3 classification of inorganic compounds nomenclature definitions. Classification of inorganic compounds and their properties
simple substances and chemical compounds. Oxides: basic, acidic and amphoteric. Nomenclature of oxides. The dependence of the acid-base character of oxides on the position in periodic system and the oxidation state of the element. Chemical interaction between oxides to form salts. Basic and amphoteric hydroxides, acids. Their nomenclature and receipt. Salts: normal, acidic and basic. Salt nomenclature. Preparation and properties of salts.
Nomenclature and properties of complex compounds.
Inorganic compounds are distinguished by composition (binary and multielement) and functional features. TO binary compounds include compounds of elements with oxygen ( oxides), halogens ( halides– fluorides, chlorides, bromides, iodides), chalcogens ( chalcogenides- sulfides, selenides, tellurides), nitrogen (nitrides), phosphorus (phosphides), carbon (carbides), silicon ( silicides), as well as compounds of metals with each other ( intermetallics) and hydrogen ( hydrides). Among multi-element compounds are isolated hydroxides(substances containing hydroxide groups - OH), derivatives of hydroxides - salt, and complex compounds, hydrates And crystalline hydrates.
In accordance with IUPAC rules, the name of any substance must clearly indicate its composition. Therefore, the basis of systematic.e. The name of any substance should unambiguously indicate its composition, therefore, the basis of the system and compounds, these ratios of names inorganic substances the names of the elements included in their composition are given.
The name of a binary compound is formed from the Latin root of the name of the more electronegative element with the ending -id and the Russian name of the less electronegative element in genitive case. When writing the formula of a substance, the less electronegative element is to the left. For example, Al 2 O 3 is aluminum oxide, AgI is silver iodide, OF 2 is oxygen fluoride. For some elements, the roots of their Russian names coincide with the roots of Latin ones, with the exception of the elements presented in Table 1 below:
Table 1
Titles chemical elements
Symbol notation | Russian name | Latin name |
Ag | Silver | Argent- |
As | Arsenic | Ars-, arsen- |
Au | Gold | Aur- |
C | Carbon | Carb-, carbon- |
Cu | Copper | Cupr- |
Fe | Iron | Ferr- |
H | Hydrogen | Hydro-, hydrogen- |
N | Nitrogen | Nitr- |
Ni | Nickel | Nikkol- |
O | Oxygen | Ox-, oxygen- |
Pb | Lead | Plumb- |
S | Sulfur | Sulf-, thio- |
Sb | Antimony | Stib- |
Si | Silicon | Sil-, Silic-, Silic- |
hg | Mercury | Merkur- |
Mn | Manganese | Mangan- |
sn | Tin | Stann- |
To indicate the quantitative composition, Greek numerals are used as a prefix, for example, Hg 2 Cl 2 - dirtutium dichloride, CO - carbon monoxide, CO 2 - carbon dioxide.
Numerical prefixes have the following names:
1 - Mono- 5 - penta- 9 -Nona-
2 - Di- 6 - Hexa- 10 -Deca-
3 - Three- 7- Hepta- 11 -Undeca-
4 - Tetra- 8 - Octa- 12- Dodeca-.
The name of a multielement compound reflects its functional characteristics, such as belonging to hydroxides or acids. Hydroxides are compounds of oxides with water. They are subdivided into basic, exhibiting the properties of bases in chemical reactions, acidic- showing the properties of acids, amphoteric– capable of exhibiting both acidic and basic properties.
To the class grounds, according to the theory electrolytic dissociation, include substances capable of dissociating in an aqueous solution to form hydroxide ions OH - : The name of the basic hydroxide (or base) is formed from the word "hydroxide" and the name of the element in the genitive case, followed, if necessary, by the oxidation state of the element. For example, NaOH is sodium hydroxide, Fe (OH) 2 is iron (II) hydroxide or iron dihydroxide. The general formula for a base can be written as M(OH) m, where M is a metal, m is the number of hydroxyl groups, or base acidity.
Substances capable of dissociating in solution to form hydrogen ions H + , in accordance with the theory of electrolytic dissociation, they belong to the class acids.
Acids, depending on the presence of oxygen in their composition, are divided into oxygen-containing and on anoxic. In general, the formula of an acid can be written as H n A, where A is the acid residue, n is the number of hydrogen atoms in the molecule, or acid basicity.
The systematic name of an acid includes the name of two parts: electropositive (hydrogen atoms) and electronegative (acid residue, anion). In the name of the anion, first indicate the oxygen atoms (-oxo-), then the acid-forming element with the addition of the suffix -at, then in brackets the absolute value of the oxidation state of this element. For example, H 2 CO 3 is hydrogen trioxocarbonate (IY), H 2 SO 4 is hydrogen tetraoxosulfate (VI). If there are other atoms in the anion, the name of the anion is made up of the Latin roots of the names of the corresponding elements and the connecting vowel -o- in the order they are placed in the formula from right to left. For example, H 2 SO 3 (O 2) is hydrogen peroxotrioxosulfate (VI), H 2 SO 3 S is hydrogen thiotrioxosulfate (VI). The systematic names of the most commonly used acids are presented in table 3.
