9 basic acids in chemistry. inorganic acids

Names of some inorganic acids and salts

Let me briefly remind you with specific examples of how salts should be properly named.

Example 1. Salt K 2 SO 4 is formed by the rest of sulfuric acid (SO 4) and metal K. Salts of sulfuric acid are called sulfates. K 2 SO 4 - potassium sulfate.

Example 2. FeCl 3 - the composition of the salt includes iron and the rest of hydrochloric acid (Cl). Name of the salt: iron(III) chloride. Please note: in this case, we not only have to name the metal, but also indicate its valency (III). In the previous example, this was not necessary, since the valency of sodium is constant.

Important: in the name of the salt, the valency of the metal should be indicated only if this metal has a variable valency!

Example 3. Ba (ClO) 2 - the composition of the salt includes barium and the remainder of hypochlorous acid (ClO). Name of salt: barium hypochlorite. The valency of the Ba metal in all its compounds is two, it is not necessary to indicate it.

Example 4. (NH 4) 2 Cr 2 O 7. The NH 4 group is called ammonium, the valence of this group is constant. Salt name: ammonium dichromate (bichromate).

In the above examples, we met only the so-called. medium or normal salts. Acid, basic, double and complex salts, salts of organic acids will not be discussed here.

Let me briefly remind you with specific examples of how salts should be properly named.

Example 1. Salt K 2 SO 4 is formed by the rest of sulfuric acid (SO 4) and metal K. Salts of sulfuric acid are called sulfates. K 2 SO 4 - potassium sulfate.

Example 2. FeCl 3 - the composition of the salt includes iron and the rest of hydrochloric acid (Cl). Name of the salt: iron(III) chloride. Please note: in this case, we not only have to name the metal, but also indicate its valency (III). In the previous example, this was not necessary, since the valency of sodium is constant.

Important: in the name of the salt, the valency of the metal should be indicated only if this metal has a variable valency!

Example 3. Ba (ClO) 2 - the composition of the salt includes barium and the remainder of hypochlorous acid (ClO). Name of salt: barium hypochlorite. The valency of the Ba metal in all its compounds is two, it is not necessary to indicate it.

Example 4. (NH 4) 2 Cr 2 O 7. The NH 4 group is called ammonium, the valence of this group is constant. Salt name: ammonium dichromate (bichromate).

In the above examples, we met only the so-called. medium or normal salts. Acid, basic, double and complex salts, salts of organic acids will not be discussed here.

If you are interested not only in the nomenclature of salts, but also in the methods for their preparation and chemical properties, I recommend that you refer to the relevant sections of the reference book on chemistry: "

Consider the most common formulas of acids in the educational literature:

It is easy to see what unites all the formulas of acids is the presence of hydrogen atoms (H), which comes first in the formula.

Determination of the valency of the acid residue

From the above list, it can be seen that the number of these atoms may differ. Acids, which contain only one hydrogen atom, are called monobasic (nitric, hydrochloric, and others). Sulfuric, carbonic, silicic acids are dibasic, since their formulas contain two H atoms each. A tribasic phosphoric acid molecule contains three hydrogen atoms.

Thus, the amount of H in the formula characterizes the basicity of the acid.

That atom, or group of atoms, which are written after hydrogen, is called acid residues. For example, in hydrosulfide acid, the residue consists of one atom - S, and in phosphoric, sulfuric and many others - of two, and one of them is necessarily oxygen (O). On this basis, all acids are divided into oxygen-containing and anoxic.

Each acid residue has a certain valence. It is equal to the number of H atoms in the molecule of this acid. The valency of the HCl residue is equal to one, since it is a monobasic acid. The residues of nitric, perchloric, and nitrous acids have the same valency. The valency of the sulfuric acid residue (SO 4) is two, since there are two hydrogen atoms in its formula. A trivalent phosphoric acid residue.

Acid residues - anions

In addition to valency, acid residues have charges and are anions. Their charges are listed in the solubility table: CO 3 2− , S 2− , Cl − and so on. Please note: the charge of the acid residue numerically coincides with its valency. For example, in silicic acid, the formula of which is H 2 SiO 3, the acid residue SiO 3 has a valence equal to II and a charge of 2-. Thus, knowing the charge of the acid residue, it is easy to determine its valency and vice versa.

Summarize. Acids are compounds formed by hydrogen atoms and acid residues. From the point of view of the theory of electrolytic dissociation, another definition can be given: acids are electrolytes, in solutions and melts of which there are hydrogen cations and anions of acid residues.

Hints

The chemical formulas of acids, as a rule, are memorized, as are their names. If you have forgotten how many hydrogen atoms are in a particular formula, but you know what its acidic residue looks like, a solubility table will come to your aid. The charge of the residue coincides in absolute value with the valence, and that with the amount of H. For example, you remember that the residue of carbonic acid is CO 3. According to the solubility table, you determine that its charge is 2-, which means that it is divalent, that is, carbonic acid has the formula H 2 CO 3.

