11 acids in chemistry. Acid presentation for a lesson in chemistry (Grade 11) on the topic. Reference material for passing the test

Acids are such chemical compounds that are capable of donating an electrically charged hydrogen ion (cation), as well as accepting two interacting electrons, as a result of which a covalent bond.

In this article, we will look at the main acids that are studied in the middle classes. general education schools, and also find out the set interesting facts on various acids. Let's get started.

Acids: types

In chemistry, there are many different acids that have a variety of properties. Chemists distinguish acids by their oxygen content, volatility, solubility in water, strength, stability, belonging to an organic or inorganic class of chemical compounds. In this article, we will look at a table that presents the most famous acids. The table will help you remember the name of the acid and its chemical formula.

So, everything is clearly visible. This table presents the most famous acids in the chemical industry. The table will help you remember the names and formulas much faster.

Hydrosulphuric acid

H 2 S is hydrosulfide acid. Its peculiarity lies in the fact that it is also a gas. Hydrogen sulfide is very poorly soluble in water, and also interacts with many metals. Hydrosulphuric acid belongs to the group of "weak acids", examples of which we will consider in this article.

H 2 S has a slightly sweet taste and a very strong smell of rotten eggs. In nature, it can be found in natural or volcanic gases, and it is also released when protein rots.

The properties of acids are very diverse, even if the acid is indispensable in industry, it can be very unhealthy for human health. This acid is highly toxic to humans. When a small amount of hydrogen sulfide is inhaled, a person awakens headache, severe nausea and dizziness begin. If a person breathes a large number of H 2 S, this can lead to convulsions, coma or even instant death.

Sulfuric acid

H 2 SO 4 is a strong sulfuric acid that children get acquainted with in chemistry lessons as early as the 8th grade. Chemical acids such as sulfuric are very strong oxidizing agents. H 2 SO 4 acts as an oxidizing agent on many metals, as well as basic oxides.

H 2 SO 4 causes chemical burns on contact with skin or clothing, but is not as toxic as hydrogen sulfide.

Nitric acid

Strong acids are very important in our world. Examples of such acids: HCl, H 2 SO 4 , HBr, HNO 3 . HNO 3 is the well-known nitric acid. It has found wide application in industry as well as in agriculture. It is used for the manufacture of various fertilizers, in jewelry, in printing photographs, in the production of medicines and dyes, as well as in the military industry.

Chemical acids such as nitric acid are very harmful to the body. Vapors of HNO 3 leave ulcers, cause acute inflammation and irritation of the respiratory tract.

Nitrous acid

Nitrous acid is often confused with nitric acid, but there is a difference between them. The fact is that it is much weaker than nitrogen, it has completely different properties and effects on the human body.

HNO 2 has found wide application in the chemical industry.

Hydrofluoric acid

Hydrofluoric acid (or hydrogen fluoride) is a solution of H 2 O with HF. The formula of the acid is HF. Hydrofluoric acid is very actively used in the aluminum industry. It dissolves silicates, etchs silicon, silicate glass.

Hydrogen fluoride is very harmful to the human body, depending on its concentration it can be a light drug. When it comes into contact with the skin, at first there are no changes, but after a few minutes, a sharp pain and a chemical burn may appear. Hydrofluoric acid is very harmful to the environment.

Hydrochloric acid

HCl is hydrogen chloride and is a strong acid. Hydrogen chloride retains the properties of acids belonging to the group of strong acids. In appearance, the acid is transparent and colorless, but smokes in air. Hydrogen chloride is widely used in the metallurgical and food industries.

This acid causes chemical burns, but it is especially dangerous if it gets into the eyes.

Phosphoric acid

Phosphoric acid (H 3 PO 4) is a weak acid in its properties. But even weak acids can have the properties of strong ones. For example, H 3 PO 4 is used in industry to recover iron from rust. In addition, phosphoric (or phosphoric) acid is widely used in agriculture - a wide variety of fertilizers are made from it.

The properties of acids are very similar - almost each of them is very harmful to the human body, H 3 PO 4 is no exception. For example, this acid also causes severe chemical burns, nosebleeds, and tooth decay.