The traditional name consists of two words - an adjective derived from the root of the name of the acid-forming element, and the word "acid", for example, H 2 SO 4 - sulfuric acid, HNO 3 - Nitric acid.
Amphoteric hydroxides able to dissociate in aqueous solutions both as bases and as acids, for example,
When interacting with acids, they exhibit the properties of bases, and when interacting with bases, they exhibit the properties of acids. Their names are compiled according to the scheme corresponding to the basic hydroxides.
table 2
Names of the most important acids and their salts
Acid Formula | Titles | |
acids | salt | |
HAlO 2 | Metaaluminum | Metaaluminate |
HAso 3 | Metaarsenic | Metaarsenate |
H 3 AsO 4 | orthoarsenic | orthoarsenate |
HAso 2 | Metaarsenous | Metaarsenite |
H 3 AsO 3 | Ortharsenous | orthoarsenite |
HBO 2 | metabornaya | Metaborate |
H3BO3 | orthoborn | orthoborate |
H2B4O7 | Quadruple | tetraborate |
HBr | Hydrogen bromide | Bromide |
HOBr | Bromous | Hypobromite |
HBrO 3 | bromine | Bromate |
HCOOH | Formic | Formate |
CH3COOH | Acetic | Acetate |
HCN | Hydrogen cyanide | Cyanide |
H2CO3 | Coal | Carbonate |
H 2 C 2 O 4 | sorrel | Oxalate |
HCl | Hydrogen chloride | Chloride |
HOCl | hypochlorous | Hypochlorite |
HClO 2 | Chloride | Chlorite |
HClO 3 | Chlorine | Chlorate |
HClO 4 | Chloric | Perchlorate |
HCrO 2 | metachromic | Metachromite |
H2CrO4 | Chrome | Chromate |
H2Cr2O7 | double chrome | dichromate |
HI | Hydrogen iodine | Iodide |
HOI | iodine | Hypoioditis |
HIO 3 | Iodine | Yodat |
HIO 4 | Iodine | Periodat |
HMnO 4 | manganese | Permanganate |
H2MnO4 | manganese | manganate |
H2MoO4 | molybdenum | Molybdate |
HN 3 | Hydrogen azidide (hydrazoic) | Azide |
HNO 2 | nitrogenous | Nitrite |
HNO3 | Nitrogen | Nitrate |
HPO 3 | Metaphosphoric | Metaphosphate |
H3PO4 | orthophosphoric | orthophosphate |
H4P2O7 | Diphosphoric (pyrophosphoric) | Diphosphate (pyrophosphate) |
H3PO3 | Phosphorous | Phosphite |
H3PO2 | phosphorous | Hypophosphite |
H 2 S | hydrogen sulfide | Sulfide |
HSCN | Rhodohydrogen | rhodanide |
H2SO3 | sulphurous | Sulfite |
H2SO4 | sulfuric | Sulfate |
H2S2O3 | Thiosulphuric | thiosulfate |
H2S2O7 | Two-sulfur (pyrosulfur) | Disulfate (pyrosulfate) |
H2S2O8 | Peroxo-two-sulphuric (nadsulphuric) | Peroxidosulfate (persulfate) |
H 2 Se | hydrogen selenium | selenide |
H 2 SeO 3 | selenist | Selenite |
H 2 SeO 4 | Selenic | Selenate |
H2SiO3 | Silicon | Silicate |
HVO 3 | Vanadium | Vanadat |
H2WO4 | Tungsten | Tungstate |
salt are products of substitution of hydrogen ions of an acid for a metal or hydroxyl groups of a base for an acid residue. Depending on the completeness of substitution of hydrogen atoms or hydroxyl groups, salts are divided into medium(or normal), for example K 2 SO 4, sour(or hydrosalts) for example NaHCO 3 , and main(or hydroxosalts) such as FeOHCl. There are also double salts, formed by two metals and one acid residue (KAl (SO 4) 2), and mixed salts formed by one metal and two acid residues (CaClOCl). The names of the salts are determined by the systematic names of the corresponding acids, for example, K 2 SO 4 is potassium tetraoxosulfate (VI), NaHCO 3 is hydrogen-sodium trioxocarbonate (IY), FeOHCl or, more precisely, FeClOH is iron (II) hydroxy chloride.
