Chemical properties of salts table with examples. Chemical properties of salts

Grounds

Bases are compounds containing only hydroxide ions OH - as an anion. The number of hydroxide ions that can be replaced by an acidic residue determines the acidity of the base. In this regard, bases are one-, two- and polyacid; however, true bases most often include one- and two-acid. Among them, water-soluble and water-insoluble bases should be distinguished. Please note that bases that are soluble in water and dissociate almost completely are called alkalis (strong electrolytes). These include hydroxides of alkali and alkaline earth elements and in no case a solution of ammonia in water.

The name of the base begins with the word hydroxide, after which the Russian name of the cation is given in the genitive case, and its charge is indicated in parentheses. It is allowed to list the number of hydroxide ions using the prefixes di-, tri-, tetra. For example: Mn(OH) 3 - manganese (III) hydroxide or manganese trihydroxide.

Note that there is a genetic relationship between bases and basic oxides: basic oxides correspond to bases. Therefore, base cations most often have a charge of one or two, which corresponds to the lowest oxidation states of metals.

Remember the basic ways to obtain bases

1. Interaction of active metals with water:

2Na + 2H 2 O = 2NaOH + H 2

La + 6H 2 O = 2La(OH) 3 + 3H 2

Interaction of basic oxides with water:

CaO + H 2 O = Ca(OH) 2

MgO + H 2 O = Mg(OH) 2.

3. Interaction of salts with alkalis:

MnSO 4 + 2KOH = Mn(OH) 2 ↓ + K 2 SO 4

NH 4 С1 + NaOH = NaCl + NH 3 ∙ H 2 O

Na 2 CO 3 + Ca(OH) 2 = 2NaOH + CaCO 3

MgOHCl + NaOH = Mg(OH) 2 + NaCl.

Electrolysis of aqueous salt solutions with a diaphragm:

2NaCl + 2H 2 O → 2NaOH + Cl 2 + H 2

Please note that in step 3, the starting reagents must be selected in such a way that among the reaction products there is either a sparingly soluble compound or a weak electrolyte.

Note that when considering the chemical properties of bases, reaction conditions depend on the solubility of the base.

1. Interaction with acids:

NaOH + H 2 SO 4 = NaHSO 4 + H 2 O

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

2Mg(OH) 2 + H 2 SO 4 = (MgOH) 2 SO 4 + 2H 2 O

Mg(OH) 2 + H 2 SO 4 = MgSO 4 + 2H 2 O

Mg(OH) 2 + 2H 2 SO 4 = Mg(HSO 4) 2 + 2H 2 O

2. Interaction with acid oxides:

NaOH + CO 2 = NaHCO 3

2NaOH + CO 2 = Na 2 CO 3 + H 2 O

Fe(OH) 2 + P 2 O 5 = Fe(PO 3) 2 + H 2 O

3Fe(OH) 2 + P 2 O 5 = Fe 3 (PO 4) 2 + 2H 2 O

3. Interaction with amphoteric oxides:

A1 2 O 3 + 2NaOH p + 3H 2 O = 2Na

Al 2 O 3 + 2NaOH T = 2NaAlO 2 + H 2 O

Cr 2 O 3 + Mg(OH) 2 = Mg(CrO 2) 2 + H 2 O

4. Interaction with ampheteric hydroxides:

Ca(OH) 2 + 2Al(OH) 3 = Ca(AlO 2) 2 + 4H 2 O

3NaOH + Cr(OH) 3 = Na 3

Interaction with salts.

To the reactions described in point 3 of the production methods, the following should be added:

2ZnSO 4 + 2KOH = (ZnOH) 2 S0 4 + K 2 SO 4

NaHCO 3 + NaOH = Na 2 CO 3 + H 2 O

BeSO 4 + 4NaOH = Na 2 + Na 2 SO 4

Cu(OH) 2 + 4NH 3 ∙H 2 O = (OH) 2 + 4H 2 O

6. Oxidation to amphoteric hydroxides or salts:

4Fe(OH) 2 + O 2 + 2H 2 O = 4Fe(OH) 3

2Cr(OH) 2 + 2H 2 O + Na 2 O 2 + 4NaOH = 2Na 3.

7. Heat decomposition:

Ca(OH) 2 = CaO + H 2 O.

Please note that alkali metal hydroxides, except lithium, do not participate in such reactions.

!!!Are there alkaline precipitations?!!! Yes, there are, but they are not as widespread as acid precipitation, are little known, and their impact on environmental objects has been practically unstudied. Nevertheless, their consideration deserves attention.

The origin of alkaline precipitation can be explained as follows.

