acids- electrolytes, during the dissociation of which only H + ions are formed from positive ions:
HNO 3 ↔ H + + NO 3 -;
CH 3 COOH ↔ H + +CH 3 COO -.
All acids are classified into inorganic and organic (carboxylic), which also have their own (internal) classifications.
Under normal conditions, a significant amount inorganic acids exist in a liquid state, some in a solid state (H 3 PO 4, H 3 BO 3).
Organic acids with up to 3 carbon atoms are easily mobile, colorless liquids with a characteristic pungent odor; acids with 4-9 carbon atoms are oily liquids with an unpleasant odor, and acids with a large number of carbon atoms are solids that are insoluble in water.
Chemical formulas of acids
Consider the chemical formulas of acids using the example of several representatives (both inorganic and organic): hydrochloric acid -HCl, sulfuric acid - H 2 SO 4, phosphoric acid - H 3 PO 4, acetic acid - CH 3 COOH and benzoic acid - C 6 H5COOH. The chemical formula shows the qualitative and quantitative composition of the molecule (how many and which atoms are included in a particular compound) Using the chemical formula, you can calculate the molecular weight of acids (Ar (H) \u003d 1 amu, Ar (Cl) \u003d 35.5 a.m.). m.u., Ar(P) = 31 a.m.u., Ar(O) = 16 a.m.u., Ar(S) = 32 a.m.u., Ar(C) = 12 a.u.m.):
Mr(HCl) = Ar(H) + Ar(Cl);
Mr(HCl) = 1 + 35.5 = 36.5.
Mr(H 2 SO 4) = 2×Ar(H) + Ar(S) + 4×Ar(O);
Mr(H 2 SO 4) \u003d 2 × 1 + 32 + 4 × 16 \u003d 2 + 32 + 64 \u003d 98.
Mr(H 3 PO 4) = 3×Ar(H) + Ar(P) + 4×Ar(O);
Mr(H 3 PO 4) \u003d 3 × 1 + 31 + 4 × 16 \u003d 3 + 31 + 64 \u003d 98.
Mr(CH 3 COOH) = 3×Ar(C) + 4×Ar(H) + 2×Ar(O);
Mr(CH 3 COOH) = 3x12 + 4x1 + 2x16 = 36 + 4 + 32 = 72.
Mr(C 6 H 5 COOH) = 7×Ar(C) + 6×Ar(H) + 2×Ar(O);
Mr(C 6 H 5 COOH) = 7x12 + 6x1 + 2x16 = 84 + 6 + 32 = 122.
Structural (graphic) formulas of acids
The structural (graphic) formula of a substance is more visual. It shows how atoms are connected to each other within a molecule. Let us indicate the structural formulas of each of the above compounds:
Rice. 1. Structural formula of hydrochloric acid.
Rice. 2. Structural formula of sulfuric acid.
Rice. 3. Structural formula of phosphoric acid.
Rice. 4. Structural formula of acetic acid.
Rice. 5. Structural formula of benzoic acid.
Ionic formulas
All inorganic acids are electrolytes, i.e. capable of dissociating in an aqueous solution into ions:
HCl ↔ H + + Cl - ;
H 2 SO 4 ↔ 2H + + SO 4 2-;
H 3 PO 4 ↔ 3H + + PO 4 3-.