Carbonic acid

H 2 CO 3 is a weak acid. It is obtained by dissolving CO 2 (carbon dioxide) in H 2 O (water). Carbonic acid is used in biology and biochemistry.

Density of various acids

The density of acids occupies an important place in the theoretical and practical parts of chemistry. Thanks to the knowledge of density, it is possible to determine the concentration of a particular acid, solve chemical problems and add the correct amount of acid to complete the reaction. The density of any acid varies with concentration. For example, the greater the percentage of concentration, the greater the density.

General properties of acids

Absolutely all acids are (that is, they consist of several elements of the periodic table), while they necessarily include H (hydrogen) in their composition. Next, we will look at which are common:

All oxygen-containing acids (in the formula of which O is present) form water during decomposition, and also anoxic acids decompose into simple substances (for example, 2HF decomposes into F 2 and H 2).
Oxidizing acids interact with all metals in the metal activity series (only with those located to the left of H).
They interact with various salts, but only with those that were formed by an even weaker acid.

By their own physical properties acids are very different from each other. After all, they can have a smell and not have it, and also be in a variety of states of aggregation: liquid, gaseous and even solid. Solid acids are very interesting for studying. Examples of such acids: C 2 H 2 0 4 and H 3 BO 3.

Concentration

Concentration is a quantity that determines the quantitative composition of any solution. For example, chemists often need to determine how much pure sulfuric acid is in dilute H 2 SO 4 acid. To do this, they pour a small amount of dilute acid into a beaker, weigh it, and determine the concentration from a density table. The concentration of acids is closely related to the density, often there are calculation tasks to determine the concentration, where you need to determine the percentage of pure acid in the solution.

Classification of all acids according to the number of H atoms in their chemical formula

One of the most popular classifications is the division of all acids into monobasic, dibasic and, accordingly, tribasic acids. Examples of monobasic acids: HNO 3 (nitric), HCl (hydrochloric), HF (hydrofluoric) and others. These acids are called monobasic, since only one H atom is present in their composition. There are many such acids, it is impossible to remember absolutely every one. You just need to remember that acids are also classified by the number of H atoms in their composition. Dibasic acids are defined similarly. Examples: H 2 SO 4 (sulphuric), H 2 S (hydrogen sulfide), H 2 CO 3 (coal) and others. Tribasic: H 3 PO 4 (phosphoric).

Basic classification of acids

One of the most popular classifications of acids is their division into oxygen-containing and anoxic acids. How to remember, without knowing the chemical formula of a substance, that it is an oxygen-containing acid?

All oxygen-free acids in the composition lack the important element O - oxygen, but they contain H. Therefore, the word "hydrogen" is always attributed to their name. HCl is a H 2 S - hydrogen sulfide.

But even by the names of acid-containing acids, you can write a formula. For example, if the number of O atoms in a substance is 4 or 3, then the suffix -n- is always added to the name, as well as the ending -aya-:

H 2 SO 4 - sulfuric (number of atoms - 4);
H 2 SiO 3 - silicon (number of atoms - 3).

If the substance has less than three oxygen atoms or three, then the suffix -ist- is used in the name:

HNO 2 - nitrogenous;
H 2 SO 3 - sulfurous.

General properties

All acids taste sour and often slightly metallic. But there are other similar properties, which we will now consider.

There are substances that are called indicators. Indicators change their color, or the color remains, but its hue changes. This happens when some other substances, such as acids, act on the indicators.

An example of a color change is such a product familiar to many as tea and citric acid. When lemon is thrown into tea, the tea gradually begins to noticeably lighten. This is due to the fact that lemon contains citric acid.

There are other examples as well. Litmus, which in a neutral medium has a lilac color, turns red when hydrochloric acid is added.

With tensions up to hydrogen in the series, gas bubbles are released - H. However, if a metal that is in the tension series after H is placed in a test tube with acid, then no reaction will occur, there will be no gas evolution. So, copper, silver, mercury, platinum and gold will not react with acids.

