Oxides, salts, bases, acids. Properties of oxides, bases, acids, salts

Modern chemical science is a variety of diverse industries, and each of them, in addition to the theoretical basis, has great practical importance, practical. Whatever you touch, everything around is the products of chemical production. The main sections are inorganic and organic chemistry. Let us consider what main classes of substances are attributed to inorganic and what properties they possess.

Main categories of inorganic compounds

To those it is customary to include the following:

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

Each of the classes is represented by a great variety of compounds of inorganic nature and has significance in virtually any structure of the economic and industrial activity of man. All the main properties characteristic of these compounds, finding in nature and receiving are studied in the school course of chemistry, without fail, in grades 8-11.

There is a general table of oxides, salts, bases, acids, in which are presented examples of each of the substances and their aggregate state, being in nature. Also, interactions describing chemical properties are shown. However, we will cover each of the classes separately and in more detail.

Group of compounds - oxides

Oxides are a class of inorganic compounds consisting of two elements (binary), one of which is always O (oxygen) with a low degree of oxidation -2, standing in second place in the empirical formula of the substance. Example: N ₂ O _5, CaO and so on.

Oxides are classified as follows.

I. Nesoobrazuyuschie - not able to form salts.

II. Salt-forming - are able to form salts (with bases, amphoteric compounds, with each other, acids).

1. Acidic acids - when they get into the water they form acids. Formed by non-metals more often than metals with high CO (degree of oxidation).
2. The main ones - when entering the water form bases. Formed by metal elements.
3. Amphoteric - show acid-base double nature, which is determined by the reaction conditions. They are formed by transition metals.
4. Mixed - often refer to salts and formed by elements in several degrees of oxidation.

The higher oxide is an oxide in which the forming element is in the maximum oxidation state. Example: Te ⁺⁶ _. For tellurium, the maximum degree of oxidation is +6, then TeO ₃ is the highest oxide for this element. In the periodic system, under each group of elements, a general empirical formula is signed that reflects the highest oxide for all elements in this group, but only the main subgroup. For example, under the first group of elements (alkali metals) there is a formula of the form R ₂ O, which means that all elements of the main subgroup in this group will have exactly this formula of higher oxide. Example: Rb ₂ O, Cs ₂ O and so on.

When the higher oxide is dissolved in water, we get the corresponding hydroxide (alkali, acid or amphoteric hydroxide).

Characterization of oxides

Oxides can exist in all aggregate states under normal conditions. Most of them are in solid crystalline or powder form (CaO, SiO ₂ ), some KO (acid oxides) occur as liquids (Mn ₂ O ₇ ), as well as gases (NO, NO ₂ ). This is explained by the structure of the crystal lattice. Hence the difference in the boiling and melting points, which vary in different representatives from -272 ⁰ C to + 70-80 ⁰ C (sometimes even higher). The solubility in water is different.

1. Soluble - basic metal oxides, called alkaline, alkaline earth, and all acidic, except silicon oxide (IV).
2. Insoluble - amphoteric oxides, all other basic and SiO _2.

What do oxides interact with?

Oxides, salts, bases, acids show similar properties. The general properties of virtually all oxides (except non-salt-forming) is the ability to form various salts as a result of certain interactions. However, for each group of oxides are characterized by their specific chemical characteristics, reflecting properties.

Properties of different oxide groups

Basic oxides - GS	Acidic oxides - CO	Dual (amphoteric) oxides - AO	Oxides that do not form salts
1. Reactions with water: the formation of alkalis (oxides of alkali and alkaline earth metals) Fr 2 O + water = 2FrOH 2. Reactions with acids: formation of salts and water acid + Me + n O = H 2 O + salt 3. Reactions with CO, formation of salts and water Lithium oxide + nitrogen oxide (V) = 2LiNO 3 4. Reactions, as a result of which elements change CO Me + n O + C = Me 0 + CO	1. Reagent water: acid formation (SiO 2 elimination) KO + 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 + 3 MnO = Mn 3 (PO 3 ) 2 4. OVR reactions: CO 2 + 2Ca = C + 2CaO,	They exhibit double properties, interact according to the principle of the acid-base method (with acids, alkalis, basic oxides, acid oxides). Water does not interact with water. 1. With acids: the formation of salts and water AO + acid = salt + H 2 O 2. With bases (alkalis): formation of hydroxycomplexes Al 2 O 3 + LiOH + water = Li [Al (OH) 4 ] 3. Reactions with acidic oxides: the preparation of salts FeO + SO 2 = FeSO 3 4. Reactions with OO: formation of salts, fusion MnO + Rb 2 O = double salt of Rb 2 MnO 2 5. Fusion reactions with alkali and alkali metal carbonates: salt formation Al 2 O 3 + 2 LiOH = 2LiAlO 2 + H 2 O	Do not form acids or alkalis. They show very specific properties.