Examples of problem solving
EXAMPLE 1
| The task | With the complete combustion of 6 g of organic matter, 8.8 g of carbon monoxide (IV) and 3.6 g of water were formed. Determine the molecular formula of the burned substance if its molar mass is known to be 180 g/mol. |
| Solution | Let's make a scheme of the combustion reaction organic compound denoting the number of carbon, hydrogen and oxygen atoms as "x", "y" and "z", respectively: C x H y O z + O z →CO 2 + H 2 O. Let us determine the masses of the elements that make up this substance. The values of relative atomic masses taken from the Periodic Table of D.I. Mendeleev, rounded up to integers: Ar(C) = 12 a.m.u., Ar(H) = 1 a.m.u., Ar(O) = 16 a.m.u. m(C) = n(C)×M(C) = n(CO 2)×M(C) = ×M(C); m(H) = n(H)×M(H) = 2×n(H 2 O)×M(H) = ×M(H); Calculate the molar masses of carbon dioxide and water. As is known, the molar mass of a molecule is equal to the sum of the relative atomic masses of the atoms that make up the molecule (M = Mr): M(CO 2) \u003d Ar (C) + 2 × Ar (O) \u003d 12+ 2 × 16 \u003d 12 + 32 \u003d 44 g / mol; M(H 2 O) \u003d 2 × Ar (H) + Ar (O) \u003d 2 × 1 + 16 \u003d 2 + 16 \u003d 18 g / mol. m(C)=×12=2.4 g; m (H) \u003d 2 × 3.6 / 18 × 1 \u003d 0.4 g. m(O) \u003d m (C x H y O z) - m (C) - m (H) \u003d 6 - 2.4 - 0.4 \u003d 3.2 g. Let's define the chemical formula of the compound: x:y:z = m(C)/Ar(C) : m(H)/Ar(H) : m(O)/Ar(O); x:y:z= 2.4/12:0.4/1:3.2/16; x:y:z= 0.2: 0.4: 0.2 = 1: 2: 1. Means the simplest formula compounds CH 2 O and a molar mass of 30 g / mol. To find the true formula of an organic compound, we find the ratio of the true and obtained molar masses: M substance / M (CH 2 O) \u003d 180 / 30 \u003d 6. This means that the indices of carbon, hydrogen and oxygen atoms should be 6 times higher, i.e. the formula of the substance will look like C 6 H 12 O 6. Is it glucose or fructose. |
| Answer | C6H12O6 |
EXAMPLE 2
| The task | Derive the simplest formula of a compound in which the mass fraction of phosphorus is 43.66%, and the mass fraction of oxygen is 56.34%. |
| Solution | The mass fraction of element X in a molecule of composition HX is calculated from following formula:
ω (X) = n × Ar (X) / M (HX) × 100%. Let us denote the number of phosphorus atoms in the molecule as "x", and the number of oxygen atoms as "y" Let us find the corresponding relative atomic masses of the elements phosphorus and oxygen (the values of the relative atomic masses taken from the Periodic Table of D.I. Mendeleev will be rounded up to whole numbers). Ar(P) = 31; Ar(O) = 16. We divide the percentage of elements by the corresponding relative atomic masses. Thus, we will find the relationship between the number of atoms in the molecule of the compound: x:y = ω(P)/Ar(P) : ω(O)/Ar(O); x:y = 43.66/31: 56.34/16; x:y: = 1.4: 3.5 = 1: 2.5 = 2: 5. This means that the simplest formula for the combination of phosphorus and oxygen has the form P 2 O 5. It is phosphorus(V) oxide. |
| Answer | P2O5 |
Classification of inorganic substances with examples of compounds
Let us now analyze the classification scheme presented above in more detail.
As we can see, first of all, all inorganic substances are divided into simple And complex:
simple substances substances that are formed by atoms of only one chemical element are called. For example, simple substances are hydrogen H 2 , oxygen O 2 , iron Fe, carbon C, etc.
Among simple substances, there are metals, nonmetals And noble gases:
Metals are formed by chemical elements located below the boron-astat diagonal, as well as by all elements that are in side groups.
noble gases formed by chemical elements of group VIIIA.
non-metals formed, respectively, by chemical elements located above the boron-astat diagonal, with the exception of all elements of secondary subgroups and noble gases located in group VIIIA:
The names of simple substances most often coincide with the names of the chemical elements whose atoms they are formed. However, for many chemical elements, the phenomenon of allotropy is widespread. Allotropy is the phenomenon when one chemical element is able to form several simple substances. For example, in the case of the chemical element oxygen, the existence of molecular compounds with the formulas O 2 and O 3 is possible. The first substance is usually called oxygen in the same way as the chemical element whose atoms it is formed, and the second substance (O 3) is usually called ozone. The simple substance carbon can mean any of its allotropic modifications, for example, diamond, graphite or fullerenes. The simple substance phosphorus can be understood as its allotropic modifications, such as white phosphorus, red phosphorus, black phosphorus.
Complex Substances
complex substances Substances made up of atoms of two or more elements are called.
So, for example, complex substances are ammonia NH 3, sulfuric acid H 2 SO 4, slaked lime Ca (OH) 2 and countless others.
Among complex inorganic substances, 5 main classes are distinguished, namely oxides, bases, amphoteric hydroxides, acids and salts:
oxides - complex substances formed by two chemical elements, one of which is oxygen in the -2 oxidation state.
The general formula for oxides can be written as E x O y, where E is the symbol of a chemical element.