In this article, we examined the most famous chemical acids, as well as their main properties and differences.

Sour taste, action on indicators, electrical conductivity, interaction with metals, basic and amphoteric oxides, bases and salts, formation esters with alcohols - these properties are common to inorganic and organic acids.

1. In water, acids dissociate into hydrogen cations and anions of acid residues, for example:

Acid solutions change the color of indicators: litmus - to red, methyl orange - to pink, the color of phenolphthalein does not change.

2. Solutions of acids react with metals standing in the electrochemical series of voltages to the left of hydrogen, subject to a number of conditions, the most important of which is the formation as a result of the reaction soluble salt. Considering this property of inorganic and organic acids, we emphasize that the interaction of HNO 3 and H 2 SO 4 (conc.) with metals (Table 19) proceeds differently, but these features of these acids will be explained somewhat later.

Table 19
Interaction Products
simple substances with nitric and sulfuric acids

3. Inorganic and organic acids interact with basic and amphoteric oxides, provided that a soluble salt is formed:

4. Both those and other acids react with bases. Polybasic acids can form both medium and acidic salts (these are neutralization reactions):

5. The reaction between acids and salts occurs only if a gas or precipitate is formed:

The interaction of phosphoric acid H 2 PO 4 with limestone will stop due to the formation of an insoluble precipitate of calcium phosphate Ca 3 (PO 4) 2 on the surface of the last.

6. Esters form not only organic acids according to the general equation:

but also inorganic acids, such as nitric and sulfuric:

A similar reaction with the participation of two and three hydroxo groups of cellulose during its nitration leads to the production of esters: di- and trinitrocellulose - the necessary substances for the production of smokeless powder.

At the same time, individual representatives of mineral and organic acids also have special properties.

The features of the properties of nitric HNO 3 and concentrated sulfuric H 2 SO 4 (conc.) acids are due to the fact that when they interact with simple substances (metals and non-metals), not H + cations, but nitrate and sulfate ions will act as oxidizing agents. It is logical to expect that as a result of such reactions, not hydrogen H 2 is formed, but other substances are obtained: necessarily salt and water, as well as one of the products of the reduction of nitrate or sulfate ions, depending on the concentration of acids, the position of the metal in a series of voltages and reaction conditions (temperature, metal fineness, etc.).

It should be noted that the third product of the reaction of metals with these acids is often formed in a "bouquet" - a mixture with other products, but in Table 19 we indicated the predominant products.

These features of the chemical behavior of HNO 3 and H 2 SO 4 (conc.) clearly illustrate the thesis of the theory chemical structure about the mutual influence of atoms in the molecules of substances. It can also be traced on the example of the properties of organic acids, such as acetic and formic.

Acetic acid CH 3 COOH, like other carboxylic acids, contains a hydrocarbon radical in the molecule. In it, reactions of substitution of hydrogen atoms by halogen atoms are possible:

Under the influence of halogen atoms in the acid molecule, its degree of dissociation greatly increases. For example, chloroacetic acid is almost 100 times stronger than acetic acid (why?).

Formic acid HCOOH, unlike acetic acid, does not have a hydrocarbon radical in the molecule. Instead, it contains a hydrogen atom, and therefore is a substance with a dual function - aldehyde acid and, unlike other carboxylic acids, gives the "silver mirror" reaction:

The resulting carbonic acid H 2 CO 3 decomposes into water and carbon dioxide, which in excess of ammonia turns into ammonium bicarbonate.

Bases, amphoteric hydroxides

Bases are complex substances consisting of metal atoms and one or more hydroxo groups (-OH). General formula Me + y (OH) y, where y is the number of hydroxo groups equal to the oxidation state of the Me metal. The table shows the classification of bases.

Properties of alkali hydroxides of alkali and alkaline earth metals

1. Aqueous solutions of alkalis are soapy to the touch, change the color of the indicators: litmus - in Blue colour, phenolphthalein - in crimson.