In the presence of numerical prefixes (1, 2, . . .) in the name of the substance, for a correct understanding of the formula, the multiplication of the prefix is \u200b\u200bused (for example, КАl 3 (SO 4) 2 (OH) 6 - trialuminum-potassium hexahydroxide-bis (sulfate)). The attachment names are as follows:
1 Monokis- 5 Pentakis- 9 Nonakis-
3 Tris- 7Heptakis- 11Undekasis-
The traditional names of salts also contain the names of anions in the nominative case and the names of cations in the genitive case (see Table 2), for example, K 2 SO 4 is potassium sulfate, NaHCO 3 is sodium bicarbonate, FeOHCl is iron (II) hydroxochloride.
oxides depending on the characteristic functions performed in chemical reactions, they are divided into salt-forming(among them are basic, acidic and amphoteric) and non-salt-forming.
Basic oxides form salts when reacting with acids or acid oxides. They correspond to bases, since they form them when interacting with water, for example, CaO - Ca (OH) 2.
Acid oxides form salts when interacting with bases or basic oxides. They can be obtained by separating water from the corresponding acid. Therefore they are also called anhydrides acids, for example SO 3 - anhydride H 2 SO 4.
Amphoteric oxides form salts both when interacting with acids and when interacting with bases, for example, ZnO, Al 2 O 3.
Hydrates And crystalline hydrates- compounds containing water in their composition, for example, NH 3 ∙ H 2 O ∙ Fe 2 O 3, n H 2 O, CuSO 4 ∙ 5H 2 O. Both systematic and traditional names of such compounds begin with the word “hydrate” with the appropriate prefix: NH 3 ∙ H 2 O - ammonia hydrate, Fe 2 O 3 ∙ n H 2 O - iron oxide polyhydrate (III), CuSO 4 ∙ 5H 2 O - copper (II) tetraoxosulfate pentahydride, or copper (II) sulfate pentahydride.
Lecture 5. Chemical thermodynamics
Chemical thermodynamics. Thermodynamic systems. Thermodynamic parameters. thermodynamic process. Internal energy, heat, work. First law of thermodynamics. Enthalpy. Hess's law and consequences from it. Entropy. The second law of thermodynamics. Gibbs free energy and free energy Helgmoltz.
Chemical thermodynamics.
Thermodynamics studies the mutual transformation of heat, work and various kinds energy. The word thermodynamics comes from the Greek words thermos (heat) and dynamos (strength, power). The term thermodynamics was introduced by Thomson in 1854, who used it as a synonym for heat and work.
Thermodynamics is based on three fundamental principles, which are called the principles of thermodynamics. They are a generalization of numerous experimental facts.
Application of thermodynamic methods to chemical reactions and processes led to the emergence of chemical thermodynamics. The subject of study of chemical thermodynamics is the conversion of energy during chemical interactions that occur during chemical processes.
Thermodynamic systems. Thermodynamic parameters. thermodynamic process.
Thermodynamics uses a number of concepts and model representations, such as a thermodynamic system, state parameters, energy, heat, and work. Let's move on to their consideration.
The concept of a system means that part of the material world that we are exploring. For example, a chemical beaker with water, a reactor at a chemical plant. The rest of the material world, outside the conventionally allocated system, is called the environment.
thermodynamic system- is called a set of bodies, which actually or mentally can be isolated from the environment. The system is separated from the environment by a boundary through which material exchange takes place - mass transfer and/or heat transfer. Depending on the degree of isolation, open, closed, isolated systems are distinguished.
open systems- These are systems that exchange matter, mechanical work, heat and radiation with the external environment. For example, sodium carbonate (soda) is mixed in a test tube with a solution of hydrochloric acid. The result is a reaction
Na 2 CO 3 + HCl \u003d NaCl + CO 2 + H 2 O.
In the chemical process under consideration, the mass of the system decreases, since carbon dioxide escapes and heat is released, part of which is used to heat the surrounding air.
Closed systems- systems that do not exchange matter with the external environment, but interact with it through mechanical work, heat transfer and radiation. An example of a closed system is a test tube in which soda is mixed with hydrochloric acid, closed with a stopper.
Isolated systems- systems that do not interact with the external environment. There is no exchange of matter or energy between an isolated system and its environment. In practice, the concept of absolutely isolated systems does not exist, it is an abstract, mental construction. An example of an approximately isolated system is a thermos or Dewar vessel.
The system can be in one state or another. state system is called a set of physical and chemical properties that characterize the system.
The state of a thermodynamic system is characterized by state parameters: pressure, volume, temperature, concentration.
Pressure (P) characterizes the mobility of molecules and is determined by the force with which gaseous particles act on the walls of the vessel. Pressure is measured in Pa (Pascal), atm (atmosphere), mm Hg. Art. (millimeters of mercury): 1 atm = 760 mmHg. Art. = 101325 Pa.
Volume (V) characterizes the part of the space occupied by the substance. The volume is measured in m 3 (cubic meter), cm 3 (cubic centimeter), l (liter), ml (milliliter): 1 m 3 \u003d 1000 l; 1l = 1000 ml.
Temperature (T, t) characterizes the degree of heating of the system and is measured in K (Kelvin scale) and 0 C (Celsius scale). To convert temperatures expressed in different scales, use the expression
T = t + 273 (1).