Nomenclature of oxides
The name of the oxide of a chemical element is based on the principle:
For example:
Fe 2 O 3 - iron oxide (III); CuO, copper(II) oxide; N 2 O 5 - nitric oxide (V)
Often you can find information that the valency of the element is indicated in brackets, but this is not the case. So, for example, the oxidation state of nitrogen N 2 O 5 is +5, and the valency, oddly enough, is four.
If a chemical element has a single positive oxidation state in compounds, then the oxidation state is not indicated. For example:
Na 2 O - sodium oxide; H 2 O - hydrogen oxide; ZnO is zinc oxide.
Classification of oxides
Oxides, according to their ability to form salts when interacting with acids or bases, are divided, respectively, into salt-forming And non-salt-forming.
There are few non-salt-forming oxides, all of them are formed by non-metals in the oxidation state +1 and +2. The list of non-salt-forming oxides should be remembered: CO, SiO, N 2 O, NO.
Salt-forming oxides, in turn, are divided into main, acidic And amphoteric.
Basic oxides called such oxides, which, when interacting with acids (or acid oxides), form salts. The main oxides include metal oxides in the oxidation state +1 and +2, with the exception of oxides of BeO, ZnO, SnO, PbO.
Acid oxides called such oxides, which, when interacting with bases (or basic oxides), form salts. Acid oxides are practically all oxides of non-metals, with the exception of non-salt-forming CO, NO, N 2 O, SiO, as well as all metal oxides in high oxidation states (+5, +6 and +7).
amphoteric oxides called oxides, which can react with both acids and bases, and as a result of these reactions form salts. Such oxides exhibit a dual acid-base nature, that is, they can exhibit the properties of both acidic and basic oxides. Amphoteric oxides include metal oxides in oxidation states +3, +4, and, as exceptions, oxides of BeO, ZnO, SnO, PbO.
Some metals can form all three types of salt-forming oxides. For example, chromium forms basic oxide CrO, amphoteric oxide Cr 2 O 3 and acid oxide CrO 3 .
As can be seen, the acid-base properties of metal oxides directly depend on the degree of oxidation of the metal in the oxide: the higher the degree of oxidation, the more pronounced the acid properties.
Foundations
Foundations - compounds with a formula of the form Me (OH) x, where x most often equal to 1 or 2.
Base classification
Bases are classified according to the number of hydroxo groups in one structural unit.
Bases with one hydroxo group, i.e. type MeOH, called single acid bases with two hydroxo groups, i.e. type Me(OH) 2 , respectively, diacid etc.
Also, the bases are divided into soluble (alkali) and insoluble.
Alkalis include exclusively hydroxides of alkali and alkaline earth metals, as well as thallium hydroxide TlOH.
Base nomenclature
The name of the foundation is built according to the following principle:
For example:
Fe (OH) 2 - iron (II) hydroxide,
Cu (OH) 2 - copper (II) hydroxide.
In cases where the metal in complex substances has a constant oxidation state, it is not required to indicate it. For example:
NaOH - sodium hydroxide,
Ca (OH) 2 - calcium hydroxide, etc.
acids
acids - complex substances, the molecules of which contain hydrogen atoms that can be replaced by a metal.
The general formula of acids can be written as H x A, where H are hydrogen atoms that can be replaced by a metal, and A is an acid residue.
For example, acids include compounds such as H 2 SO 4 , HCl, HNO 3 , HNO 2 , etc.
Acid classification
According to the number of hydrogen atoms that can be replaced by a metal, acids are divided into:
- about monobasic acids: HF, HCl, HBr, HI, HNO 3 ;
- d acetic acids: H 2 SO 4 , H 2 SO 3 , H 2 CO 3 ;
- T rebasic acids: H 3 PO 4 , H 3 BO 3 .
It should be noted that the number of hydrogen atoms in the case of organic acids most often does not reflect their basicity. For example, acetic acid with the formula CH 3 COOH, despite the presence of 4 hydrogen atoms in the molecule, is not four-, but monobasic. The basicity of organic acids is determined by the number of carboxyl groups (-COOH) in the molecule.
Also, according to the presence of oxygen in acid molecules, they are divided into anoxic (HF, HCl, HBr, etc.) and oxygen-containing (H 2 SO 4, HNO 3, H 3 PO 4, etc.). Oxygenated acids are also called oxo acids.
You can read more about the classification of acids.
Nomenclature of acids and acid residues
The following list of names and formulas of acids and acid residues should be learned.
In some cases, a number of the following rules can make memorization easier.