2. Aqueous solutions dissociate:

3. Interact with acids, entering into an exchange reaction:

Polyacid bases can give intermediate and basic salts:

4. Interact with acid oxides, forming medium and acid salts, depending on the basicity of the acid corresponding to this oxide:

5. Interact with amphoteric oxides and hydroxides:

a) fusion:

b) in solutions:

6. React with water-soluble salts if a precipitate or gas is formed:

Insoluble bases (Cr (OH) 2, Mn (OH) 2, etc.) interact with acids and decompose when heated:

Amphoteric hydroxides

Compounds are called amphoteric, which, depending on the conditions, can be both donors of hydrogen cations and exhibit acidic properties, and their acceptors, i.e., exhibit basic properties.

Chemical properties of amphoteric compounds

1. Interacting with strong acids, they reveal the main properties:

Zn(OH) 2 + 2HCl = ZnCl 2 + 2H 2 O

2. Interacting with alkalis - strong bases, they exhibit acidic properties:

Zn (OH) 2 + 2NaOH \u003d Na 2 ( complex salt)

Al (OH) 3 + NaOH \u003d Na ( complex salt)

Compounds are called complex in which at least one covalent bond was formed by the donor-acceptor mechanism.

The general method for obtaining bases is based on exchange reactions, by which both insoluble and soluble bases can be obtained.

CuSO 4 + 2KOH \u003d Cu (OH) 2 ↓ + K 2 SO 4

K 2 CO 3 + Ba (OH) 2 \u003d 2 KOH + BaCO 3 ↓

When soluble bases are obtained by this method, an insoluble salt precipitates.

When obtaining water-insoluble bases with amphoteric properties, an excess of alkali should be avoided, since dissolution of the amphoteric base may occur, for example:

AlCl 3 + 4KOH \u003d K [Al (OH) 4] + 3KSl

In such cases, ammonium hydroxide is used to obtain hydroxides, in which amphoteric hydroxides do not dissolve:

AlCl 3 + 3NH 3 + ZH 2 O \u003d Al (OH) 3 ↓ + 3NH 4 Cl

Hydroxides of silver and mercury decompose so easily that when you try to obtain them by an exchange reaction, instead of hydroxides, oxides precipitate:

2AgNO 3 + 2KOH \u003d Ag 2 O ↓ + H 2 O + 2KNO 3

In industry, alkalis are usually obtained by electrolysis of aqueous solutions of chlorides.

2NaCl + 2H 2 O → ϟ → 2NaOH + H 2 + Cl 2

Alkalis can also be obtained by reacting alkali and alkaline earth metals or their oxides with water.

2Li + 2H 2 O \u003d 2LiOH + H 2

SrO + H 2 O \u003d Sr (OH) 2

acids

Acids are called complex substances, the molecules of which consist of hydrogen atoms that can be replaced by metal atoms, and acid residues. Under normal conditions, acids can be solid (phosphoric H 3 PO 4; silicon H 2 SiO 3) and liquid (sulfuric acid H 2 SO 4 will be a pure liquid).

Gases such as hydrogen chloride HCl, hydrogen bromide HBr, hydrogen sulfide H 2 S form the corresponding acids in aqueous solutions. The number of hydrogen ions formed by each acid molecule during dissociation determines the charge of the acid residue (anion) and the basicity of the acid.

According to protolytic theory of acids and bases, proposed simultaneously by the Danish chemist Bronsted and the English chemist Lowry, an acid is a substance splitting off with this reaction protons, A basis- a substance capable of receive protons.

acid → base + H +

Based on these ideas, it is clear basic properties of ammonia, which, due to the presence of a lone electron pair at the nitrogen atom, effectively accepts a proton when interacting with acids, forming an ammonium ion through a donor-acceptor bond.

HNO 3 + NH 3 ⇆ NH 4 + + NO 3 -

acid base acid base

A more general definition of acids and bases proposed by the American chemist G. Lewis. He suggested that acid-base interactions are quite do not necessarily occur with protone transfer. In the determination of acids and bases according to Lewis, the main role in chemical reactions assigned electronic steam.

Cations, anions, or neutral molecules that can accept one or more pairs of electrons are called Lewis acids.