Each higher oxide, formed by both metal and non-metal, dissolving in water, gives a strong acid or alkali.

Organic and inorganic acids

In classical sounding (based on the positions of ED - electrolytic dissociation - Svante Arrhenius), acids are compounds dissociating into cations of H ⁺ in an aqueous medium and anions of acid residues An ^- . However, today the acids are thoroughly studied in anhydrous conditions, so there are many different theories for hydroxides.

Empirical formulas of oxides, bases, acids, salts are composed only of symbols, elements and indices, indicating their quantity in matter. For example, inorganic acids are expressed by the formula H ⁺ acid residue ^n- . Organic matter has another theoretical representation. In addition to empirical, they can write a complete and abbreviated structural formula, which will reflect not only the composition and quantity of the molecule, but also the order of the atoms, their relationship to each other and the main functional group for carboxylic acids -COOH.

Inorganic all acids are divided into two groups:

• Anoxic - HBr, HCN, HCL and others;
• Oxygen-containing (oxo acids) - HClO ₃ and all where there is oxygen.

Also, inorganic acids are classified by stability (stable or stable - everything except coal and sulphide, unstable or unstable - coal and sulfur). The strength of acids can be strong: sulfuric, hydrochloric, nitric, chloric and others, and also weak: hydrogen sulphide, hypochlorous and others.

Organic chemistry does not offer such a variety. Acids, which are of an organic nature, refer to carboxylic acids. Their common feature is the presence of the functional group -COOH. For example, HCOOH (formic), CH ₃ COOH (acetic), C ₁₇ H ₃₅ COOH (stearic) and others.

There are a number of acids, which are particularly carefully emphasized when considering this topic in the school course of chemistry.

1. Salt.
2. Nitrogen.
3. Orthophosphoric.
4. Hydrobromic acid.
5. Coal.
6. Hydrogen iodide.
7. Sulfur.
8. Acetic, or ethane.
9. Butane, or oil.
10. Benzoic.

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

Properties of inorganic acids

To the basic physical properties it is necessary to attribute first of all a different aggregate state. After all, there are a number of acids that look like crystals or powders (boric, orthophosphoric) under normal conditions. The vast majority of known inorganic acids are different liquids. The boiling and melting points also vary.

Acids can cause severe burns, since they have a force that destroys organic tissues and skin. To detect acids use indicators:

• Methylorange (in usual medium - orange, in acids - red),
• Litmus (in neutral - purple, in acids - red) or some others.

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

Chemical properties of inorganic acids

With what they interact	Example reaction
1. With simple metals. A prerequisite: the metal must stand in the EHRNM to hydrogen, since the metals that stand after hydrogen can not displace it from the acid composition. As a result of the reaction, hydrogen is always formed in the form of gas and salt.	HCL + AL = aluminum chloride + H 2
2. With bases. The reaction result is salt and water. Such reactions of strong acids with alkalis are called neutralization reactions.	Any acid (strong) + soluble base = salt and water
3. With amphoteric hydroxides. Result: salt and water.	2HNO 2 + beryllium hydroxide = Be (NO 2 ) 2 (average salt) + 2H 2 O
4. With basic oxides. Result: water, salt.	2HCL + FeO = ferric chloride (II) + H 2 O
5. With amphoteric oxides. The final effect: salt and water.	2HI + ZnO = ZnI 2 + H 2 O
6. With salts formed by weaker acids. The final effect: salt and weak acid.	2HBr + MgCO 3 = magnesium bromide + H 2 O + CO 2

Not all acids respond equally to the interaction with metals. Chemistry (grade 9) in school presupposes a very shallow study of such reactions, but at this level specific properties of concentrated nitric and sulfuric acid are also considered when interacting with metals.

Hydroxides: alkalis, amphoteric and insoluble bases

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

As well as acids, the bases on the theory of ED are substances capable of decomposing into metal cations Me ^{n +} and anions of hydroxyl groups OH ^- in aqueous solution.

Divide into categories of the basis can be as follows:

• Soluble or alkali (strong bases that change the color of the indicators). Formed by metals of groups I, II. Example: KOH, NaOH, LiOH (that is, only the main subgroups are taken into account);
• Low soluble or insoluble (medium strength, not changing the color of the indicators). Example: magnesium hydroxide, iron (II), (III) and others.
• Molecular (weak bases, in an aqueous medium, reversibly dissociate into ion-molecules). Example: N ₂ H _4, amines, ammonia.
• Amphoteric hydroxides (exhibit dual basic-acid properties). Example: aluminum hydroxide, beryllium, zinc hydroxide and so on.

