Table of mineral acids. Names and formulas of the most important acids and salts

These are substances that dissociate in solutions to form hydrogen ions.

Acids are classified by their strength, by their basicity, and by the presence or absence of oxygen in the acid.

By strengthacids are divided into strong and weak. The most important strong acids are nitric HNO 3, sulfuric H2SO4, and hydrochloric HCl.

According to the presence of oxygen distinguish between oxygen-containing acids ( HNO3, H3PO4 etc.) and oxygen-free acids ( HCl, H 2 S, HCN, etc.).

By basicity, i.e. According to the number of hydrogen atoms in an acid molecule that can be replaced by metal atoms to form a salt, acids are divided into monobasic (for example, HNO 3, HCl), dibasic (H 2 S, H 2 SO 4), tribasic (H 3 PO 4), etc.

The names of oxygen-free acids are derived from the name of the non-metal with the addition of the ending -hydrogen: HCl - hydrochloric acid, H2S e - hydroselenic acid, HCN - hydrocyanic acid.

The names of oxygen-containing acids are also formed from the Russian name of the corresponding element with the addition of the word “acid”. In this case, the name of the acid in which the element is in the highest oxidation state ends in “naya” or “ova”, for example, H2SO4 - sulfuric acid, HClO4 - perchloric acid, H3AsO4 - arsenic acid. With a decrease in the degree of oxidation of the acid-forming element, the endings change in the following sequence: “ovate” ( HClO3 - perchloric acid), “solid” ( HClO2 - chlorous acid), “ovate” ( H O Cl - hypochlorous acid). If an element forms acids while being in only two oxidation states, then the name of the acid corresponding to the lowest oxidation state of the element receives the ending “empty” ( HNO3 - Nitric acid, HNO2 - nitrous acid).

Table - The most important acids and their salts

Obtaining acids

1. Oxygen-free acids can be obtained by direct combination of non-metals with hydrogen:

H 2 + Cl 2 → 2HCl,

H 2 + S H 2 S.

2. Oxygen-containing acids can often be obtained by directly combining acid oxides with water:

SO 3 + H 2 O = H 2 SO 4,

CO 2 + H 2 O = H 2 CO 3,

P 2 O 5 + H 2 O = 2 HPO 3.

3. Both oxygen-free and oxygen-containing acids can be obtained by exchange reactions between salts and other acids:

BaBr 2 + H 2 SO 4 = BaSO 4 + 2HBr,

CuSO 4 + H 2 S = H 2 SO 4 + CuS,

CaCO 3 + 2HBr = CaBr 2 + CO 2 + H 2 O.

4. In some cases, redox reactions can be used to produce acids:

H 2 O 2 + SO 2 = H 2 SO 4,

3P + 5HNO3 + 2H2O = 3H3PO4 + 5NO.

Chemical properties of acids

1. The most characteristic chemical property of acids is their ability to react with bases (as well as basic and amphoteric oxides) to form salts, for example:

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

2HNO 3 + FeO = Fe(NO 3) 2 + H 2 O,

2 HCl + ZnO = ZnCl 2 + H 2 O.

2. The ability to interact with some metals in the voltage series up to hydrogen, with the release of hydrogen:

Zn + 2HCl = ZnCl 2 + H 2,

2Al + 6HCl = 2AlCl3 + 3H2.

3. With salts, if a slightly soluble salt or volatile substance is formed:

H 2 SO 4 + BaCl 2 = BaSO 4 ↓ + 2HCl,

2HCl + Na 2 CO 3 = 2NaCl + H 2 O + CO 2,

2KHCO 3 + H 2 SO 4 = K 2 SO 4 +2SO 2+ 2H 2 O.

Note that polybasic acids dissociate stepwise, and the ease of dissociation at each step decreases, therefore, for polybasic acids, instead of medium salts, acidic salts are often formed (in the case of an excess of the reacting acid):

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.

4. A special case of acid-base interaction is the reaction of acids with indicators, leading to a change in color, which has long been used for the qualitative detection of acids in solutions. So, litmus changes color in an acidic environment to red.

5. When heated, oxygen-containing acids decompose into oxide and water (preferably in the presence of a water-removing agent P2O5):

H 2 SO 4 = H 2 O + SO 3,

H 2 SiO 3 = H 2 O + SiO 2.

M.V. Andryukhova, L.N. Borodina

Acids are complex substances whose molecules include hydrogen atoms that can be replaced or exchanged for metal atoms and an acid residue.