CaCO 3 →CaO + CO 2

In the atmosphere, calcium oxide combines with water vapor during condensation, with rain or sleet, forming calcium hydroxide:

CaO + H 2 O →Ca(OH) 2,

which creates an alkaline reaction of atmospheric precipitation. In the future, it is possible to react calcium hydroxide with carbon dioxide and water to form calcium carbonate and calcium bicarbonate:

Ca(OH) 2 + CO 2 → CaCO 3 + H 2 O;

CaCO 3 + CO 2 + H 2 O → Ca(HC0 3) 2.

Chemical analysis of rainwater showed that it contains sulfate and nitrate ions in small quantities (about 0.2 mg/l). As is known, the cause of the acidic nature of precipitation is sulfuric and nitric acids. At the same time, there is a high content of calcium cations (5-8 mg/l) and bicarbonate ions, the content of which in the area of ​​​​the construction complex enterprises is 1.5-2 times higher than in other areas of the city, and amounts to 18-24 mg /l. This shows that the calcium carbonate system and the processes occurring in it play a major role in the formation of local alkaline sediments, as mentioned above.

Alkaline precipitation affects plants; changes in the phenotypic structure of plants are noted. There are traces of “burns” on the leaf blades, a white coating on the leaves and a depressed state of herbaceous plants.

Which consist of an anion (acid residue) and a cation (metal atom). In most cases, these are crystalline substances of various colors and with different solubility in water. The simplest representative of this class of compounds is (NaCl).

Salts are divided into acidic, normal and basic.

Normal (medium) are formed in cases when all hydrogen atoms in an acid are replaced by metal atoms or when all hydroxyl groups of the base are replaced by acidic residues of acids (for example, MgSO4, Mg (CH3COO) 2). During electrolytic dissociation, they decompose into positively charged metal anions and negatively charged acidic residues.

Chemical properties of salts of this group:

Decomposes when exposed to high temperatures;

Are subject to hydrolysis (interaction with water);

They enter into exchange reactions with acids, other salts and bases. It is worth remembering some features of these reactions:

A reaction with an acid takes place only when it is different from the one from which the salt comes;

A reaction with a base occurs when an insoluble substance is formed;

A saline solution reacts with a metal if it is in the electrochemical voltage series to the left of the metal that is part of the salt;

Salt compounds in solutions interact with each other if an insoluble metabolic product is formed;

Redox, which can be associated with the properties of a cation or anion.

Acid salts are obtained in cases where only part of the hydrogen atoms in the acid are replaced by metal atoms (for example, NaHSO4, CaHPO4). During electrolytic dissociation, they form hydrogen and metal cations, anions of the acid residue, therefore the chemical properties of salts of this group include the following characteristics of both salt and acid compounds:

Subject to thermal decomposition with the formation of medium salt;

React with alkali to form normal salt.

Basic salts are obtained in cases where only part of the hydroxyl groups of the bases is replaced by acidic residues of acids (for example, Cu (OH) or Cl, Fe (OH) CO3). Such compounds dissociate into metal cations and hydroxyl and acid anions. The chemical properties of salts of this group include characteristic chemical characteristics of both salt substances and bases at the same time:

Characterized by thermal decomposition;

Interact with acid.

There is also the concept of complex and

Complex ones contain a complex anion or cation. The chemical properties of salts of this type include reactions of destruction of complexes, accompanied by the formation of poorly soluble compounds. In addition, they are capable of exchanging ligands between the inner and outer spheres.

Double ones have two different cations and can react with alkali solutions (reduction reaction).

Methods for obtaining salts

These substances can be obtained in the following ways:

The interaction of acids with metals that are capable of displacing hydrogen atoms;

In the reaction of bases and acids, when the hydroxyl groups of the bases are exchanged with the acidic residues of the acids;

The action of acids on amphoteric and salts or metals;

The action of bases on acid oxides;

Reaction between acidic and basic oxides;

The interaction of salts with each other or with metals;

Obtaining salts from reactions of metals with non-metals;

Acidic salt compounds are obtained by reacting an average salt with an acid of the same name;

Basic salt substances are obtained by reacting salt with a small amount of alkali.

So, salts can be obtained in many ways, since they are formed as a result of many chemical reactions between various inorganic substances and compounds.

Salts are the product of replacing hydrogen atoms in an acid with a metal. Soluble salts in soda dissociate into a metal cation and an acid residue anion. Salts are divided into:

· Average

· Basic

· Complex

· Double

· Mixed

Medium salts. These are products of complete replacement of hydrogen atoms in an acid with metal atoms, or with a group of atoms (NH 4 +): MgSO 4, Na 2 SO 4, NH 4 Cl, Al 2 (SO 4) 3.

