the reactions, after placing the oxidation states in organic molecules:

(cold solution)

(aqueous solution)

7. Sometimes a reaction product can be determined only by compiling an electronic balance and understanding which particles we have more:

Task 8:What other products will be available? Add and equalize the reaction:

8. What do the reagents turn into in the reaction?
If the schemes we have learned do not give an answer to this question, then we need to analyze which oxidizing agent and reducing agent in the reaction are strong or not?
If the oxidizer is of medium strength, it is unlikely that it can oxidize, for example, sulfur from to, usually oxidation only goes up to.
Conversely, if is a strong reducing agent and can recover sulfur from up to , then only up to .

Task 9:What will the sulfur turn into? Add and equalize the reactions:

9. Check that there is both an oxidizing agent and a reducing agent in the reaction.

Task 10:How many other products are in this reaction, and which ones?

10. If both substances can exhibit the properties of both a reducing agent and an oxidizing agent, you need to consider which of them more active oxidant. Then the second one will be the restorer.

Task 11:Which of these halogens is the oxidizing agent and which is the reducing agent?

11. If one of the reagents is a typical oxidizing agent or reducing agent, then the second one will “do his will”, either by donating electrons to the oxidizing agent or accepting from the reducing agent.

Hydrogen peroxide is a substance with dual nature, in the role of an oxidizing agent (which is more characteristic of it) passes into water, and as a reducing agent - passes into free gaseous oxygen.

Task 12:What role does hydrogen peroxide play in each reaction?

The sequence of arrangement of the coefficients in the equation.

First put down the coefficients obtained from the electronic balance.
Remember that you can double or reduce them only together. If any substance acts both as a medium and as an oxidizing agent (reducing agent), it will have to be equalized later, when almost all the coefficients are arranged.
Hydrogen is equalized penultimately, and we only check for oxygen!

1. Task 13:Add and equalize:

Take your time counting the oxygen atoms! Remember to multiply rather than add indices and coefficients.
The number of oxygen atoms on the left and right sides must converge!
If this does not happen (provided that you count them correctly), then there is a mistake somewhere.

Possible mistakes.

1. Arrangement of oxidation states: check each substance carefully.
Often mistaken in the following cases:

a) oxidation states in hydrogen compounds of non-metals: phosphine - oxidation state of phosphorus - negative;
b) in organic substances - check again whether the entire environment of the atom is taken into account;
c) ammonia and ammonium salts - they contain nitrogen always has an oxidation state;
d) oxygen salts and acids of chlorine - in them chlorine can have an oxidation state;
e) peroxides and superoxides - in them, oxygen does not have an oxidation state, it happens, and in - even;
f) double oxides: - they have metals two different oxidation states, usually only one of them is involved in the transfer of electrons.

Task 14:Add and equalize:

Task 15:Add and equalize:

2. The choice of products without taking into account the transfer of electrons - that is, for example, in the reaction there is only an oxidizing agent without a reducing agent, or vice versa.

Example: free chlorine is often lost in a reaction. It turns out that electrons came to manganese from outer space...

3. Incorrect products from a chemical point of view: a substance that interacts with the environment cannot be obtained!

a) in an acidic environment, metal oxide, base, ammonia cannot be obtained;
b) in an alkaline environment, acid or acid oxide will not be obtained;
c) an oxide, let alone a metal that reacts violently with water, is not formed in an aqueous solution.

Task 16:Find in reactions erroneous products, explain why they cannot be obtained under these conditions:

Answers and solutions to tasks with explanations.

Exercise 1:

Task 2:

2-methylbutene-2: - =

acetic acid: -

Task 3:

Since there are 2 chromium atoms in the dichromate molecule, they donate 2 times more electrons - i.e. 6.

Task 5:

If the environment is alkaline, then phosphorus will exist in the form of salt- potassium phosphate.

Task 6:

Since zinc is amphoteric metal, in alkaline solution it forms hydroxocomplex. As a result of the arrangement of the coefficients, it turns out that water must be present on the left side of the reaction:sulfuric acid (2 molecules).

Task 9:

(permanganate is not a very strong oxidizing agent in solution; note that water passes during adjustment to the right!)