As can be seen from the table above, the construction of the systematic names of anoxic acids is as follows:
For example:
HF, hydrofluoric acid;
HCl, hydrochloric acid;
H 2 S - hydrosulfide acid.
The names of the acid residues of oxygen-free acids are built according to the principle:
For example, Cl - - chloride, Br - - bromide.
The names of oxygen-containing acids are obtained by adding various suffixes and endings to the name of the acid-forming element. For example, if the acid-forming element in an oxygen-containing acid has the highest oxidation state, then the name of such an acid is constructed as follows:
For example, sulfuric acid H 2 S +6 O 4, chromic acid H 2 Cr +6 O 4.
All oxygen-containing acids can also be classified as acidic hydroxides, since hydroxo groups (OH) are found in their molecules. For example, this can be seen from the following graphical formulas of some oxygen-containing acids:
Thus, sulfuric acid can otherwise be called sulfur (VI) hydroxide, nitric acid - nitrogen (V) hydroxide, phosphoric acid - phosphorus (V) hydroxide, etc. The number in brackets characterizes the degree of oxidation of the acid-forming element. Such a variant of the names of oxygen-containing acids may seem extremely unusual to many, however, occasionally such names can be found in real KIMs of the Unified State Examination in chemistry in assignments for the classification of inorganic substances.
Amphoteric hydroxides
Amphoteric hydroxides - metal hydroxides exhibiting a dual nature, i.e. able to exhibit both the properties of acids and the properties of bases.
Amphoteric are metal hydroxides in oxidation states +3 and +4 (as well as oxides).
Also, compounds Be (OH) 2, Zn (OH) 2, Sn (OH) 2 and Pb (OH) 2 are included as exceptions to amphoteric hydroxides, despite the degree of oxidation of the metal in them +2.
For amphoteric hydroxides of tri- and tetravalent metals, the existence of ortho- and meta-forms is possible, differing from each other by one water molecule. For example, aluminum (III) hydroxide can exist in the ortho form of Al(OH) 3 or the meta form of AlO(OH) (metahydroxide).
Since, as already mentioned, amphoteric hydroxides exhibit both the properties of acids and the properties of bases, their formula and name can also be written differently: either as a base or as an acid. For example:
salt
So, for example, salts include compounds such as KCl, Ca(NO 3) 2, NaHCO 3, etc.
The above definition describes the composition of most salts, however, there are salts that do not fall under it. For example, instead of metal cations, the salt may contain ammonium cations or its organic derivatives. Those. salts include compounds such as, for example, (NH 4) 2 SO 4 (ammonium sulfate), + Cl - (methylammonium chloride), etc.
Salt classification
On the other hand, salts can be considered as products of substitution of hydrogen cations H + in an acid for other cations, or as products of substitution of hydroxide ions in bases (or amphoteric hydroxides) for other anions.
With complete substitution, the so-called medium or normal salt. For example, with the complete replacement of hydrogen cations in sulfuric acid with sodium cations, an average (normal) salt Na 2 SO 4 is formed, and with the complete replacement of hydroxide ions in the Ca (OH) 2 base with acid residues, nitrate ions form an average (normal) salt Ca(NO3)2.
Salts obtained by incomplete replacement of hydrogen cations in a dibasic (or more) acid with metal cations are called acid salts. So, with incomplete replacement of hydrogen cations in sulfuric acid by sodium cations, an acid salt NaHSO 4 is formed.
Salts that are formed by incomplete substitution of hydroxide ions in two-acid (or more) bases are called basic about salts. For example, with incomplete replacement of hydroxide ions in the Ca (OH) 2 base with nitrate ions, a basic about clear salt Ca(OH)NO 3 .
Salts consisting of cations of two different metals and anions of acid residues of only one acid are called double salts. So, for example, double salts are KNaCO 3 , KMgCl 3 , etc.
If the salt is formed by one type of cation and two types of acid residues, such salts are called mixed. For example, mixed salts are the compounds Ca(OCl)Cl, CuBrCl, etc.
There are salts that do not fall under the definition of salts as products of substitution of hydrogen cations in acids for metal cations or products of substitution of hydroxide ions in bases for anions of acid residues. These are complex salts. So, for example, complex salts are sodium tetrahydroxozincate and tetrahydroxoaluminate with the formulas Na 2 and Na, respectively. Recognize complex salts, among others, most often by the presence of square brackets in the formula. However, it must be understood that in order for a substance to be classified as a salt, its composition must include any cations, except for (or instead of) H +, and from the anions there must be any anions in addition to (or instead of) OH -. For example, the compound H 2 does not belong to the class of complex salts, since only hydrogen cations H + are present in solution during its dissociation from cations. According to the type of dissociation, this substance should rather be classified as an oxygen-free complex acid. Similarly, the OH compound does not belong to the salts, because this compound consists of cations + and hydroxide ions OH -, i.e. it should be considered a complex basis.