The names of medium salts come from the names of metals and acids: CuSO 4 - copper sulfate, Na 3 PO 4 - sodium phosphate, NaNO 2 - sodium nitrite, NaClO - sodium hypochlorite, NaClO 2 - sodium chlorite, NaClO 3 - sodium chlorate, NaClO 4 - sodium perchlorate, CuI - copper(I) iodide, CaF 2 - calcium fluoride. You also need to remember a few trivial names: NaCl - table salt, KNO3 - potassium nitrate, K2CO3 - potash, Na2CO3 - soda ash, Na2CO3∙10H2O - crystalline soda, CuSO4 - copper sulfate, Na 2 B 4 O 7 . 10H 2 O - borax, Na 2 SO 4 . 10H 2 O-Glauber's salt. Double salts. This salt , containing two types of cations (hydrogen atoms polybasic acids are replaced by two different cations): MgNH 4 PO 4, KAl (SO 4) 2, NaKSO 4 .Double salts as individual compounds exist only in crystalline form. When dissolved in water they are completelydissociate into metal ions and acidic residues (if the salts are soluble), for example:

NaKSO 4 ↔ Na + + K + + SO 4 2-

It is noteworthy that the dissociation of double salts in aqueous solutions occurs in 1 step. To name salts of this type, you need to know the names of the anion and two cations: MgNH4PO4 - magnesium ammonium phosphate.

Complex salts.These are particles (neutral molecules orions ), which are formed as a result of joining to a given ion (or atom ), called complexing agent, neutral molecules or other ions called ligands. Complex salts are divided into:

1) Cationic complexes

Cl 2 - tetraammine zinc(II) dichloride
Cl2- di hexaammine cobalt(II) chloride

2) Anion complexes

K 2 - potassium tetrafluoroberyllate(II)
Li-lithium tetrahydridealuminate(III)
K 3 -potassium hexacyanoferrate(III)

The theory of the structure of complex compounds was developed by the Swiss chemist A. Werner.

Acid salts– products of incomplete replacement of hydrogen atoms in polybasic acids with metal cations.

For example: NaHCO 3

Chemical properties:
React with metals located in the voltage series to the left of hydrogen.
2KHSO 4 +Mg→H 2 +Mg(SO) 4 +K 2 (SO) 4

Note that for such reactions it is dangerous to take alkali metals, because they will first react with water with a large release of energy, and an explosion will occur, since all reactions occur in solutions.

2NaHCO 3 +Fe→H 2 +Na 2 CO 3 +Fe 2 (CO 3) 3 ↓

Acid salts react with alkali solutions and form medium salt(s) and water:

NaHCO 3 +NaOH→Na 2 CO 3 +H 2 O

2KHSO 4 +2NaOH→2H 2 O+K 2 SO 4 +Na 2 SO 4

Acid salts react with solutions of medium salts if gas is released, a precipitate forms, or water is released:

2KHSO 4 +MgCO 3 →MgSO 4 +K 2 SO 4 +CO 2 +H 2 O

2KHSO 4 +BaCl 2 →BaSO 4 ↓+K 2 SO 4 +2HCl

Acid salts react with acids if the acid product of the reaction is weaker or more volatile than the one added.

NaHCO 3 +HCl→NaCl+CO 2 +H 2 O

Acid salts react with basic oxides to release water and medium salts:

2NaHCO 3 +MgO→MgCO 3 ↓+Na 2 CO 3 +H 2 O

2KHSO 4 +BeO→BeSO 4 +K 2 SO 4 +H 2 O

Acid salts (in particular bicarbonates) decompose under the influence of temperature:
2NaHCO 3 → Na 2 CO 3 +CO 2 +H 2 O

Receipt:

Acid salts are formed when an alkali is exposed to an excess solution of a polybasic acid (neutralization reaction):

NaOH+H 2 SO 4 →NaHSO 4 +H 2 O

Mg(OH) 2 +2H 2 SO 4 →Mg(HSO 4) 2 +2H 2 O

Acid salts are formed by dissolving basic oxides in polybasic acids:
MgO+2H 2 SO 4 →Mg(HSO 4) 2 +H 2 O

Acid salts are formed when metals are dissolved in an excess solution of a polybasic acid:
Mg+2H 2 SO 4 →Mg(HSO 4) 2 +H 2

Acidic salts are formed as a result of the interaction of the average salt and the acid that forms the average salt anion:
Ca 3 (PO 4) 2 +H 3 PO 4 →3CaHPO 4

Basic salts:

Basic salts are a product of incomplete replacement of the hydroxo group in the molecules of polyacid bases with acidic residues.

Example: MgOHNO 3,FeOHCl.

Chemical properties:
Basic salts react with excess acid to form a medium salt and water.