(conc.)
(concentrated nitric acid is a very strong oxidizing agent)

Task 10:

Don't forget that manganese accepts electrons, wherein chlorine should give them away.
Chlorine is released in the form of a simple substance.

Task 11:

The higher the non-metal in the subgroup, the more active oxidizing agent, i.e. Chlorine is the oxidizing agent in this reaction. Iodine passes into the most stable positive oxidation state for it, forming iodic acid.

Sections: Chemistry, Competition "Presentation for the lesson"

Class: 11

Presentation for the lesson

Back forward

Attention! The slide preview is for informational purposes only and may not represent the full extent of the presentation. If you are interested in this work, please download the full version.

Goals and objectives:

Tutorial: Consideration of the chemical activity of metals based on the position in the periodic table D.I. Mendeleev and in the electrochemical voltage series of metals.
Developing: Contribute to the development of auditory memory, the ability to compare information, think logically and explain ongoing chemical reactions.
Educational: We form the skill of independent work, the ability to reasonably express one's opinion and listen to classmates, we instill in the children a sense of patriotism and pride in compatriots.

Equipment: PC with media projector, individual laboratories with a set of chemical reagents, models of crystal lattices of metals.

Lesson type: using technology for the development of critical thinking.

During the classes

I. Challenge stage.

Actualization of knowledge on the topic, the awakening of cognitive activity.

Bluff game: "Do you believe that ...". (Slide 3)

Metals occupy the upper left corner in the PSCE.
In crystals, metal atoms are bound by a metallic bond.
The valence electrons of metals are tightly bound to the nucleus.
Metals in the main subgroups (A) usually have 2 electrons in the outer level.
In the group from top to bottom there is an increase in the reducing properties of metals.
To assess the reactivity of a metal in solutions of acids and salts, it is enough to look at the electrochemical series of the voltages of metals.
To evaluate the reactivity of a metal in solutions of acids and salts, it is enough to look at the periodic table of D.I. Mendeleev

Question to the class? What does the entry mean? Me 0 - ne -\u003e Me + n(Slide 4)

Answer: Me0 - is a reducing agent, which means it interacts with oxidizing agents. The following can act as oxidizers:

Simple substances (+ O 2, Cl 2, S ...)
Complex substances (H 2 O, acids, salt solutions ...)

II. Understanding new information.

As a methodological technique, it is proposed to draw up a reference scheme.

Question to the class? What factors influence the reducing properties of metals? (Slide 5)

Answer: From the position in the periodic table of D.I. Mendeleev or from the position in the electrochemical series of the voltage of metals.

The teacher introduces the concepts: chemical activity and electrochemical activity.

Before starting the explanation, the children are invited to compare the activity of atoms To and Li position in the periodic table D.I. Mendeleev and the activity of simple substances formed by these elements according to their position in the electrochemical series of metal voltages. (Slide 6)

There is a contradiction:In accordance with the position of alkali metals in PSCE and according to the patterns of changes in the properties of elements in the subgroup, the activity of potassium is greater than that of lithium. In terms of position in the voltage series, lithium is the most active.

New material. The teacher explains the difference between chemical and electrochemical activity and explains that the electrochemical series of voltages reflects the ability of a metal to transform into a hydrated ion, where the measure of metal activity is energy, which consists of three terms (atomization energy, ionization energy and hydration energy). We write down the material in a notebook. (Slides 7-10)

Writing together in a notebook conclusion: The smaller the radius of the ion, the greater the electric field around it is created, the more energy is released during hydration, hence the stronger reducing properties of this metal in reactions.

History reference: presentation by a student on the creation by Beketov of a displacement series of metals. (Slide 11)

The action of the electrochemical voltage series of metals is limited only by the reactions of metals with electrolyte solutions (acids, salts).

Reminder:

The reducing properties of metals decrease during reactions in aqueous solutions under standard conditions (250°C, 1 atm.);
The metal to the left displaces the metal to the right of their salts in solution;
Metals standing up to hydrogen displace it from acids in solution (excl.: HNO3);
Me (to Al) + H 2 O -> alkali + H 2
Other Me (up to H 2) + H 2 O -> oxide + H 2 (harsh conditions)
Me (after H 2) + H 2 O -> do not react

(Slide 12)

The children are given notes.