Salt nomenclature
Nomenclature of medium and acid salts
The name of medium and acid salts is based on the principle:
If the degree of oxidation of the metal in complex substances is constant, then it is not indicated.
The names of the acid residues were given above when considering the nomenclature of acids.
For example,
Na 2 SO 4 - sodium sulfate;
NaHSO 4 - sodium hydrosulfate;
CaCO 3 - calcium carbonate;
Ca (HCO 3) 2 - calcium bicarbonate, etc.
Nomenclature of basic salts
The names of the main salts are built according to the principle:
For example:
(CuOH) 2 CO 3 - copper (II) hydroxocarbonate;
Fe (OH) 2 NO 3 - iron (III) dihydroxonitrate.
Nomenclature of complex salts
The nomenclature of complex compounds is much more complicated, and for passing the exam You don't need to know much about the nomenclature of complex salts.
One should be able to name complex salts obtained by the interaction of alkali solutions with amphoteric hydroxides. For example:
*The same colors in the formula and the name indicate the corresponding elements of the formula and the name.
Trivial names of inorganic substances
Trivial names are understood as the names of substances that are not related, or weakly related to their composition and structure. Trivial names are due, as a rule, either historical reasons or the physical or chemical properties of these compounds.
List of trivial names of inorganic substances that you need to know:
| Na 3 | cryolite |
| SiO2 | quartz, silica |
| FeS 2 | pyrite, iron pyrite |
| CaSO 4 ∙2H 2 O | gypsum |
| CaC2 | calcium carbide |
| Al 4 C 3 | aluminum carbide |
| KOH | caustic potash |
| NaOH | caustic soda, caustic soda |
| H2O2 | hydrogen peroxide |
| CuSO 4 ∙5H 2 O | blue vitriol |
| NH4Cl | ammonia |
| CaCO3 | chalk, marble, limestone |
| N2O | laughing gas |
| NO 2 | brown gas |
| NaHCO3 | food (drinking) soda |
| Fe 3 O 4 | iron oxide |
| NH 3 ∙H 2 O (NH 4 OH) | ammonia |
| CO | carbon monoxide |
| CO2 | carbon dioxide |
| SiC | carborundum (silicon carbide) |
| PH 3 | phosphine |
| NH3 | ammonia |
| KClO 3 | berthollet salt (potassium chlorate) |
| (CuOH) 2 CO 3 | malachite |
| CaO | quicklime |
| Ca(OH)2 | slaked lime |
| transparent aqueous solution of Ca(OH) 2 | lime water |
| a suspension of solid Ca (OH) 2 in its aqueous solution | milk of lime |
| K2CO3 | potash |
| Na2CO3 | soda ash |
| Na 2 CO 3 ∙10H 2 O | crystal soda |
| MgO | magnesia |
| Acid formulas | Names of acids | Names of the corresponding salts |
| HClO 4 | chloride | perchlorates |
| HClO 3 | chlorine | chlorates |
| HClO 2 | chloride | chlorites |
| HClO | hypochlorous | hypochlorites |
| H5IO6 | iodine | periodates |
| HIO 3 | iodine | iodates |
| H2SO4 | sulfuric | sulfates |
| H2SO3 | sulphurous | sulfites |
| H2S2O3 | thiosulfuric | thiosulfates |
| H2S4O6 | tetrathionic | tetrathionates |
| HNO3 | nitric | nitrates |
| HNO 2 | nitrogenous | nitrites |
| H3PO4 | orthophosphoric | orthophosphates |
| HPO 3 | metaphosphoric | metaphosphates |
| H3PO3 | phosphorous | phosphites |
| H3PO2 | phosphorous | hypophosphites |
| H2CO3 | coal | carbonates |
| H2SiO3 | silicon | silicates |
| HMnO 4 | manganese | permanganates |
| H2MnO4 | manganese | manganates |
| H2CrO4 | chrome | chromates |
| H2Cr2O7 | dichrome | dichromates |
| HF | hydrofluoric (hydrofluoric) | fluorides |
| HCl | hydrochloric (hydrochloric) | chlorides |
| HBr | hydrobromic | bromides |
| HI | hydroiodic | iodides |
| H 2 S | hydrogen sulfide | sulfides |
| HCN | hydrocyanic | cyanides |
| HOCN | cyanic | cyanates |
Let me briefly remind concrete examples how to properly name salts.