MgOHNO 3 +HNO 3 →Mg(NO 3) 2 +H 2 O

Basic salts are decomposed by temperature:

2 CO 3 →2CuO+CO 2 +H 2 O

Preparation of basic salts:
Interaction of salts of weak acids with medium salts:
2MgCl 2 +2Na 2 CO 3 +H 2 O→ 2 CO 3 +CO 2 +4NaCl
Hydrolysis of salts formed by a weak base and a strong acid:

ZnCl 2 +H 2 O→Cl+HCl

Most basic salts are slightly soluble. Many of them are minerals, e.g. malachite Cu 2 CO 3 (OH) 2 and hydroxyapatite Ca 5 (PO 4) 3 OH.

The properties of mixed salts are not covered in a school chemistry course, but the definition is important to know.
Mixed salts are salts in which the acid residues of two different acids are attached to one metal cation.

A good example is Ca(OCl)Cl bleaching lime (bleach).

Nomenclature:

1. Salt contains a complex cation

First, the cation is named, then the ligands included in the inner sphere are the anions, ending in “o” ( Cl - - chloro, OH - -hydroxy), then ligands, which are neutral molecules ( NH 3 -amine, H 2 O -aquo).If there are more than 1 identical ligands, their number is denoted by Greek numerals: 1 - mono, 2 - di, 3 - three, 4 - tetra, 5 - penta, 6 - hexa, 7 - hepta, 8 - octa, 9 - nona, 10 - deca. The latter is called the complexing ion, indicating its valence in parentheses if it is variable.

[Ag (NH 3 ) 2 ](OH )-silver diamine hydroxide ( I)

[Co (NH 3 ) 4 Cl 2 ] Cl 2 -chloride dichloro o cobalt tetraamine ( III)

2. The salt contains a complex anion.

First, the ligands - anions - are named, then the neutral molecules entering the inner sphere ending in “o” are named, indicating their number with Greek numerals. The latter is called a complexing ion in Latin, with the suffix “at”, indicating the valency in brackets. Next, the name of the cation located in the outer sphere is written; the number of cations is not indicated.

Potassium K 4 -hexacyanoferrate (II) (reagent for Fe 3+ ions)

K 3 - potassium hexacyanoferrate (III) (reagent for Fe 2+ ions)

Na 2 -sodium tetrahydroxozincate

Most complexing ions are metals. The d elements exhibit the greatest tendency to complex formation. Around the central complexing ion are oppositely charged ions or neutral molecules - ligands or addends.

The complexing ion and ligands make up the inner sphere of the complex (in square brackets); the number of ligands coordinated around the central ion is called the coordination number.

The ions that do not enter the inner sphere form the outer sphere. If the complex ion is a cation, then there are anions in the outer sphere and vice versa, if the complex ion is an anion, then there are cations in the outer sphere. The cations are usually ions of alkali and alkaline earth metals, ammonium cation. When dissociated, complex compounds give complex complex ions that are quite stable in solutions:

K 3 ↔3K + + 3-

If we are talking about acidic salts, then when reading the formula the prefix hydro- is pronounced, for example:
Sodium hydrosulfide NaHS

Sodium bicarbonate NaHCO 3

With basic salts the prefix is ​​used hydroxo- or dihydroxo-

(depends on the oxidation state of the metal in the salt), for example:
magnesium hydroxychlorideMg(OH)Cl, aluminum dihydroxychloride Al(OH) 2 Cl

Methods for obtaining salts:

1. Direct interaction of metal with non-metal . This method can be used to obtain salts of oxygen-free acids.

Zn+Cl 2 →ZnCl 2

2. Reaction between acid and base (neutralization reaction). Reactions of this type are of great practical importance (qualitative reactions to most cations); they are always accompanied by the release of water:

NaOH+HCl→NaCl+H 2 O

Ba(OH) 2 +H 2 SO 4 →BaSO 4 ↓+2H 2 O

3. Interaction of a basic oxide with an acidic one :

SO 3 +BaO→BaSO 4 ↓

4. Reaction between acid oxide and base :

2NaOH+2NO 2 →NaNO 3 +NaNO 2 +H 2 O

NaOH+CO 2 →Na 2 CO 3 +H 2 O

5. Reaction between basic oxide and acid :

Na 2 O+2HCl→2NaCl+H 2 O

CuO+2HNO 3 =Cu(NO 3) 2 +H 2 O

6. Direct interaction of metal with acid. This reaction may be accompanied by the evolution of hydrogen. Whether hydrogen will be released or not depends on the activity of the metal, the chemical properties of the acid and its concentration (see Properties of concentrated sulfuric and nitric acids).