Concentration substance (s) determines quantitative composition solution, mixture, melt. For example, molar concentration - the number of moles of a substance in 1 liter of a solution or mixture, is denoted by mol / l.
Thus, the set of parameters (p, V, T) is called the state of the system, since it is considered that it completely determines the state. Thermodynamic parameters are macroscopic quantities measured in the experiment. They are state functions, that is, their change is determined only by the initial and final states and does not depend on the path of the process that resulted in this change.
∆ T \u003d T con - T initial \u003d T 2 - T 1 (2).
For infinitesimal changes, we can write
∆ Т = dT (3).
If a value is not a state function, but depends on the path of the process, then it is a transition function. In this case, an infinitesimal change in A is written as
∆А = δА (4).
Thus, the sign ∆ - denotes a change in the value, which is a function of the state, the sign δ - denotes a change in the value, which is a transition function.
The thermodynamic parameters are not independent, but are related by the equation of state. An example of such an equation is the equation of state for an ideal gas, which is called the Mendeleev-Claiperon equation
where n is the number of moles of gas; R is the gas constant.
The state of a thermodynamic system can change over time. Typically, such a change is recorded when one of the thermodynamic parameters is measured. Therefore, in thermodynamics, the concept of a thermodynamic process is used.
thermodynamic process Any change in the system associated with a change in at least one parameter is called. Thus, a thermodynamic process is a change in the state of a system. The following processes are distinguished: isochoric (V = const), isobaric (p = const), isothermal (T = const), adiabatic (heat Q = 0).
Thermodynamic processes are:
-reversible, when the transition from one state to another and back can occur along the same path, and after returning to the initial state in environment no macroscopic changes remain; an example of a reversible process is the compression and extension of a spring;
-irreversible or nonequilibrium, when the parameters change at a finite rate and the transition from one state to another and back cannot occur along the same path, as a result, macroscopic changes remain in the environment; an example of an irreversible process is the plastic deformation of a metal wire.
Internal energy, heat, work.
In addition to thermodynamic parameters, other thermodynamic quantities, such as work and heat, also play an important role. They are a quantitative measure of thermodynamic processes and characterize the participation of the system in thermodynamic processes. Work and heat are energy characteristics. Therefore, consider the concept of energy.
Energy comes from the Greek word "action" - there is a measure of the ability to do work. Energy is measured in J (Joule). Numerous observations and experimental facts speak of the following properties of energy.
Energy does not disappear and does not arise from nothing.
Energy can exist in a variety of forms.
In an isolated system, energy can change from one form to another, but its amount remains constant.
If the system is not isolated, then its energy can change, but with a simultaneous change in energy external environment by exactly the same amount.
Any system has a certain amount of energy, that is, energy is an integral property of the system.
For the consideration of chemical processes, the following forms of energy are important: solar, mechanical, chemical, nuclear, electrical.
The following types of energy are distinguished: kinetic (energy of motion), potential (energy of position and interaction) and internal energy (energy of state).
In chemistry, the whole variety of inorganic substances: it is customary to divide into two groups - simple and complex. Elements are divided into metals and non-metals. And complex ones - into derivatives of simple ones, formed by their interaction with oxygen, water and with each other. This classification of inorganic substances in the form of a diagram is depicted as follows:
Rice. 2.1. Classification of inorganic compounds.
Classification of reactions in inorganic chemistry. In inorganic chemistry, reactions are distinguished: 1) compounds, 2) decomposition (both of which may or may not be redox reactions), 3) exchange, 4) substitution, which are always redox reactions. Reaction schemes and examples are given in Table 2.1.
Table 2.1
Reaction classification
Consider the preparation and properties of the most important classes of inorganic compounds.
OXIDES(oxides) - complex substances consisting of two elements, one of which is oxygen in an oxidation state of -2. The general formula for any oxide is E x O y -2. Distinguish salt-forming (main: Li 2 O, CaO, MgO, FeO; amphoteric: ZnO, Al 2 O 3 , SnO 2 , Cr 2 O 3 , Fe 2 O 3 ; acidic: B 2 O 3 , SO 3 , CO 2 , P 2 O 5 Mn 2 O 7) and non-salt-forming: N 2 O, NO, CO oxides. Elements with a variable oxidation state form several oxides (MnO, MnO 2, Mn 2 O 7, NO, N 2 O 3, NO 2, N 2 O 5). In the higher oxide, as a rule, the element is in the oxidation state equal to the group number.
According to modern international nomenclature, the names of oxides are as follows: the word "oxide", hereinafter Russian name element in the genitive case, the oxidation state of the element (if it is variable). For example: FeO - iron oxide (II), P 2 O 5 - phosphorus oxide (V).
Basic oxides these are those that correspond to hydroxides - bases. The main ones are oxides that interact with acids to form salt and water. Basic oxides are formed only by metals in the oxidation state +1, +2 (sometimes +3), for example: BaO, SrO, FeO, MnO, CrO, Li 2 O, Bi 2 O 3, Ag 2 O.