Based on the presence or absence of oxygen in the molecule, acids are divided into oxygen-containing(H 2 SO 4 sulfuric acid, H 2 SO 3 sulfurous acid, HNO 3 nitric acid, H 3 PO 4 phosphoric acid, H 2 CO 3 carbonic acid, H 2 SiO 3 silicic acid) and oxygen-free(HF hydrofluoric acid, HCl hydrochloric acid (hydrochloric acid), HBr hydrobromic acid, HI hydroiodic acid, H 2 S hydrosulfide acid).

Depending on the number of hydrogen atoms in the acid molecule, acids are monobasic (with 1 H atom), dibasic (with 2 H atoms) and tribasic (with 3 H atoms). For example, nitric acid HNO 3 is monobasic, since its molecule contains one hydrogen atom, sulfuric acid H 2 SO 4 – dibasic, etc.

There are very few inorganic compounds containing four hydrogen atoms that can be replaced by a metal.

The part of an acid molecule without hydrogen is called an acid residue.

Acidic residues may consist of one atom (-Cl, -Br, -I) - these are simple acid residues, or they may consist of a group of atoms (-SO 3, -PO 4, -SiO 3) - these are complex residues.

In aqueous solutions, during exchange and substitution reactions, acidic residues are not destroyed:

H 2 SO 4 + CuCl 2 → CuSO 4 + 2 HCl

The word anhydride means anhydrous, that is, an acid without water. For example,

H 2 SO 4 – H 2 O → SO 3. Anoxic acids do not have anhydrides.

Acids get their name from the name of the acid-forming element (acid-forming agent) with the addition of the endings “naya” and less commonly “vaya”: H 2 SO 4 – sulfuric; H 2 SO 3 – coal; H 2 SiO 3 – silicon, etc.

The element can form several oxygen acids. In this case, the indicated endings in the name of acids will be when the element exhibits a higher valence (the acid molecule contains a high content of oxygen atoms). If the element exhibits a lower valency, the ending in the name of the acid will be “empty”: HNO 3 - nitric, HNO 2 - nitrogenous.

Acids can be obtained by dissolving anhydrides in water. If the anhydrides are insoluble in water, the acid can be obtained by the action of another stronger acid on the salt of the required acid. This method is typical for both oxygen and oxygen-free acids. Oxygen-free acids are also obtained by direct synthesis from hydrogen and a non-metal, followed by dissolving the resulting compound in water:

H 2 + Cl 2 → 2 HCl;

H 2 + S → H 2 S.

Solutions of the resulting gaseous substances HCl and H 2 S are acids.

Under normal conditions, acids exist in both liquid and solid states.

Chemical properties of acids

Acid solutions act on indicators. All acids (except silicic) are highly soluble in water. Special substances - indicators allow you to determine the presence of acid.

Indicators are substances of complex structure. They change color depending on their interaction with different chemicals. In neutral solutions they have one color, in solutions of bases they have another color. When interacting with an acid, they change their color: the methyl orange indicator turns red, and the litmus indicator also turns red.

Interact with bases with the formation of water and salt, which contains an unchanged acid residue (neutralization reaction):

H 2 SO 4 + Ca(OH) 2 → CaSO 4 + 2 H 2 O.

Interact with base oxides with the formation of water and salt (neutralization reaction). The salt contains the acid residue of the acid that was used in the neutralization reaction:

H 3 PO 4 + Fe 2 O 3 → 2 FePO 4 + 3 H 2 O.

Interact with metals. For acids to interact with metals, certain conditions must be met:

1. the metal must be sufficiently active with respect to acids (in the series of activity of metals it must be located before hydrogen). The further to the left a metal is in the activity series, the more intensely it interacts with acids;

2. the acid must be strong enough (that is, capable of donating hydrogen ions H +).

When chemical reactions of acid with metals occur, salt is formed and hydrogen is released (except for the interaction of metals with nitric and concentrated sulfuric acids):

Zn + 2HCl → ZnCl 2 + H 2 ;

Cu + 4HNO 3 → CuNO 3 + 2 NO 2 + 2 H 2 O.

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Acids- complex substances consisting of one or more hydrogen atoms that can be replaced by metal atoms and acidic residues.

Classification of acids

1. By the number of hydrogen atoms: number of hydrogen atoms ( n ) determines the basicity of acids:

n= 1 monobase

n= 2 dibase

n= 3 tribase

2. By composition:

a) Table of oxygen-containing acids, acid residues and corresponding acid oxides:

b) Table of oxygen-free acids

Physical properties of acids

Many acids, such as sulfuric, nitric, and hydrochloric, are colorless liquids. solid acids are also known: orthophosphoric, metaphosphoric HPO 3, boric H 3 BO 3 . Almost all acids are soluble in water. An example of an insoluble acid is silicic acid H2SiO3 . Acid solutions have a sour taste. For example, many fruits are given a sour taste by the acids they contain. Hence the names of acids: citric, malic, etc.