Zn+2HCl=ZnCl 2 +H 2

H 2 SO 4 +Zn=ZnSO 4 +H 2

7. Interaction of salt with acid . This reaction will occur provided that the acid forming the salt is weaker or more volatile than the acid that reacted:

Na 2 CO 3 +2HNO 3 =2NaNO 3 +CO 2 +H 2 O

8. Interaction of salt with acid oxide. Reactions occur only when heated, therefore, the reacting oxide must be less volatile than the one formed after the reaction:

CaCO 3 +SiO 2 =CaSiO 3 +CO 2

9. Interaction of non-metal with alkali . Halogens, sulfur and some other elements, interacting with alkalis, give oxygen-free and oxygen-containing salts:

Cl 2 +2KOH=KCl+KClO+H 2 O (reaction occurs without heating)

Cl 2 +6KOH=5KCl+KClO 3 +3H 2 O (the reaction occurs with heating)

3S+6NaOH=2Na 2 S+Na 2 SO 3 +3H 2 O

10. Interaction between two salts. This is the most common method of obtaining salts. To do this, both salts that entered into the reaction must be highly soluble, and since this is an ion exchange reaction, in order for it to proceed to completion, one of the reaction products must be insoluble:

Na 2 CO 3 +CaCl 2 =2NaCl+CaCO 3 ↓

Na 2 SO 4 + BaCl 2 = 2NaCl + BaSO 4 ↓

11. Interaction between salt and metal . The reaction occurs if the metal is in the metal voltage series to the left of the one contained in the salt:

Zn+CuSO 4 =ZnSO 4 +Cu↓

12. Thermal decomposition of salts . When some oxygen-containing salts are heated, new ones are formed, with less oxygen content, or containing no oxygen at all:

2KNO 3 → 2KNO 2 +O 2

4KClO 3 → 3KClO 4 +KCl

2KClO 3 → 3O 2 +2KCl

13. Interaction of a nonmetal with salt. Some non-metals are capable of combining with salts to form new salts:

Cl 2 +2KI=2KCl+I 2 ↓

14. Reaction of base with salt . Since this is an ion exchange reaction, in order for it to proceed to completion, it is necessary that 1 of the reaction products be insoluble (this reaction is also used to convert acidic salts to intermediate ones):

FeCl 3 +3NaOH=Fe(OH) 3 ↓ +3NaCl

NaOH+ZnCl 2 = (ZnOH)Cl+NaCl

KHSO 4 +KOH=K 2 SO 4 +H 2 O

Double salts can also be obtained in this way:

NaOH+ KHSO 4 =KNaSO 4 +H 2 O

15. Interaction of metal with alkali. Metals that are amphoteric react with alkalis, forming complexes:

2Al+2NaOH+6H 2 O=2Na+3H 2

16. Interaction salts (oxides, hydroxides, metals) with ligands:

2Al+2NaOH+6H 2 O=2Na+3H 2

AgCl+3NH 4 OH=OH+NH 4 Cl+2H 2 O

3K 4 +4FeCl 3 =Fe 3 3 +12KCl

AgCl+2NH 4 OH=Cl+2H 2 O

Editor: Galina Nikolaevna Kharlamova

Modern chemical science represents many different branches, and each of them, in addition to its theoretical basis, has great applied and practical significance. Whatever you touch, everything around you is a chemical product. The main sections are inorganic and organic chemistry. Let's consider what main classes of substances are classified as inorganic and what properties they have.

Main categories of inorganic compounds

These include the following:

1. Oxides.
2. Salt.
3. Grounds.
4. Acids.

Each of the classes is represented by a wide variety of compounds of inorganic nature and is important in almost any structure of human economic and industrial activity. All the main properties characteristic of these compounds, their occurrence in nature and their production are studied in a school chemistry course without fail, in grades 8-11.

There is a general table of oxides, salts, bases, acids, which presents examples of each substance and their state of aggregation and occurrence in nature. Interactions that describe chemical properties are also shown. However, we will look at each of the classes separately and in more detail.

Group of compounds - oxides

4. Reactions as a result of which elements change CO

Me +n O + C = Me 0 + CO

1. Reagent water: formation of acids (SiO 2 exception)

CO + water = acid

2. Reactions with bases:

CO 2 + 2CsOH = Cs 2 CO 3 + H 2 O

3. Reactions with basic oxides: salt formation

P 2 O 5 + 3MnO = Mn 3 (PO 3) 2

4. OVR reactions:

CO 2 + 2Ca = C + 2CaO,

They exhibit dual properties and interact according to the principle of the acid-base method (with acids, alkalis, basic oxides, acid oxides). They do not interact with water.