Practical work:"Interaction of metals with salt solutions" (Slide 13)

Make the transition:

CuSO4 —> FeSO4
CuSO4 —> ZnSO4

Demonstration of the experience of interaction between copper and mercury (II) nitrate solution.

III. Reflection, contemplation.

We repeat: in which case we use the periodic table, and in which case a series of metal voltages is needed. (Slides 14-15).

We return to the initial questions of the lesson. We highlight questions 6 and 7 on the screen. We analyze which statement is not correct. On the screen - the key (check task 1). (Slide 16).

Summing up the lesson:

What have you learned?
In what case is it possible to use the electrochemical voltage series of metals?

Homework: (Slide 17)

To repeat the concept of "POTENTIAL" from the course of physics;
Finish the reaction equation, write the electronic balance equations: Cu + Hg (NO 3) 2 →
Given metals ( Fe, Mg, Pb, Cu)- offer experiments confirming the location of these metals in the electrochemical series of voltage.

We evaluate the results for the bluff game, work at the board, oral answers, communication, practical work.

Used Books:

O.S. Gabrielyan, G.G. Lysova, A.G. Vvedenskaya "Handbook for the teacher. Chemistry Grade 11, part II "Drofa Publishing House.
N.L. Glinka General Chemistry.

metals

Many chemical reactions involve simple substances, in particular metals. However, different metals exhibit different activity in chemical interactions, and it depends on this whether the reaction will proceed or not.

The greater the activity of a metal, the more vigorously it reacts with other substances. By activity, all metals can be arranged in a series, which is called the activity series of metals, or the displacement series of metals, or the series of metal voltages, as well as the electrochemical series of metal voltages. This series was first studied by the outstanding Ukrainian scientist M.M. Beketov, therefore this series is also called the Beketov series.

The activity series of Beketov's metals has the following form (the most commonly used metals are given):

K > Ca > Na > Mg > Al > Zn > Fe > Ni > Sn > Pb > > H 2 > Cu > Hg > Ag > Au.

In this series, the metals are arranged with decreasing activity. Among these metals, potassium is the most active, and gold is the least active. Using this series, you can determine which metal is more active from another. Hydrogen is also present in this series. Of course, hydrogen is not a metal, but in this series its activity is taken as a reference point (a kind of zero).

Interaction of metals with water

Metals are capable of displacing hydrogen not only from acid solutions, but also from water. Just as with acids, the activity of the interaction of metals with water increases from left to right.

Metals in the activity series up to magnesium are able to react with water under normal conditions. When these metals interact, alkalis and hydrogen are formed, for example:

Other metals that come before hydrogen in a number of activities can also interact with water, but this occurs under more severe conditions. For interaction, superheated water vapor is passed through hot metal filings. Under such conditions, hydroxides can no longer exist, therefore the reaction products are the oxide of the corresponding metal element and hydrogen:

The dependence of the chemical properties of metals on the place in the activity series

← metal activity increases

Displaces hydrogen from acids

Does not displace hydrogen from acids

Displace hydrogen from water, form alkalis

Displace hydrogen from water at high temperature, form oxides

3 do not interact with water

It is impossible to displace from an aqueous solution of salt

Can be obtained by displacing a more active metal from a salt solution or from an oxide melt

The interaction of metals with salts

If the salt is soluble in water, then a metal atom in it can be replaced by an atom of a more active element. If an iron plate is immersed in a solution of cuprum (II) sulfate, then after a while copper will be released on it in the form of a red coating:

But if a silver plate is immersed in a solution of cuprum (II) sulfate, then no reaction will occur:

Cuprum can be displaced by any metal that is to the left of the metal activity series. However, the metals that are at the very beginning of the series are sodium, potassium, etc. - are not suitable for this, because they are so active that they will interact not with salt, but with water in which this salt is dissolved.

The displacement of metals from salts by more active metals is widely used in industry for the extraction of metals.

Interaction of metals with oxides

Oxides of metallic elements are able to interact with metals. More active metals displace less active ones from oxides:

But, unlike the interaction of metals with salts, in this case, the oxides must be melted for the reaction to occur. For the extraction of metal from oxide, you can use any metal that is located in the activity row to the left, even the most active sodium and potassium, because water is not contained in the molten oxide.