Obtaining basic oxides:
1) Oxidation of metals when heated in an oxygen atmosphere:
This method is practically inapplicable for alkali metals, which usually give peroxides during oxidation, so Na 2 O, K 2 O oxides are extremely difficult to obtain.
2) Sulfide roasting:
2СuS+3O 2 =2CuO+2SO 2 ;
4FeS 2 + 11O 2 \u003d 2Fe 2 O 3 + 8SO 2.
3) Decomposition of hydroxides:
Cu(OH) 2 \u003d CuO + H 2 O.
Alkali metal oxides cannot be obtained by this method.
4) Decomposition of salts of some oxygen-containing acids:
BaCO 3 \u003d BaO + CO 2,
2Pb(NO 3) 2 \u003d 2PbO + 4NO 2 + O 2
Properties of basic oxides. Most basic oxides are ionic crystalline solids; at the nodes of the crystal lattice there are metal ions that are quite strongly associated with O 2- ions; therefore, oxides of typical metals have high melting and boiling points.
We note one characteristic feature of oxides. The proximity of the ionic radii of many metal ions leads to the fact that in the crystal lattice of oxides, part of the ions of one metal can be replaced by ions of another metal. This leads to the fact that the law of constant composition is often not satisfied for oxides, and mixed oxides of variable composition can exist.
1) Attitude to water.
The process of adding water is called hydration, and the resulting substance is called hydroxide. Of the basic oxides, only oxides of alkali (Li, Na, K, Rb, Cs, Fr) and alkaline earth metals (Ca, Sr, Ba, Ra) interact with water.
Li 2 O+H 2 O=2LiOH;
BaO + H 2 O \u003d Ba (OH) 2.
Most basic oxides do not dissolve in water and do not interact with it. Their corresponding hydroxides are obtained indirectly - by the action of alkalis on salts (see below).
2) Relation to acids.
CaO + H 2 SO 4 \u003d CaSO 4 + H 2 O;
FeO + 2HCl \u003d FeCl 2 + H 2 O.
3) Relation to acidic and amphoteric oxides.
Basic oxides of alkali and alkaline earth metals, when fused, interact with solid acidic and amphoteric oxides, as well as with gaseous acidic oxides under normal conditions.
CaO + CO 2 \u003d CaCO 3;
3BaO+P 2 O 5 \u003d Ba 3 (PO 4) 2;
fusion
Li 2 O + Al 2 O 3 \u003d 2LiAlO 2.
fusion
Basic oxides of less active metals interact only with solid acidic oxides during fusion.
Acidic oxides- oxides, which, when interacting with bases, form salt and water. Acid oxides correspond to hydroxides - acids. Acid oxides are non-metal oxides in various oxidation states, or metal oxides in a high oxidation state (+4 and higher). Examples: SO 2, SO 3, Cl 2 O 7, Mn 2 O 7, CrO 3.
The chemical bond in acid oxides is covalent polar. Under normal conditions, acidic oxides of non-metals can be gaseous (CO 2, SO 2), liquid (N 2 O 3, Cl 2 O 7), solid (P 2 O 5, SiO 2).
Obtaining acid oxides.
1) Oxidation of non-metals:
2) Sulfide oxidation:
2ZnS + 3O 2 \u003d 2ZnO + 2SO 2
3) Displacement of fragile weak acids from their salts:
CaCO 3 + 2HCl \u003d CaCl 2 + CO 2 + H 2 O.
Properties of acid oxides.
1) Attitude to water.
Most acidic oxides dissolve in water, entering into chemical interaction with it and forming acids:
SO 3 + H 2 O \u003d H 2 SO 4,
CO 2 +H 2 O \u003d H 2 CO 3.
2) Attitude to the grounds.
Acid oxides interact with soluble bases - alkalis, forming salt and water.
SO 2 + 2NaOH \u003d Na 2 SO 3 + H 2 O;
P 2 O 5 + 6NaOH \u003d 2Na 3 PO 4 + 3H 2 O
fusion
3) Relation to basic and amphoteric oxides.
Solid acidic oxides interact with basic and amphoteric oxides during fusion. Liquid and gaseous oxides interact with oxides of alkali and alkaline earth metals under normal conditions.
P 2 O 5 + 3CuO \u003d Cu 3 (PO 4) 2;
fusion
3SiO 2 + Al 2 O 3 \u003d Al 2 (SiO 3) 3
fusion
Amphoteric oxides interact with both acids and alkalis, showing the properties of acidic and basic oxides. They correspond to amphoteric hydroxides. They are all solids, insoluble in water. Examples of amphoteric oxides: ZnO, BeO, SnO, PbO, Al 2 O 3 , Cr 2 O 3 , Sb 2 O 3 , MnO 2 .
Properties of amphoteric oxides.