1. With acids: formation of salts and water

AO + acid = salt + H 2 O

2. With bases (alkalis): formation of hydroxo complexes

Al 2 O 3 + LiOH + water = Li

3. Reactions with acid oxides: obtaining salts

FeO + SO 2 = FeSO 3

4. Reactions with OO: formation of salts, fusion

MnO + Rb 2 O = double salt Rb 2 MnO 2

5. Fusion reactions with alkalis and alkali metal carbonates: formation of salts

Al 2 O 3 + 2LiOH = 2LiAlO 2 + H 2 O

Each higher oxide, formed either by a metal or a non-metal, when dissolved in water, gives a strong acid or alkali.

Organic and inorganic acids

In classical sound (based on the positions of ED - electrolytic dissociation - acids are compounds that in an aqueous environment dissociate into cations H + and anions of acid residues An -. However, today acids have been carefully studied in anhydrous conditions, so there are many different theories for hydroxides.

Empirical formulas of oxides, bases, acids, salts consist only of symbols, elements and indices indicating their quantity in the substance. For example, inorganic acids are expressed by the formula H + acid residue n- . Organic substances have a different theoretical representation. In addition to the empirical one, you can write down a full and abbreviated structural formula for them, which will reflect not only the composition and quantity of the molecule, but also the order of the atoms, their connection with each other and the main functional group for carboxylic acids -COOH.

In inorganics, all acids are divided into two groups:

• oxygen-free - HBr, HCN, HCL and others;
• oxygen-containing (oxoacids) - HClO 3 and everything where there is oxygen.

Inorganic acids are also classified by stability (stable or stable - everything except carbonic and sulfurous acids, unstable or unstable - carbonic and sulfurous acids). In terms of strength, acids can be strong: sulfuric, hydrochloric, nitric, perchloric and others, as well as weak: hydrogen sulfide, hypochlorous and others.

Organic chemistry offers not the same variety. Acids that are organic in nature are classified as carboxylic acids. Their common feature is the presence of the -COOH functional group. For example, HCOOH (formic), CH 3 COOH (acetic), C 17 H 35 COOH (stearic) and others.

There are a number of acids that are especially carefully emphasized when considering this topic in a school chemistry course.

1. Solyanaya.
2. Nitrogen.
3. Orthophosphoric.
4. Hydrobromic.
5. Coal.
6. Hydrogen iodide.
7. Sulfuric.
8. Acetic or ethane.
9. Butane or oil.
10. Benzoin.

These 10 acids in chemistry are fundamental substances of the corresponding class both in the school course and in general in industry and syntheses.

Properties of inorganic acids

The main physical properties include, first of all, the different state of aggregation. After all, there are a number of acids that have the form of crystals or powders (boric, orthophosphoric) under normal conditions. The vast majority of known inorganic acids are different liquids. Boiling and melting points also vary.

Acids can cause severe burns, as they have the power to destroy organic tissue and skin. Indicators are used to detect acids:

• methyl orange (in normal environment - orange, in acids - red),
• litmus (in neutral - violet, in acids - red) or some others.

The most important chemical properties include the ability to interact with both simple and complex substances.

When interacting with metals, not all acids react equally. Chemistry (9th grade) at school involves a very shallow study of such reactions, however, even at this level the specific properties of concentrated nitric and sulfuric acid when interacting with metals are considered.

Hydroxides: alkalis, amphoteric and insoluble bases

Oxides, salts, bases, acids - all these classes of substances have a common chemical nature, explained by the structure of the crystal lattice, as well as the mutual influence of atoms in the molecules. However, if it was possible to give a very specific definition for oxides, then this is more difficult to do for acids and bases.

Just like acids, bases, according to the ED theory, are substances that can decompose in an aqueous solution into metal cations Me n+ and anions of hydroxyl groups OH -.

• Soluble or alkalis (strong bases that change Formed by metals of groups I and II. Example: KOH, NaOH, LiOH (that is, elements of only the main subgroups are taken into account);
• Slightly soluble or insoluble (medium strength, do not change the color of indicators). Example: magnesium hydroxide, iron (II), (III) and others.
• Molecular (weak bases, in an aqueous environment they reversibly dissociate into ion molecules). Example: N 2 H 4, amines, ammonia.
• Amphoteric hydroxides (show dual basic-acid properties). Example: beryllium, zinc and so on.

Each group presented is studied in the school chemistry course in the “Fundamentals” section. Chemistry in grades 8-9 involves a detailed study of alkalis and poorly soluble compounds.

Main characteristic properties of bases

All alkalis and slightly soluble compounds are found in nature in a solid crystalline state. At the same time, their melting temperatures are usually low, and poorly soluble hydroxides decompose when heated. The color of the bases is different. If alkalis are white, then crystals of poorly soluble and molecular bases can be of very different colors. The solubility of most compounds of this class can be found in the table, which presents the formulas of oxides, bases, acids, salts, and shows their solubility.