Methods for producing acids

Chemical properties of acids

1. Change the color of the indicators

2. React with metals in the activity series up to H 2

(excl. HNO 3 -Nitric acid)

Video "Interaction of acids with metals"

Me + ACID = SALT + H 2 (r. substitution)

Zn + 2 HCl = ZnCl 2 + H 2

3. With basic (amphoteric) oxides – metal oxides

Video "Interaction of metal oxides with acids"

Fur x O y + ACID = SALT + H 2 O (exchange ruble)

4. React with bases – neutralization reaction

ACID + BASE= SALT+ H 2 O (exchange ruble)

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

5. React with salts of weak, volatile acids - if acid forms, precipitates or gas evolves:

2 NaCl (tv.) + H 2 SO 4 (conc.) = Na 2 SO 4 + 2HCl ( R . exchange )

Video "Interaction of acids with salts"

6. Decomposition of oxygen-containing acids when heated

(excl. H 2 SO 4 ; H 3 P.O. 4 )

ACID = ACID OXIDE + WATER (r. expansion)

Remember!Unstable acids (carbonic and sulfurous acids) - decompose into gas and water:

H 2 CO 3 ↔ H 2 O + CO 2

H 2 SO 3 ↔ H 2 O + SO 2

Hydrogen sulfide acid in products released as gas:

CaS + 2HCl = H 2 S+CaCl2

ASSIGNMENT TASKS

No. 1. Distribute the chemical formulas of acids in a table. Give them names:

LiOH, Mn 2 O 7, CaO, Na 3 PO 4, H 2 S, MnO, Fe (OH) 3, Cr 2 O 3, HI, HClO 4, HBr, CaCl 2, Na 2 O, HCl, H 2 SO 4, HNO 3, HMnO 4, Ca (OH) 2, SiO 2, Acids

Bes-sour-

native

Oxygen-containing

soluble

insoluble

one-

basic

two-basic

three-basic

No. 2. Write down the reaction equations:

Ca+HCl

Na+H2SO4

Al+H2S

Ca+H3PO4
Name the reaction products.

No. 3. Write down reaction equations and name the products:

Na 2 O + H 2 CO 3

ZnO + HCl

CaO + HNO3

Fe 2 O 3 + H 2 SO 4

No. 4. Write down equations for the reactions of acids with bases and salts:

KOH + HNO3

NaOH + H2SO3

Ca(OH) 2 + H 2 S

Al(OH) 3 + HF

HCl + Na 2 SiO 3

H2SO4 + K2CO3

HNO3 + CaCO3

Name the reaction products.

EXERCISES

Trainer No. 1. "Formula and names of acids"

Trainer No. 2. "Establishing correspondence: acid formula - oxide formula"

Safety precautions - First aid if acids come into contact with skin

Safety precautions -

End adj.

Prefixes most often used in names

Interpolation of reference values

Sometimes it is necessary to obtain a density or concentration value that is not indicated in the reference tables. The required parameter can be found by interpolation.

Example

To prepare the HCl solution, the acid available in the laboratory was taken, the density of which was determined by a hydrometer. It turned out to be equal to 1.082 g/cm3.

According to the reference table, we find that an acid with a density of 1.080 has a mass fraction of 16.74%, and with 1.085 - 17.45%. To find the mass fraction of acid in an existing solution, we use the interpolation formula:

%,

where is the index 1 refers to a more dilute solution, and 2 - to more concentrated.

Preface……………………………..………….……….…......3

1. Basic concepts of titrimetric methods of analysis......7

2. Titration methods and methods……………………….....……...9

3. Calculation of molar mass of equivalents.………………16

4. Methods of expressing the quantitative composition of solutions

in titrimetry……………………………………………………..21

4.1. Solving typical problems on methods of expression

quantitative composition of solutions……………….……25

4.1.1. Calculation of the concentration of a solution based on the known mass and volume of the solution………………………………………………………..26