Amphoteric oxides react with acids as basic ones:
Al 2 O 3 + 6HCl \u003d 2AlCl 3 + 3H 2 O,
and with alkalis - as acidic. The composition of the reaction products depends on the conditions. When fused:
ZnO + 2NaOH \u003d Na 2 ZnO 2 + H 2 O;
sodium zincate
In an alkali solution, a soluble complex salt containing a hydroxo complex ion is formed:
ZnO + 2NaOH + H 2 O \u003d Na 2
Sodium tetrahydroxozincate
Non-salt-forming oxides - these are oxides of non-metals, which do not correspond to hydroxides and salts. Examples: CO, N 2 O, NO, SiO.
Oxides are widely distributed in nature. So water - the most common oxide covers 71% of the planet's surface. Silicon (IV) oxide in the form of 400 varieties of quartz is 12% by weight earth's crust. Carbon monoxide(IV) ( carbon dioxide) is found in the atmosphere - 0.03% by volume, as well as in natural waters. The most important ores: hematite, magnetite, brown iron ore are composed of various iron oxides. Bauxite contains aluminum oxide, etc.
GROUNDS- complex substances in which there is one or more hydroxo groups OH - per metal atom. The oxidation state of metal atoms is usually +1, +2 (rarely +3). The general formula of the bases is Me (OH) x, where x is the number of hydroxo groups - the acidity of the base. (MeOH - one-acid, Me (OH) 2 - two-acid, Me (OH) 3 - three-acid base).
The names of the bases are given as follows: "hydroxide", then the Russian name of the metal in the genitive case, and in brackets in Roman numerals - the oxidation state, if it is variable. For example: KOH is potassium hydroxide, Ni (OH) 2 is nickel (II) hydroxide.
Under normal conditions, bases are solids, except for ammonium hydroxide, an aqueous solution of ammonia NH 4 OH (NH 4 + is the ammonium ion that is part of ammonium salts).
Base classification. Depending on their relationship to water, bases are divided into soluble (alkali) And insoluble. Soluble bases - alkalis include only hydroxides of alkali and alkaline earth metals (LiOH, NaOH, KOH, CsOH, RbOH, FrOH, Ca (OH) 2, Sr (OH) 2, Ba (OH) 2, Ra (OH) 2) and also an aqueous solution of ammonia. All other bases are practically insoluble in water.
From the point of view of the theory of electrolytic dissociation, bases are electrolytes that dissociate in an aqueous solution with the formation of only hydroxide ions as anions:
Me (OH) x Me x + + xOH -.
The presence of hydroxide ions in a solution is determined using indicators: litmus (blue), phenolphthalein (raspberry), methyl orange (yellow). Insoluble bases do not change the color of indicators.
Substance classification
All substances are divided into simple (elementary) and complex. Simple substances are made up of one element, while complex substances are made up of two or more elements. Simple substances are divided into metals and non-metals.
Metals have a characteristic "metallic" luster, are malleable, malleable, can be rolled into sheets or drawn into wire, have good thermal and electrical conductivity. At room temperature, all metals (except mercury) are in a solid state.
Non-metals do not have the characteristic luster of metals, are brittle, and conduct heat and electricity very poorly. Some of them are gaseous under normal conditions.
Complex substances are divided into organic and inorganic (mineral). It is customary to call carbon compounds organic, with the exception of the simplest carbon compounds (CO, CO 2, H 2 CO 3, HCN and their salts, etc.); all other substances are called inorganic.
Complex inorganic compounds are classified both by composition and by chemical properties (functional characteristics). By composition, they are primarily divided into two-element, or binary, compounds (oxides, sulfides, halides, nitrides, carbides, hydrides) and multi-element compounds; oxygen-containing, nitrogen-containing, etc.
According to their chemical properties, inorganic compounds are divided into four main classes: oxides, acids, bases, salts.
oxides
Oxides are complex substances consisting of two elements, one of which is oxygen(Cr 2 O 3 , K 2 O, CO 2 etc.). Oxygen in oxides is always bivalent and has an oxidation state of -2.
According to their chemical properties, oxides are divided into salt-forming and non-salt-forming oxides.(indifferent: CO, NO, N 2 O). Salt-forming oxides are divided into basic, acidic and amphoteric.
The main ones are oxides that interact with acids or acid oxides, with the formation of salts:
CuO + 2HCl \u003d CuCl 2 + H 2 O,
MgO + CO 2 \u003d MgCO 3.
The formation of basic oxides is typical for metals with a low degree of oxidation (+1, +2).
Oxides of alkali (Li, Na, K, Rb, Cs) and alkaline earth metals (Ca, Sr, Ba, Ra) interact with water, forming bases. For example:
Na 2 O + H 2 O \u003d 2NaOH,
CaO + H 2 O \u003d Ca (OH) 2.
Most of basic oxides do not interact with water. The bases of such oxides are obtained indirectly:
a) CuO + 2HCl=CuCl 2 + H 2 O;
b) CuCl 2 + 2KOH = Cu(OH) 2 + 2KCl.