Each group represented is studied in the school chemistry course in the "Foundations" section. Chemistry 8-9 class implies a detailed study of alkalis and poorly soluble compounds.

The main characteristic properties of bases

All alkalis and poorly soluble compounds are in nature in a solid crystalline state. At the same time, their melting points are generally low, and poorly soluble hydroxides decompose on heating. The color of the bases is different. If the alkali is white, then the crystals of sparingly soluble and molecular bases can be of a very different color. The solubility of most compounds of this class can be found in the table in which oxides, bases, acids, salts are presented, their solubility is shown.

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

The chemical properties of each group of bases are different.

Chemical properties
Alkalis	Low-soluble bases	Amphoteric hydroxides
I. Interact with KO (total-salt and water): 2LiOH + SO 3 = Li 2 SO 4 + water II. Interact with acids (salt and water): Conventional neutralization reactions (see acids) III. Interact with the AO to form a hydroxo complex of salt and water: 2NaOH + Me + n O = Na 2 Me + n O 2 + H 2 O, or Na 2 [Me + n (OH) 4 ] IV. Interact with amphoteric hydroxides with the formation of hydroxo-complex salts: The same as with AO, only without water V. Interact with soluble salts with the formation of insoluble hydroxides and salts: 3CsOH + ferric chloride (III) = Fe (OH) 3 + 3CsCl VI. Interact with zinc and aluminum in an aqueous solution to form salts and hydrogen: 2RbOH + 2Al + water = complex with hydroxide ion 2Rb [Al (OH) 4 ] + 3H 2	I. When heated, they can decompose: Insoluble hydroxide = oxide + water II. Reactions with acids (total: salt and water): Fe (OH) 2 + 2HBr = FeBr 2 + water III. Interact with KO: Me + n (OH) n + KO = salt + H 2 O	I. React with acids to form salt and water: Copper (II) hydroxide + 2HBr = CuBr 2 + water II. React with alkalis: total - salt and water (condition: fusion) Zn (OH) 2 + 2CsOH = salt + 2H 2 O III. React with strong hydroxides: the result is salts if the reaction is in aqueous solution: Cr (OH) 3 + 3RbOH = Rb 3 [Cr (OH) 6 ]

This is most of the chemical properties that show the basis. The chemistry of bases is quite simple and obeys the general laws of all inorganic compounds.

Class of inorganic salts. Classification, physical properties

Based on the provisions of ED, salts can be called inorganic compounds, in an aqueous solution dissociating into metal cations Me ^{+ n} and anions of acid residues An ^n- . So you can imagine the salt. The definition of chemistry does not give one, but this is the most accurate.

At the same time in its chemical nature, all salts are divided into:

• Acidic (containing a hydrogen cation). Example: NaHSO _4.
  
• The main (having in the composition of the hydroxy group). Example: MgOHNO ₃ , FeOHCL _2.
• Medium (consist only of metal cation and acid residue). Example: NaCl, CaSO _4.
• Double (include two different metal cations). Example: NaAl (SO4) _3.
• Complex (hydrocomplexes, aquacomplexes and others). Example: K ₂ [Fe (CN) ₄ ].

Salt formulas reflect their chemical nature, and also talk about the qualitative and quantitative composition of the molecule.

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

If we talk about the aggregate state of salts, we must note their monotony. They exist only in a solid, crystalline or powdery state. The color scheme is quite diverse. Solutions of complex salts, as a rule, have bright saturated colors.

Chemical interactions for a class of medium salts

They have similar chemical properties of base, acid, salt. Oxides, as we have already seen, differ somewhat from them in this factor.

In total, there are 4 main types of interactions for medium salts.

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

KCNS + HCL = KCL + HCNS

II. Reactions with soluble hydroxides with the appearance of salts and insoluble bases:

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

III. Interaction with another soluble salt to form an insoluble salt and soluble:

PbCL ₂ + Na ₂ S = PbS + 2NaCL

IV. Reactions with metals standing in the ECHRN to the left of what forms the salt. In this case, the metal reacting under the normal conditions should not interact with water:

Mg + 2AgCL = MgCL ₂ + 2Ag

These are the main types of interactions that are characteristic of medium salts. The formulas of salts of complex, basic, double and acidic ones speak for themselves of 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 also give an idea of the name of the substance and its physical properties. Therefore, their writing should pay special attention. A huge variety of compounds offers us in general an amazing science - chemistry. Oxides, bases, acids, salts - this is only part of the immense variety.