For example, aluminum fluoride AlF 3 is an acid, since it is able to accept an electron pair when interacting with ammonia.

AlF 3 + :NH 3 ⇆ :

Cations, anions or neutral molecules capable of donating electron pairs are called Lewis bases (ammonia is a base).

The Lewis definition covers all acid-base processes that have been considered by the previously proposed theories. The table compares the definitions of acids and bases currently in use.

Nomenclature of acids

Since there are different definitions of acids, their classification and nomenclature are rather arbitrary.

According to the number of hydrogen atoms capable of splitting off in an aqueous solution, acids are divided into monobasic(e.g. HF, HNO 2), dibasic(H 2 CO 3 , H 2 SO 4) and tribasic(H 3 RO 4).

According to the composition of the acid is divided into anoxic(HCl, H 2 S) and oxygen-containing(HClO 4 , HNO 3).

Usually names of oxygenated acids derived from the name of a non-metal with the addition of the endings -kai, -way, if the oxidation state of the non-metal is equal to the group number. As the oxidation state decreases, the suffixes change (in order of decreasing metal oxidation state): - oval, ististaya, - ovate:

If we consider the polarity of the hydrogen-non-metal bond within a period, we can easily relate the polarity of this bond to the position of the element in the Periodic Table. From metal atoms that easily lose valence electrons, hydrogen atoms accept these electrons, forming a stable two-electron shell like the shell of a helium atom, and give ionic metal hydrides.

In hydrogen compounds of elements of groups III-IV of the Periodic system, boron, aluminum, carbon, silicon form covalent, weakly polar bonds with hydrogen atoms that are not prone to dissociation. For elements of groups V-VII Periodic system within a period, the polarity of the non-metal-hydrogen bond increases with the charge of the atom, but the distribution of charges in the resulting dipole is different than in hydrogen compounds of elements that tend to donate electrons. Atoms of non-metals, in which several electrons are needed to complete the electron shell, pull towards themselves (polarize) a pair of bond electrons the stronger, the greater the charge of the nucleus. Therefore, in the series CH 4 - NH 3 - H 2 O - HF or SiH 4 - PH 3 - H 2 S - Hcl, bonds with hydrogen atoms, while remaining covalent, become more polar, and the hydrogen atom in the dipole of the element-hydrogen bond becomes more electropositive. If polar molecules are in a polar solvent, the process of electrolytic dissociation can occur.

Let us discuss the behavior of oxygen-containing acids in aqueous solutions. These acids have N-O-E connection and, of course, the polarity of the H-O bond is affected by O-E connection. Therefore, these acids dissociate, as a rule, more easily than water.

H 2 SO 3 + H 2 O ⇆ H s O + + HSO 3

HNO 3 + H 2 O ⇆ H s O + + NO 3

Let's look at a few examples properties of oxygenated acids, formed by elements that are capable of exhibiting different oxidation states. It is known that hypochlorous acid HClO very weak hydrochloric acid HClO 2 also weak but stronger than hypochlorous, hypochlorous acid HclO 3 strong. Perchloric acid HClO 4 is one of the the strongest inorganic acids.

Dissociation according to the acid type (with elimination of the H ion) requires a break O-N connections. How can one explain the decrease in the strength of this bond in the series HClO - HClO 2 - HClO 3 - HClO 4? In this series, the number of oxygen atoms associated with the central chlorine atom increases. Each time a new bond of oxygen with chlorine is formed, an electron density is drawn away from the chlorine atom, and hence from the single O-Cl bond. As a result, the electron density partially leaves the О-Н bond, which is weakened because of this.

Such a pattern - gain acid properties with an increase in the degree of oxidation of the central atom - characteristic not only for chlorine, but also for other elements. For example, nitric acid HNO 3 , in which the nitrogen oxidation state is +5, is stronger than nitrous acid HNO 2 (nitrogen oxidation state is +3); sulfuric acid H 2 SO 4 (S +6) is stronger than sulfurous acid H 2 SO 3 (S +4).