The interaction of metals with oxides is used in industry to extract other metals. The most practical metal for this method is aluminum. It is quite widespread in nature and cheap to manufacture. You can also use more active metals (calcium, sodium, potassium), but, firstly, they are more expensive than aluminum, and secondly, due to their ultra-high chemical activity, it is very difficult to store them in factories. This method of extracting metals using aluminum is called aluminothermy.

When people hear the word "metal", it is usually associated with a cold and solid substance that conducts electricity. However, metals and their alloys can be very different from each other. There are those that belong to the heavy group, these substances have the highest density. And some, such as lithium, are so light that they could float in water if only they did not actively react with it.

What metals are the most active?

But which metal exhibits the most intense properties? The most active metal is cesium. In terms of activity among all metals, it ranks first. Also, his "brothers" are considered francium, which is in second place, and ununenniy. But little is known about the properties of the latter.

Cesium properties

Cesium is an element that is similarly easy to melt in the hands. True, this can be done only under one condition: if the cesium is in a glass ampoule. Otherwise, the metal can quickly react with the surrounding air - ignite. And the interaction of cesium with water is accompanied by an explosion - such is the most active metal in its manifestation. This is the answer to the question of why it is so difficult to put cesium into containers.

In order to place it inside a test tube, it is necessary that it be made of special glass and filled with argon or hydrogen. The melting point of cesium is 28.7 o C. At room temperature, the metal is in a semi-liquid state. Cesium is a golden-white substance. In the liquid state, the metal reflects light well. Cesium vapor has a greenish-blue tint.

How was cesium discovered?

The most active metal was the first chemical element, the presence of which in the surface of the earth's crust was detected using the method of spectral analysis. When the scientists received the spectrum of the metal, they saw two sky-blue lines in it. Thus, this element got its name. The word caesius in Latin means "sky blue".

Discovery history

Its discovery belongs to the German researchers R. Bunsen and G. Kirchhoff. Even then, scientists were interested in which metals are active and which are not. In 1860, researchers studied the composition of water from the Durkheim Reservoir. They did this with the help of spectral analysis. In a water sample, scientists found elements such as strontium, magnesium, lithium, and calcium.

Then they decided to analyze a drop of water with a spectroscope. Then they saw two bright blue lines, located not far from each other. One of them practically coincided with the line of strontium metal in its position. Scientists decided that the substance they identified was unknown and attributed it to the group of alkali metals.

In the same year, Bunsen wrote a letter to his colleague, photochemist G. Roscoe, in which he spoke about this discovery. And officially, cesium was announced on May 10, 1860 at a meeting of scientists at the Berlin Academy. After six months, Bunsen was able to isolate about 50 grams of cesium chloroplatinite. Scientists processed 300 tons of mineral water and isolated about 1 kg of lithium chloride as a by-product in order to ultimately obtain the most active metal. This suggests that there is very little cesium in mineral waters.

The difficulty of obtaining cesium is constantly pushing scientists to search for minerals containing it, one of which is pollucite. But the extraction of cesium from ores is always incomplete; during operation, cesium dissipates very quickly. This makes it one of the most inaccessible substances in metallurgy. The earth's crust, for example, contains 3.7 grams of cesium per ton. And in one liter of sea water, only 0.5 micrograms of a substance is the most active metal. This leads to the fact that the extraction of cesium is one of the most labor-intensive processes.

Receipt in Russia

As mentioned, the main mineral from which cesium is obtained is pollucite. And also this most active metal can be obtained from a rare avogadrite. In industry, it is pollucite that is used. It was not mined in Russia after the collapse of the Soviet Union, despite the fact that even at that time gigantic reserves of cesium were discovered in the Voronya tundra near Murmansk.

By the time the domestic industry could afford to extract cesium, the license to develop this deposit was acquired by a company from Canada. Now the extraction of cesium is carried out by the Novosibirsk company CJSC Rare Metals Plant.

Use of cesium

This metal is used to make various solar cells. And also cesium compounds are used in special branches of optics - in the manufacture of infrared devices, cesium is used in the manufacture of sights that allow you to notice the equipment and manpower of the enemy. It is also used to make special metal halide lamps.