4.1.1.1. Problems for independent solution...29

4.1.2. Conversion of one concentration to another………...30

4.1.2.1. Problems for independent solution...34

5. Methods for preparing solutions…………………………...36

5.1. Solving typical problems for preparing solutions

in various ways…………………………………..39

5.2. Problems for independent solution………………….48

6. Calculation of titrimetric analysis results……….........51

6.1. Calculation of direct and substitution results

titration…………………………………………………………...51

6.2. Calculation of back titration results……………...56

7. Neutralization method (acid-base titration)……59

7.1. Examples of solving typical problems……………………..68

7.1.1. Direct and substitution titration……………68

7.1.1.1. Problems for independent solution...73

7.1.2. Back titration……………………………..76

7.1.2.1. Problems for independent solution...77

8. Oxidation-reduction method (redoximetry)………...80

8.1. Problems for independent solution………………….89

8.1.1. Redox reactions……..89

8.1.2. Calculation of titration results…………………...90

8.1.2.1. Substitution titration……………...90

8.1.2.2. Forward and reverse titration…………..92

9. Complexation method; complexometry…........94

9.1. Examples of solving typical problems……………………...102

9.2. Problems for independent solution………………...104

10. Deposition method………………………………………........106

10.1. Examples of solving typical problems…………………….110

10.2. Problems for independent solution……………….114

11. Individual tasks on titrimetric

methods of analysis……………………………………………………………117

11.1. Plan for completing an individual task………...117

11.2. Options for individual tasks………………….123

Answers to problems………..……………………………………………………124

Symbols…………………………………………………….…127

Appendix……………………………………………………...128

EDUCATIONAL EDITION

ANALYTICAL CHEMISTRY

Acids are chemical compounds that are capable of donating an electrically charged hydrogen ion (cation) and also accepting two interacting electrons, resulting in the formation of a covalent bond.

In this article we will look at the main acids that are studied in middle grades of secondary schools, and also learn many interesting facts about a wide variety of acids. Let's get started.

Acids: types

In chemistry, there are many different acids that have very different properties. Chemists distinguish acids by their oxygen content, volatility, solubility in water, strength, stability, and whether they belong to the 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 names and formulas much faster.

Hydrogen sulfide 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. Hydrogen sulfide 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 also a very strong rotten egg smell. 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 an acid is indispensable in industry, it can be very harmful to human health. This acid is very toxic to humans. When a small amount of hydrogen sulfide is inhaled, a person experiences a headache, severe nausea and dizziness. If a person inhales a large amount 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, which children are introduced to in chemistry lessons in the 8th grade. Chemical acids such as sulfuric acid 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 when it comes into contact with skin or clothing, but it 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 a well-known nitric acid. It has found wide application in industry as well as in agriculture. It is used to make various fertilizers, in jewelry, in photograph printing, 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. HNO 3 vapors 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 acid formula is HF. Hydrofluoric acid is very actively used in the aluminum industry. It is used to dissolve silicates, etch silicon and silicate glass.

Hydrogen fluoride is very harmful to the human body and, depending on its concentration, can be a mild narcotic. If it comes into contact with the skin, at first there are no changes, but after a few minutes a sharp pain and 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. The acid is transparent and colorless in appearance, but smokes in air. Hydrogen chloride is widely used in the metallurgical and food industries.

This acid causes chemical burns, but getting into the eyes is especially dangerous.

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 restore iron from rust. In addition, phosphoric (or orthophosphoric) acid is widely used in agriculture - many different 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 chipping of teeth.

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. By knowing the density, you can determine the concentration of a particular acid, solve chemical calculation problems, and add the correct amount of acid to complete the reaction. The density of any acid changes depending on the concentration. For example, the higher the concentration percentage, the higher the density.

General properties of acids

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

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

Acids differ sharply from each other in their physical properties. After all, they can have a smell or not, and also be in a variety of physical states: liquid, gaseous and even solid. Solid acids are very interesting to study. Examples of such acids: C 2 H 2 0 4 and H 3 BO 3.

Concentration

Concentration is a value that determines the quantitative composition of any solution. For example, chemists often need to determine how much pure sulfuric acid is present in dilute acid H 2 SO 4. To do this, they pour a small amount of dilute acid into a measuring cup, weigh it, and determine the concentration using a density chart. The concentration of acids is closely related to density; often, when determining the concentration, there are calculation problems where you need to determine the percentage of pure acid in a 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 they contain only one H atom. There are many such acids, it is impossible to remember absolutely every one. You just need to remember that acids are also classified according to 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 oxygen-free. How to remember, without knowing the chemical formula of a substance, that it is an oxygen-containing acid?

All oxygen-free acids lack the important element O - oxygen, but they do contain H. Therefore, the word “hydrogen” is always attached to their name. HCl is a H 2 S - hydrogen sulfide.

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

• H 2 SO 4 - sulfur (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 that we will now consider.

There are substances called indicators. The indicators change their color, or the color remains, but its shade changes. This occurs when the indicators are affected by other substances, such as acids.

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

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

When the tensions are in the tension series before hydrogen, 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 and no gas will be released. 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.