Obtaining acids

1. Anoxic acids can be obtained in the direct combination of non-metals with hydrogen.

H 2 + Cl 2 → 2HCl,

H 2 + S ⇆ H 2 S

2. Some oxygenated acids can be obtained interaction of acid oxides with water.

3. Both anoxic and oxygenated acids can be obtained according to exchange reactions between salts and other acids.

BaBr 2 + H 2 SO 4 \u003d BaSO 4 ↓ + 2HBr

CuSO 4 + H 2 S \u003d H 2 SO 4 + CuS ↓

FeS + H 2 SO 4 (pa zb) \u003d H 2 S + FeSO 4

NaCl (T) + H 2 SO 4 (conc) = HCl + NaHSO 4

AgNO 3 + HCl = AgCl↓ + HNO 3

CaCO 3 + 2HBr \u003d CaBr 2 + CO 2 + H 2 O

4. Some acids can be obtained using redox reactions.

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

3P + 5HNO 3 + 2H 2 O \u003d ZH 3 RO 4 + 5NO 2

Sour taste, action on indicators, electrical conductivity, interaction with metals, basic and amphoteric oxides, bases and salts, formation of esters with alcohols - these properties are common to inorganic and organic acids.

can be divided into two types of reactions:

1) are common For acids the reactions are associated with the formation of hydronium ion H 3 O + in aqueous solutions;

2) specific(i.e. characteristic) reactions specific acids.

The hydrogen ion can enter into redox reactions, reducing to hydrogen, as well as in a compound reaction with negatively charged or neutral particles having lone pairs of electrons, i.e. in acid-base reactions.

TO general properties acids include the reactions of acids with metals in the series of voltages up to hydrogen, for example:

Zn + 2Н + = Zn 2+ + Н 2

Acid-base reactions include reactions with basic oxides and bases, as well as with medium, basic, and sometimes acidic salts.

2 CO 3 + 4HBr \u003d 2CuBr 2 + CO 2 + 3H 2 O

Mg (HCO 3) 2 + 2HCl \u003d MgCl 2 + 2CO 2 + 2H 2 O

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

Note that polybasic acids dissociate stepwise, and at each next step, dissociation is more difficult, therefore, with an excess of acid, acidic salts are most often formed, rather than medium ones.

Ca 3 (PO 4) 2 + 4H 3 PO 4 \u003d 3Ca (H 2 PO 4) 2

Na 2 S + H 3 PO 4 = Na 2 HPO 4 + H 2 S

NaOH + H 3 PO 4 = NaH 2 PO 4 + H 2 O

KOH + H 2 S \u003d KHS + H 2 O

At first glance, the formation of acidic salts may seem surprising. monobasic hydrofluoric (hydrofluoric) acid. However, this fact can be explained. Unlike all other hydrohalic acids, hydrofluoric acid is partially polymerized in solutions (due to the formation of hydrogen bonds) and different particles (HF) X can be present in it, namely H 2 F 2, H 3 F 3, etc.

A special case of acid-base balance - reactions of acids and bases with indicators that change color depending on the acidity of the solution. Indicators are used in qualitative analysis for the detection of acids and bases in solutions.

The most commonly used indicators are litmus(V neutral environment purple, V sour - red, V alkaline - blue), methyl orange(V sour environment red, V neutral - orange, V alkaline - yellow), phenolphthalein(V strongly alkaline environment crimson red, V neutral and acidic - colorless).

Specific properties different acids can be of two types: first, the reactions leading to the formation insoluble salts, and, secondly, redox transformations. If the reactions associated with the presence of an H + ion in them are common to all acids (qualitative reactions for detecting acids), specific reactions are used as qualitative reactions for individual acids:

Ag + + Cl - = AgCl (white precipitate)

Ba 2+ + SO 4 2- \u003d BaSO 4 (white precipitate)

3Ag + + PO 4 3 - = Ag 3 PO 4 (yellow precipitate)

Some specific reactions of acids are due to their redox properties.

Anoxic acids in aqueous solution can only oxidize.