Alkalies can change the color of indicators as follows: phenolphthalein - crimson, methyl orange - yellow. This is ensured by the free presence of hydroxo groups in the solution. That is why poorly soluble bases do not give such a reaction.

The chemical properties of each group of bases are different.

These are most of the chemical properties that bases exhibit. The chemistry of bases is quite simple and follows the general laws of all inorganic compounds.

Class of inorganic salts. Classification, physical properties

Based on the provisions of the ED, salts can be called inorganic compounds that dissociate in an aqueous solution into metal cations Me +n and anions of acidic residues An n-. This is how you can imagine salts. Chemistry gives more than one definition, but this is the most accurate.

Moreover, according to their chemical nature, all salts are divided into:

• Acidic (containing a hydrogen cation). Example: NaHSO 4.
• Basic (containing a hydroxo group). Example: MgOHNO 3, FeOHCL 2.
• Medium (consist only of a metal cation and an acid residue). Example: NaCL, CaSO 4.
• Double (include two different metal cations). Example: NaAl(SO 4) 3.
• Complex (hydroxo complexes, aqua complexes and others). Example: K 2.

The formulas of salts reflect their chemical nature, and also indicate the qualitative and quantitative composition of the molecule.

Oxides, salts, bases, acids have different solubility properties, which can be viewed in the corresponding table.

If we talk about the state of aggregation of salts, then we need to notice their uniformity. They exist only in solid, crystalline or powdery states. The color range is quite varied. Solutions of complex salts, as a rule, have bright, saturated colors.

Chemical interactions for the class of medium salts

They have similar chemical properties as bases, acids, and salts. Oxides, as we have already examined, are somewhat different from them in this factor.

In total, 4 main types of interactions can be distinguished for medium salts.

I. Interaction with acids (only strong from the point of view of ED) with the formation of another salt and a weak acid:

KCNS + HCL = KCL + HCNS

II. Reactions with soluble hydroxides producing salts and insoluble bases:

CuSO 4 + 2LiOH = 2LiSO 4 soluble salt + Cu(OH) 2 insoluble base

III. Reaction with another soluble salt to form an insoluble salt and a soluble one:

PbCL 2 + Na 2 S = PbS + 2NaCL

IV. Reactions with metals located in the EHRNM to the left of the one that forms the salt. In this case, the reacting metal should not interact with water under normal conditions:

Mg + 2AgCL = MgCL 2 + 2Ag

These are the main types of interactions that are characteristic of medium salts. The formulas of complex, basic, double and acidic salts speak for themselves about the specificity of the chemical properties exhibited.

The formulas of oxides, bases, acids, salts reflect the chemical essence of all representatives of these classes of inorganic compounds, and in addition, give an idea of ​​the name of the substance and its physical properties. Therefore, special attention should be paid to their writing. A huge variety of compounds is offered to us by the generally amazing science of chemistry. Oxides, bases, acids, salts - this is only part of the immense diversity.

A large number of reactions leading to the formation of salts are known. We present the most important of them.

1. Interaction of acids with bases (neutralization reaction):

NaOH + HNO 3 = NANO 3 + N 2 ABOUT

Al(OH) 3 + 3HC1 =AlCl 3 + 3H 2 ABOUT

2. Interaction of metals with acids:

Fe + 2HCl = FeCl 2 + N 2 

Zn+ N 2 SABOUT 4 div. = ZnSO 4 + N 2 

3. Interaction of acids with basic and amphoteric oxides:

WITHuO+ N 2 SO 4 = CuSO 4 + N 2 ABOUT

ZnO + 2 HCl = ZnWITHl 2 + N 2 ABOUT

4. Interaction of acids with salts:

FeCl 2 + H 2 S = FeS + 2 HCl

AgNO 3 + HCl = AgCl +HNO 3

Ba(NO 3 ) 2 +H 2 SO 4 =BaSO 4  + 2HNO 3

5. Interaction of solutions of two different salts:

BaCl 2 +Na 2 SO 4 = VaSO 4  +2NаСl

Pb(NO 3 ) 2 + 2NaCl =RbWITH1 2  + 2NaNO 3

6. Interaction of bases with acidic oxides (alkalis with amphoteric oxides):

Ca(OH) 2 + CO 2 = CaCO 3  + N 2 ABOUT,

2 Naon (TV) + ZnO Na 2 ZnO 2 + N 2 ABOUT

7. Interaction of basic oxides with acidic ones:

SaO + SiO 2 SaSiO 3

Na 2 O+SO 3 = Na 2 SO 4

8. Interaction of metals with non-metals:

2K + S1 2 = 2KS1

Fe +S FeS

9. Interaction of metals with salts.

Cu + Hg(NO 3 ) 2 = Hg + Cu(NO 3 ) 2

Pb(NO 3 ) 2 +Zn=Rb + Zn(NO 3 ) 2

10. Interaction of alkali solutions with salt solutions

CuCl 2 + 2NaOH = Cu(OH) 2 ↓+ 2NaCl

NaHCO 3 + NaOH = Na 2 CO 3 +H 2 O

1. Use of salts.

A number of salts are compounds necessary in significant quantities to ensure the vital functions of animal and plant organisms (sodium, potassium, calcium salts, as well as salts containing the elements nitrogen and phosphorus). Below, using examples of individual salts, the areas of application of representatives of this class of inorganic compounds, including in the oil industry, are shown.