Often there is confusion with the formulas of sulfuric and sulphurous, as well as nitric and nitrous acids. Here, too, there is one point that makes it easier to remember: the name of the acid from the pair in which there are more oxygen atoms ends in -naya (sulfuric, nitric). An acid with fewer oxygen atoms in the formula has a name ending in -ista (sulphurous, nitrogenous).

However, these tips will only help if you are familiar with the acid formulas. Let's repeat them again.

acids- complex substances consisting of one or more hydrogen atoms capable of being replaced by metal atoms, and acidic residues.

Acid classification

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

n= 1 single base

n= 2 dibasic

n= 3 tribasic

2. By composition:

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

b) Table of anoxic acids

Physical properties of acids

Many acids, such as sulfuric, nitric, 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 H2SiO3 . Acid solutions have a sour taste. So, for example, many fruits give a sour taste to the acids they contain. Hence the names of acids: citric, malic, etc.

Methods for obtaining 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 \u003d SALT + H 2 (p. substitution)

Zn + 2 HCl \u003d ZnCl 2 + H 2

3. With basic (amphoteric) oxides – metal oxides

Video "Interaction of metal oxides with acids"

Me x O y + ACID \u003d SALT + H 2 O (p. exchange)

4. React with bases – neutralization reaction

ACID + BASE = SALT + H 2 O (p. exchange)

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

5. React with salts of weak, volatile acids - if an acid is formed that precipitates or a gas is released:

2 NaCl (tv.) + H 2 SO 4 (conc.) \u003d 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 PO 4 )

ACID = ACID OXIDE + WATER (r. decomposition)

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

H 2 CO 3 ↔ H 2 O + CO 2

H 2 SO 3 ↔ H 2 O + SO 2

Hydrosulphuric acid in products released as a gas:

CaS + 2HCl \u003d H 2 S+ CaCl2

TASKS FOR REINFORCEMENT

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-

main

two-core

tri-basic

No. 2. Write reaction equations:

Ca+HCl

Na + H 2 SO 4

Al + H 2 S

Ca + H 3 PO 4
Name the reaction products.

No. 3. Make the reaction equations, name the products:

Na 2 O + H 2 CO 3

ZnO + HCl

CaO + HNO3

Fe 2 O 3 + H 2 SO 4

No. 4. Make up the reaction equations for the interaction 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

H 2 SO 4 + K 2 CO 3

HNO 3 + CaCO 3

Name the reaction products.

SIMULATORS

Trainer number 1. "Formulas and names of acids"

Trainer number 2. "Correspondence: acid formula - oxide formula"

Safety Precautions - First Aid for Skin Contact with Acids

Safety -

Substances that dissociate in solutions to form hydrogen ions are called.

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

By strengthacids are divided into strong and weak. The most important strong acids are nitric HNO 3 , sulfuric H 2 SO 4 , and hydrochloric HCl .

By the presence of oxygen distinguish oxygen-containing acids ( HNO3, H3PO4 etc.) and anoxic 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, H 2 S 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". At the same time, 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, HClO 4 - perchloric acid, H 3 AsO 4 - arsenic acid. With a decrease in the degree of oxidation of the acid-forming element, the endings change in the following sequence: “oval” ( HClO 3 - chloric acid), "pure" ( HClO 2 - chlorous acid), "wobbly" ( H O Cl - hypochlorous acid). If the element forms acids, being in only two oxidation states, then the name of the acid corresponding to the lowest oxidation state of the element receives the ending "pure" ( HNO3 - Nitric acid, HNO 2 - nitrous acid).

Table - The most important acids and their salts

Obtaining acids

1. Anoxic 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 \u003d H 2 SO 4,

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

P 2 O 5 + H 2 O \u003d 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 \u003d BaSO 4 + 2HBr,

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

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

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

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

3P + 5HNO 3 + 2H 2 O = 3H 3 PO 4 + 5NO.

Chemical properties of acids

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

H 2 SO 4 + 2NaOH \u003d Na 2 SO 4 + 2H 2 O,

2HNO 3 + FeO \u003d Fe (NO 3) 2 + H 2 O,

2 HCl + ZnO \u003d ZnCl 2 + H 2 O.

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

Zn + 2HCl \u003d ZnCl 2 + H 2,

2Al + 6HCl \u003d 2AlCl 3 + 3H 2.

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

H 2 SO 4 + BaCl 2 = BaSO 4 ↓ + 2HCl,

2HCl + Na 2 CO 3 \u003d 2NaCl + H 2 O + CO 2,

2KHCO 3 + H 2 SO 4 \u003d K 2 SO 4 + 2SO 2+ 2H2O.

Note that polybasic acids dissociate in steps, and the ease of dissociation in each of the steps decreases, therefore, for polybasic acids, acid salts are often formed instead of medium salts (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 P2O5):

H 2 SO 4 \u003d H 2 O + SO 3,

H 2 SiO 3 \u003d H 2 O + SiO 2.

M.V. Andryukhova, L.N. Borodin