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 salt contains iron and a residue of hydrochloric acid(Cl). Name of the salt: iron(III) chloride. Please note: in this case we must not only 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 valence!
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 valency 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 of obtaining them and Chemical properties, I recommend referring to the relevant sections of the reference book on chemistry: "
Complex substances consisting of hydrogen atoms and an acidic residue are called mineral or inorganic acids. The acid residue is oxides and non-metals combined with hydrogen. The main property of acids is the ability to form salts.
Classification
The basic formula of mineral acids is H n Ac, where Ac is the acid residue. Depending on the composition of the acid residue, two types of acids are distinguished:
- oxygen containing oxygen;
- oxygen-free, consisting only of hydrogen and non-metal.
The main list of inorganic acids according to the type is presented in the table.
|
Type |
Name |
Formula |
|
Oxygen |
||
|
nitrogenous |
||
|
dichrome |
||
|
Iodine |
||
|
Silicon - metasilicon and orthosilicon |
H 2 SiO 3 and H 4 SiO 4 |
|
|
manganese |
||
|
manganese |
||
|
Metaphosphoric |
||
|
Arsenic |
||
|
orthophosphoric |
||
|
sulphurous |
||
|
Thiosulphuric |
||
|
Tetrathionic |
||
|
Coal |
||
|
Phosphorous |
||
|
Phosphorous |
||
|
Chlorine |
||
|
Chloride |
||
|
hypochlorous |
||
|
Chrome |
||
|
cyanic |
||
|
Anoxic |
Hydrofluoric (hydrofluoric) |
|
|
Hydrochloric (hydrochloric) |
||
|
Hydrobromic |
||
|
Hydroiodine |
||
|
Hydrogen sulfide |
||
|
Hydrogen cyanide |
In addition, in accordance with the properties of the acid are classified according to the following criteria:
- solubility: soluble (HNO 3 , HCl) and insoluble (H 2 SiO 3);
- volatility: volatile (H 2 S, HCl) and non-volatile (H 2 SO 4 , H 3 PO 4);
- degree of dissociation: strong (HNO 3) and weak (H 2 CO 3).
Rice. 1. Scheme for the classification of acids.
Traditional and trivial names are used to designate mineral acids. The traditional names correspond to the name of the element that forms the acid with the addition of the morphemic -naya, -ovaya, as well as -pure, -novataya, -novatistaya to indicate the degree of oxidation.
Receipt
The main methods for obtaining acids are presented in the table.
Properties
Most acids are sour-tasting liquids. Tungsten, chromic, boric and several other acids are in a solid state under normal conditions. Some acids (H 2 CO 3, H 2 SO 3, HClO) exist only in the form of an aqueous solution and are weak acids.
Rice. 2. Chromic acid.
Acids are active substances that react:
- with metals:
Ca + 2HCl \u003d CaCl 2 + H 2;
- with oxides:
CaO + 2HCl \u003d CaCl 2 + H 2 O;
- with base:
H 2 SO 4 + 2KOH \u003d K 2 SO 4 + 2H 2 O;
- with salts:
Na 2 CO 3 + 2HCl \u003d 2NaCl + CO 2 + H 2 O.
All reactions are accompanied by the formation of salts.
A qualitative reaction is possible with a change in the color of the indicator:
- litmus turns red;
- methyl orange - in pink;
- phenolphthalein does not change.
Rice. 3. Colors of indicators during acid interaction.
The chemical properties of mineral acids are determined by the ability to dissociate in water with the formation of hydrogen cations and anions of hydrogen residues. Acids that react with water irreversibly (dissociate completely) are called strong acids. These include chlorine, nitrogen, sulfuric and hydrochloric.
What have we learned?
Inorganic acids are formed by hydrogen and an acidic residue, which are non-metal atoms or an oxide. Depending on the nature of the acid residue, acids are classified into anoxic and oxygen-containing. All acids have a sour taste and are able to dissociate in an aqueous medium (decompose into cations and anions). Acids are obtained from simple substances, oxides, salts. When interacting with metals, oxides, bases, salts, acids form salts.
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