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

Modern chemical science represents a wide variety of industries, and each of them, in addition to the theoretical base, has great applied, practical value. Whatever you touch, everything is a chemical product. The main sections are inorganic and organic chemistry. Consider what the main classes of substances are inorganic and what properties they possess.

The 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 significant in almost any structure of human economic and industrial activity. All the main properties characteristic of these compounds, being in nature and obtaining are studied in the school chemistry course without fail, in grades 8-11.

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

Compound Group - Oxides

Oxides are a class of inorganic compounds consisting of two elements (binary), one of which is always O (oxygen) with a lower oxidation state of -2, which is 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. Non-salt forming - not able to form salts.

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

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

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

Upon dissolution of the higher oxide in water, we obtain the corresponding hydroxide (alkali, acid, or amphoteric hydroxide).

Oxide Characterization

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

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

What do oxides interact with?

Oxides, salts, bases, acids exhibit similar properties. The common properties of almost all oxides (except non-salt-forming ones) are the ability to form various salts as a result of certain interactions. However, each group of oxides is characterized by its special chemical characteristics, reflecting 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 the classical sound (based on the positions of ED - electrolytic dissociation - Svante Arrhenius) acids are compounds that dissociate into H ⁺ cations and anions of An ^- acid residues in an aqueous medium. However, acids have been thoroughly studied today under anhydrous conditions, so there are many different theories for hydroxides.

The empirical formulas of oxides, bases, acids, salts are composed only of symbols, elements and indices indicating their amount in a substance. For example, inorganic acids are expressed by the formula H ⁺ acid residue ^n- . Organic matter has a different theoretical mapping. In addition to the empirical one, a complete and abridged structural formula can be written for them, which will reflect not only the composition and quantity of the molecule, but also the order of arrangement of the atoms, their relationship with each other, and the main functional group for carboxylic acids — COOH.

In an inorganic, all acids are divided into two groups:

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

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

Organic chemistry offers no such variety. Acids that are organic in nature are carboxylic acids. Their common feature is the presence of a functional group - UNC. 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. Salt.
2. Nitric
3. Phosphoric.
4. Hydrobromic.
5. Coal.
6. Hydrogen iodide.
7. Sulfur.
8. Acetic or ethane.
9. Butane, or oily.
10. Benzoic.

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

Inorganic Acid Properties

The main physical properties should be attributed primarily to a different state of aggregation. After all, there are a number of acids that have the form of crystals or powders (boric, phosphoric) under ordinary 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. To detect acids use indicators:

• methyl orange (in a normal environment - orange, in acids - red),
• litmus (in neutral it is violet, in acids it is 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 (grade 9) in the school involves a very shallow study of such reactions, however, and 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, due to the structure of the crystal lattice, as well as the mutual influence of atoms in the composition of the molecules. However, if for oxides it was possible to give a very specific definition, then for acids and bases it is more difficult to do.

Like acids, bases according to the theory of ED are called substances that can decompose in an aqueous solution into metal cations Me ^{n +} and anions of OH ^- hydroxo groups.

It can be divided into categories of foundation as follows:

• Soluble or alkalis (strong bases that change the color of indicators). 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, not changing the color of the indicators). Example: magnesium hydroxide, iron (II), (III) and others.
• Molecular (weak bases, reversibly dissociate into molecular ions in an aqueous medium). Example: N ₂ H _4, amines, ammonia.
• Amphoteric hydroxides (exhibit dual basic acid properties). Example: aluminum hydroxide, beryllium, zinc and so on.

Each presented group is studied in a school chemistry course in the "Foundations" section. Chemistry of grades 8–9 implies a detailed study of alkalis and sparingly soluble compounds.

The main characteristic properties of the bases

All alkalis and sparingly soluble compounds are in nature in a solid crystalline state. At the same time, their melting points are, as a rule, low, and sparingly soluble hydroxides decompose upon heating. The color of the bases is different. If alkalis are white, then crystals of sparingly soluble and molecular bases can be of very different colors. The solubility of most compounds of this class can be seen in the table, which presents the formulas of oxides, bases, acids, salts, their solubility is shown.

Alkalis are able to change the color of indicators as follows: phenolphthalein - raspberry, methyl orange - yellow. This is ensured by the free presence of hydroxo groups in 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 the majority of the chemical properties that exhibit bases. Base chemistry is quite simple and obeys the general laws of all inorganic compounds.

Class of inorganic salts. Classification, physical properties

Based on the position of ED, salts can be called inorganic compounds that dissociate in an aqueous solution into metal cations Me ^{+ n} and anions of acid residues An ^n- . So you can imagine the salt. Chemistry gives more than one definition, but it is the most accurate.

Moreover, by their chemical nature, all salts are divided into:

• Acidic (containing a hydrogen cation). Example: NaHSO _4.
• Basic (containing a hydroxy 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 (hydroxocomplexes, aquacomplexes and others). Example: K ₂ [Fe (CN) ₄ ].

The 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, which can be seen in the corresponding table.

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

Chemical interactions for the class of medium salts

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

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

I. Interaction with acids (only strong in terms of ED) with the formation of another salt and a 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 an ECM to the left of what forms a salt. In this case, the metal entering the reaction should not under normal conditions interact with water:

Mg + 2AgCL = MgCL ₂ + 2Ag

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

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, their writing should pay special attention. A huge variety of compounds offers us a generally amazing science - chemistry. Oxides, bases, acids, salts - this is only part of an immense variety.