Acidic oxides are oxides that react with bases or basic oxides to form salts. For example:
SO 3 + 2KOH \u003d K 2 SO 4 + H 2 O,
CaO + CO 2 \u003d CaCO 3.
Acid oxides include oxides of typical non-metals-SO 2 , N 2 O 5 , SiO 2 , CO 2 etc., as well as metal oxides with a high degree of oxidation (+5, +6, +7, +8)-V 2 O 5, CrO 3, Mn 2 O 7, etc.
A number of acid oxides (SO 3, SO 2, N 2 O 3, N 2 O 5, CO 2, etc.) form acids when interacting with water:
SO 3 + H 2 O \u003d H 2 SO 4,
N 2 O 5 + H 2 O \u003d 2HNO 3.
The corresponding acids of other acidic oxides (SiO 2 , TeO 2 , TeO 3 , MoO 3 , WO 3 , etc.) are obtained indirectly. For example:
a) SiO 2 + 2NaOH \u003d Na 2 SiO 3 + H 2 O
b) Na 2 SiO 3 + 2HCl \u003d H 2 SiO 3 + 2NaCl
One way to obtain acid oxides is to remove water from the corresponding acids. Therefore, acid oxides are sometimes called acid anhydrides.
Amphoteric oxides are oxides that form salts when interacting with both acids and bases, that is, they have dual properties - the properties of basic and acidic oxides. For example:
SnO + H 2 SO 4 \u003d SnSO 4 + H 2 O,
SnO + 2KOH + H 2 O \u003d K 2,
ZnO + 2KOH \u003d K 2 ZnO 2 + H 2 O.
Amphoteric oxides include: ZnO, BeO, SnO, PbO, Al 2 O 3, Cr 2 O 3, Fe 2 O 3, Sb 2 O 3, MnO 2 and etc.
It should be noted that, in accordance with the change in the chemical nature of the elements in the periodic system of elements (from metals to nonmetals), the chemical properties of the compounds also naturally change, in particular, the acid-base activity of their oxides. So, in the case of higher oxides of elements, there are 3 periods in the series: Na 2 O, MgO, Al 2 O 3, SiO 2, P 2 O 5, SO 3, Cl 2 O 7 - as the degree of polarity decreases E-O communications(DEO decreases; the negative effective charge of the oxygen atom decreases) the basic ones are weakened and the acidic properties of oxides increase: Na 2 O, MgO - basic oxides; Al 2 O 3 - amphoteric; SiO 2 , P 2 O 5 , SO 3 , Cl 2 O 7 - acidic oxides (from left to right, the acidic nature of the oxides increases).
Methods for obtaining oxides:
1. Interaction of simple substances with oxygen (oxidation):
4Fe + 3O 2 \u003d 2Fe 2 O 3,
S + O 2 \u003d SO 2.
2. Combustion of complex substances:
CH 4 + 2O 2 \u003d CO 2 + 2H 2 O,
2SO 2 + O 2 \u003d 2SO 3.
3. Thermal decomposition of salts, bases, acids:
CaCO 3 ® CaO + CO 2,
Cd (OH) 2 ® CdO + H 2 O,
H 2 SO 4 ® SO 3 + H 2 O.
Nomenclature of oxides. The names of oxides are built from the word "oxide" and the name of the element in the genitive case, which is connected to oxygen atoms. If an element forms several oxides, then its oxidation state (s.o.) is indicated in brackets in Roman numerals, while the c sign. O. not specified. For example, MnO 2 is manganese (IV) oxide, MnO is manganese (II) oxide. If an element forms one oxide, then its s. O. not given: Na 2 O - sodium oxide.
Sometimes the prefixes di-, tri-, tetra-, etc. are found in the names of oxides. They mean that in the molecule of this oxide there are 2,3,4 per atom of the element, etc. oxygen atom, for example, CO 2 - carbon dioxide, etc.
Hydroxides
Among multielement compounds, an important group is hydroxides are complex substances containing hydroxo groups OH. Some of them (basic hydroxides) exhibit the properties of bases - NaOH, Ba(OH) 2, etc.; others (acid hydroxides) exhibit the properties of acids - HNO 3, H 3 PO 4, etc.; there are also amphoteric hydroxides that, depending on the conditions, can exhibit both basic and acidic properties - Zn (OH) 2, Al (OH) 3, etc.
The properties and nature of hydroxides also depend on the charge of the nucleus of the central atom (symbol E) and its radius, i.e. on the strength and polarity of the E - O and O - H bonds.
If the binding energy E O - H<< E Э - О, то диссоциация гидроксида протекает по кислотному типу, т. е. разрушается связь О – Н.