NаС1- sodium chloride (table salt, table salt). The breadth of use of this salt is evidenced by the fact that the world production of this substance is more than 200 million tons.

This salt is widely used in the food industry and serves as a raw material for the production of chlorine, hydrochloric acid, sodium hydroxide, and soda ash. (Na 2 CO 3 ). Sodium chloride finds a variety of uses in the oil industry, for example, as an additive to drilling fluids to increase density, prevent the formation of cavities when drilling wells, as a regulator of the setting time of cement grouting compositions, to lower the freezing point (antifreeze) of drilling and cement fluids.

KS1- potassium chloride. Included in drilling fluids that help maintain the stability of well walls in clayey rocks. Potassium chloride is used in significant quantities in agriculture as a macrofertilizer.

Na 2 CO 3 - sodium carbonate (soda). Included in mixtures for glass production and detergents. Reagent for increasing the alkalinity of the environment, improving the quality of clays for clay drilling fluids. It is used to remove the hardness of water when preparing it for use (for example, in boilers), and is widely used for purifying natural gas from hydrogen sulfide and for the production of reagents for drilling and cementing fluids.

Al 2 (SO 4 ) 3 - aluminum sulfate. A component of drilling fluids, a coagulant for purifying water from fine suspended particles, a component of viscoelastic mixtures for isolating absorption zones in oil and gas wells.

NA 2 IN 4 ABOUT 7 - sodium tetraborate (borax). It is an effective reagent - a retarder for cement mortars, an inhibitor of thermal-oxidative destruction of protective reagents based on cellulose ethers.

BASABOUT 4 - barium sulfate (barite, heavy spar). Used as a weighting agent (  4.5 g/cm 3) for drilling and cement slurries.

Fe 2 SO 4 - iron (I) sulfate (iron sulfate). It is used for the preparation of ferrochrome lignosulfonate - a reagent-stabilizer for drilling fluids, a component of highly effective emulsion hydrocarbon-based drilling fluids.

FeS1 3 - ferric chloride (III). In combination with alkali, it is used to purify water from hydrogen sulfide when drilling wells with water, for injection into hydrogen sulfide-containing formations in order to reduce their permeability, as an additive to cements in order to increase their resistance to the action of hydrogen sulfide, to purify water from suspended particles.

CaCO 3 - calcium carbonate in the form of chalk, limestone. It is a raw material for the production of quicklime CaO and slaked lime Ca(OH) 2. Used in metallurgy as a flux. It is used when drilling oil and gas wells as a weighting agent and filler for drilling fluids. Calcium carbonate in the form of marble with a certain particle size is used as a proppant during hydraulic fracturing of productive formations in order to enhance oil recovery.

CaSO 4 - calcium sulfate. In the form of alabaster (2СаSO 4 · Н 2 О) it is widely used in construction, it is part of quick-hardening cementitious mixtures for isolating absorption zones. When added to drilling fluids in the form of anhydrite (CaSO 4) or gypsum (CaSO 4 · 2H 2 O), it imparts stability to the drilled clayey rocks.

CaCl 2 - calcium chloride. Used for preparing drilling and cementing solutions for drilling out unstable rocks, greatly reduces the freezing point of solutions (antifreeze). It is used to create high-density solutions that do not contain a solid phase, effective for opening productive formations.

NA 2 SiABOUT 3 - sodium silicate (soluble glass). Used to consolidate unstable soils and to prepare quick-setting mixtures to isolate absorption zones. It is used as a metal corrosion inhibitor, a component of some drilling cement and buffer solutions.

AgNO 3 - silver nitrate. Used for chemical analysis, including formation waters and drilling fluid filtrates for the content of chlorine ions.

Na 2 SO 3 - sodium sulfite. Used to chemically remove oxygen (deaeration) from water to combat corrosion during wastewater injection. To inhibit the thermal-oxidative destruction of protective reagents.

Na 2 Cr 2 ABOUT 7 - sodium bichromate. It is used in the oil industry as a high-temperature viscosity reducer for drilling fluids, an aluminum corrosion inhibitor, and for the preparation of a number of reagents.