2KMnO 4 + 16HCl \u003d 5Cl 2 + 2KCl + 2MnCl 2 + 8H 2 O

H 2 S + Br 2 \u003d S + 2HBg

Oxygen-containing acids can only be oxidized if the central atom in them is in a lower or intermediate oxidation state, as, for example, in sulfurous acid:

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

Many oxygen-containing acids, in which the central atom has the maximum oxidation state (S +6, N +5, Cr +6), exhibit the properties of strong oxidizing agents. Concentrated H 2 SO 4 is a strong oxidizing agent.

Cu + 2H 2 SO 4 (conc) = CuSO 4 + SO 2 + 2H 2 O

Pb + 4HNO 3 \u003d Pb (NO 3) 2 + 2NO 2 + 2H 2 O

C + 2H 2 SO 4 (conc) = CO 2 + 2SO 2 + 2H 2 O

It should be remembered that:

Acid solutions react with metals that are in the electrochemical series of voltages to the left of hydrogen, subject to a number of conditions, the most important of which is the formation of a soluble salt as a result of the reaction. The interaction of HNO 3 and H 2 SO 4 (conc.) with metals proceeds differently.

Concentrated sulfuric acid in the cold passivates aluminum, iron, chromium.

In water, acids dissociate into hydrogen cations and anions of acid residues, for example:

Inorganic and organic acids interact with basic and amphoteric oxides, provided that a soluble salt is formed:

Both those and other acids react with bases. Polybasic acids can form both medium and acidic salts (these are neutralization reactions):

The reaction between acids and salts occurs only if a precipitate or gas is formed:

The interaction of H 3 PO 4 with limestone will stop due to the formation of the last insoluble precipitate Ca 3 (PO 4) 2 on the surface.

These features of the chemical behavior of HNO 3 and H 2 SO 4 (conc.) clearly illustrate the thesis of the theory of chemical structure about the mutual influence of atoms in the molecules of substances.

The concepts of volatility and stability (stability) are often confused. Volatile acids are called acids, the molecules of which easily pass into a gaseous state, that is, they evaporate. For example, hydrochloric acid is a volatile but persistent, stable acid. The volatility of unstable acids cannot be judged. For example, non-volatile, insoluble silicic acid decomposes into water and SiO 2 . Aqueous solutions of hydrochloric, nitric, sulfuric, phosphoric and a number of other acids are colorless. Water solution chromic acid H 2 CrO 4 is yellow, permanganic acid HMnO 4 is raspberry.

Reference material to pass the test:

Mendeleev table

Solubility table

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Slides captions:

Teacher: Grudinina Tatyana Viktorovna Lesson topic: Acids

Lesson objectives: To generalize and consolidate knowledge about the classification, nomenclature, properties of organic and inorganic acids To teach to explain the generality of the chemical properties of inorganic and organic acids To learn to correctly compose reaction equations in molecular and ionic form

Identifying Acids Acids in Nature Classifying Acids Chemical Properties of Acids Obtaining Acids Using Acids Lesson Plan:

Electrolytes are called acids, during the dissociation of which only hydrated hydrogen ions (H 3 O +) are formed as cations. 1. Determination of acids

In 1923 The protolithic theory was proposed by Bernsted-Lowry. Acids are molecules or ions that are donors of hydrogen cations H +. The H+ cation is called a proton, so the theory is called protolytic. According to the electronic theory of acids and bases by the American chemist G.N. Lewis acids are reagents that are electron acceptors.

2. Acids in nature Acid rain (nitric, sulfuric acids) Acids in food (malic, oxalic, citric, lactic, oily, coffee and others) "Chemical weapons" of animals and plants. When bitten, an ant injects poison containing formic acid. Nettle also uses it.

The pedipalpida spider shoots its enemies with a stream of acetic acid. Flat centipedes use a more terrible poison - a pair of hydrocyanic acid. Amanitas use ibotenic acid and its complex compound, muscimol. The destruction of rocks and the formation of soil. Lichens can secrete acids that can turn granite into dust.