But this does not exhaust the scope of its application. On the basis of cesium, a number of medicines have also been created. These are drugs for the treatment of diphtheria, peptic ulcers, shock and schizophrenia. Like lithium salts, cesium salts have normothymic properties - or, simply, they are able to stabilize the emotional background.

francium metal

Another of the metals with the most intense properties is francium. It got its name in honor of the motherland of the discoverer of metal. M. Pere, who was born in France, discovered a new chemical element in 1939. It is one of those elements about which even chemists themselves find it difficult to draw any conclusions.

Francium is the heaviest metal. At the same time, the most active metal is francium, along with cesium. Francium possesses this rare combination - high chemical activity and low nuclear stability. Its longest-lived isotope has a half-life of only 22 minutes. Francium is used to detect another element - actinium. As well as francium salts, it was previously proposed to use for the detection of cancerous tumors. However, due to the high cost, this salt is unprofitable to produce.

Comparison of the most active metals

Ununennium is not yet a discovered metal. It will rank first in the eighth row of the periodic table. The development and research of this element is carried out in Russia at the Joint Institute for Nuclear Research. This metal will also have to have a very high activity. If we compare the already known francium and cesium, then francium will have the highest ionization potential - 380 kJ / mol.

For cesium, this figure is 375 kJ/mol. But francium still does not react as quickly as cesium. Thus, cesium is the most active metal. This is the answer (chemistry is most often the subject in the curriculum of which you can find a similar question), which can be useful both in the classroom at school and in vocational school.

Physical and chemical expressions of portions, proportions and amounts of a substance. Atomic mass unit, a.m.u. A mole of a substance, Avogadro's constant. Molar mass. Relative atomic and molecular weight of a substance. Mass fraction of a chemical element

The structure of matter. Nuclear model of the structure of the atom. The state of an electron in an atom. Electron filling of orbitals, principle of least energy, Klechkovsky's rule, Pauli's principle, Hund's rule

Periodic law in the modern formulation. Periodic system. The physical meaning of the periodic law. The structure of the periodic system. Changing the properties of atoms of chemical elements of the main subgroups. Plan for the characteristics of a chemical element.

Periodic system of Mendeleev. higher oxides. Volatile hydrogen compounds. Solubility, relative molecular weights of salts, acids, bases, oxides, organic substances. Series of electronegativity, anions, activity and voltages of metals

You are here now: Electrochemical series of activity of metals and hydrogen table, electrochemical series of voltages of metals and hydrogen, series of electronegativity of chemical elements, series of anions

Chemical bond. Concepts. Octet rule. Metals and non-metals. Hybridization of electron orbitals. Valence electrons, the concept of valence, the concept of electronegativity

Types of chemical bond. Covalent bond - polar, non-polar. Characteristics, formation mechanisms and types of covalent bonds. Ionic bond. The degree of oxidation. Metal connection. Hydrogen bond.

Chemical reactions. Concepts and features, Law of conservation of mass, Types (compounds, expansions, substitutions, exchanges). Classification: Reversible and irreversible, Exothermic and endothermic, Redox, Homogeneous and heterogeneous

The most important classes of inorganic substances. Oxides. Hydroxides. Salt. Acids, bases, amphoteric substances. Major acids and their salts. Genetic connection of the most important classes of inorganic substances.

Chemistry of non-metals. Halogens. Sulfur. Nitrogen. Carbon. inert gases

Chemistry of metals. alkali metals. Group IIA elements. Aluminum. Iron

Patterns of the course of chemical reactions. The rate of a chemical reaction. The law of active masses. Van't Hoff's rule. Reversible and irreversible chemical reactions. chemical balance. Le Chatelier's principle. Catalysis

Solutions. electrolytic dissociation. Concepts, solubility, electrolytic dissociation, theory of electrolytic dissociation, degree of dissociation, dissociation of acids, bases and salts, neutral, alkaline and acidic environment

Reactions in electrolyte solutions + Redox reactions. (Ion exchange reactions. Formation of a poorly soluble, gaseous, low-dissociating substance. Hydrolysis of aqueous solutions of salts. Oxidizing agent. Reducing agent.)

Classification of organic compounds. Hydrocarbons. Derivatives of hydrocarbons. Isomerism and homology of organic compounds

The most important derivatives of hydrocarbons: alcohols, phenols, carbonyl compounds, carboxylic acids, amines, amino acids