Vitamins: ascorbic, folic, orotic, pangamic, nicotinic and others. Hyaluronic acid is the main component of joint lubrication. Amino acids form proteins. Hydrochloric acid in the stomach, it activates the enzyme pepsinogen, which decomposes food proteins, and also destroys putrefactive microflora. acids in the human body.

By composition: Oxygen-containing: H NO 3 , H 2 SO 3 ; Anoxic: HCl, H 2 S. By basicity: (the basicity of an acid is determined by the number of cations that are formed during dissociation). Monobasic: HBr, HNO 2; Dibasic: H 2 S, H 2 SO 4; Polybasic: H 3 PO 4 . Exercise. Name the acids and give them a classification: HClO 3, H 2 S, H 3 PO 4, HBr. 3. Classification of acids:

Interaction with metals located in the electrochemical series of voltages of metals up to hydrogen. 4. Chemical properties of acids: oxidizing agent, reduction reducing agent, magnesium acetate oxidation

Interaction with basic and amphoteric oxides. On one's own:

Interaction with soluble and insoluble bases. They can form medium and acidic salts. These are neutralization reactions. Alone: 1 mol (excess) 1 mol sodium hydrogen sulfate (acid salt) 1 mol 2 mol sodium sulfate (medium salt)

Interaction with salts A strong acid can displace a weak acid even from an insoluble salt. On one's own:

Hydrochloric acid For dissolving scale and rust in nickel plating, chrome plating, zinc plating, etc. steel and cast iron products For descaling steam boilers Hydrofluoric acid HF . Impregnate wood to protect against termites and other insects. Application of acids

Sulfuric acid For the production of phosphate and nitrogen fertilizers In the production of explosives Artificial fibers Dyestuffs Plastics Filling of batteries

Nitric acid Production of nitrogen fertilizers Explosives Medicinal substances Dyestuffs Plastics Man-made fibers

Task 1. Write formulas and characterize acids based on their classification: silicic acid, hydrofluoric acid. Task 2. With what substances will phosphoric acid react: K, SO 2, Na 2 SO 4, Na 2 CO 3, MgO, Ag, Ba (OH) 2. Anchoring

Task 1. H 2 SiO 3 - oxygen-containing, dibasic, insoluble, weak HF - oxygen-free, monobasic, soluble, weak Task 2. Answers

Thank you for the lesson!!!

These are substances of molecular structure. Atoms in acid molecules are connected by covalent polar bonds. The more polarized the bond between the hydrogen atom capable of splitting off and the electronegative atom (oxygen, sulfur or halogen atom), the more this bond tends to dissociate along the heterolytic path. This means that the more hydrogen cations will be in the solution and the more acidic the environment will be. Great importance has not only polarity, but also the polarizability of the bond. Polarizability is the ability of a bond to polarize under the action of certain reagents. For example, water molecules.

Acid classification

Classification of acids by the content of oxygen atoms, by the number of hydrogen atoms, by solubility and other features. See Table. 1.

*Classification features*	*Acid groups*	*Example*
*Presence of oxygen*		H 2 SO 4, HNO 3
Anoxic
*Basicity* *(number of hydrogen atoms that can be replaced by a metal)*	Monobasic
Dibasic	H 2 S, H 2 CO 3
Tribasic
*Solubility*	Soluble	H 2 SO 4, HNO 3
insoluble
*Volatility*
non-volatile
*Degree of electrolytic dissociation*		H 2 SO 4, HNO 3, HCl
	H 2 S, H 2 CO 3
*Stability*	stable	H 3 PO 4, H 2 SO 4, HCl
Unstable	H 2 CO 3 , H 2 SO 3

An example of a reaction between Lewis acids and bases.

AlCl 3 + Cl - → Cl 4 -

This interaction underlies the halogenation of aromatic compounds.

Usanovich's theory (Fig. 7). In this theory, an acid is a particle that is capable of splitting off cations or adding anions. Accordingly, the basis is vice versa. This theory is used very rarely, because it turned out to be too general. According to her, any interaction involving ions can be reduced to acid-base. And this is not very convenient.