EON Û EO - + H +
If E O-H >> E E - O, then the dissociation of the hydroxide proceeds according to the main type, i.e., the E - O bond is destroyed
EOH Û E + + OH -
If the energies of the bonds O - H and E - O are close or equal, then the dissociation of the hydroxide can proceed simultaneously in both directions. In this case we are talking about amphoteric hydroxides:
E n+ + nOH - Û E(OH) n = H n EO n Û nH + + EO n n-
In accordance with the change in the chemical nature of elements in the periodic system of elements, the acid-base activity of their hydroxides naturally changes: from basic hydroxides through amphoteric to acidic. For example, for higher hydroxides of elements there are 3 periods:
NaOH, Mg(OH) 2 - bases (from left to right, the basic properties weaken);
Al(OH) 3 - amphoteric hydroxide;
H 2 SiO 3, H 3 PO 4, H 2 SO 4, HClO 4 - acids (from left to right, the strength of acids increases).
Metal hydroxides are bases. The more pronounced the metallic properties of an element, the more pronounced are the basic properties of the corresponding metal hydroxide in the highest s.d. Non-metal hydroxides exhibit acidic properties. The more pronounced the non-metallic properties of an element, the stronger the acidic properties of the corresponding hydroxide.
acids
Acids are substances that dissociate in solutions with the formation of hydrogen cations and anions of the acid residue (from the standpoint of the theory of electrolytic dissociation).
Acids are classified according to their strength (according to the ability to electrolytic dissociation - into strong and weak), by basicity (according to the number of hydrogen atoms in the acid molecule that can be replaced by metal atoms to form a salt - into monobasic, dibasic, tribasic), by the presence or absence of oxygen as part of the acid (on oxygen-containing and anoxic). For example, nitric acid HNO 3 is a strong, monobasic, oxygen-containing acid; hydrosulfide acid H 2 S is a weak, dibasic, oxygen-free acid.
Chemical properties acids:
1. Interaction with bases to form salt and water (neutralization reaction):
H 2 SO 4 + Cu (OH) 2 \u003d CuSO 4 + 2H 2 O.
2. Interaction with basic and amphoteric oxides to form salts and water:
2HNO 3 + MgO \u003d Mg (NO 3) 2 + H 2 O,
H 2 SO 4 + ZnO \u003d ZnSO 4 + H 2 O.
3. Interaction with metals. Metals standing in the “Series of stresses” up to hydrogen displace hydrogen from acid solutions (except for nitric and concentrated sulfuric acids); this produces a salt:
Zn + 2HCl \u003d ZnCl 2 + H 2.
Metals that are in the “Series of Voltages” after hydrogen do not displace hydrogen from acid solutions
For the interaction of metals with nitric and concentrated sulfuric acids, see Section 11.
4. Some acids decompose when heated:
H 2 SiO 3 H 2 O + SiO 2.
5. Less volatile acids displace more volatile acids from their salts:
H 2 SO 4 conc + NaCl tv \u003d NaHSO 4 + HCl.
6. Stronger acids displace weaker acids from solutions of their salts:
2HCl + Na 2 CO 3 \u003d 2NaCl + H 2 O + CO 2
Nomenclature of acids. The names of oxygen-free acids are made up by adding the suffix - O-, ending hydrogen and the word acid. For example, HCl is hydrochloric acid, H 2 S is hydrosulfide acid, HCN is hydrocyanic acid.
The names of oxygen-containing acids are also formed from the Russian name of the acid-forming element with the addition of the appropriate suffixes, endings and the word "acid". In this case, the name of the acid in which the element is in the highest oxidation state ends in - naya or - new; for example, H 2 SO 4 is sulfuric acid, HClO 4 is perchloric acid, H 3 AsO 4 is arsenic acid. With a decrease in the oxidation state of the acid-forming element, the endings change in the following sequence: - oval(HClO 3 - chloric acid), true(HClO 2 - chlorous acid), - ovate(HClO - hypochlorous acid). If the element forms acids, being in only two oxidation states, then the name of the acid corresponding to the lower oxidation state of the element has the ending true(HNO 3 - nitric acid, HNO 2 - nitrous acid).
In some cases, a different number of water molecules can join one oxide molecule (i.e., an element in the same oxidation state forms several acids containing one atom of this element each). Then an acid with a high water content is denoted by the prefix ortho- , and an acid with a smaller number of water molecules is denoted by the prefix meta- . For example:
P 2 O 5 + H 2 O \u003d 2HPO 3 - metaphosphoric acid;
P 2 O 5 + 3H 2 O \u003d 2H 3 PO 4 - phosphoric acid.
Foundations
The grounds from the standpoint of the theory of electrolytic dissociation are substances that dissociate in solutions with the formation of hydroxide - ions OH ‾ and metal ions (with the exception of NH 4 OH).
Bases are classified according to their strength.(according to the ability to electrolytic dissociation - into strong and weak), by acidity(according to the number of hydroxo groups in the molecule that can be replaced by acidic residues - by one-acid, two-acid, etc.), by solubility(for soluble bases - alkalis and insoluble). For example: NaOH is a strong, single acid base, soluble (alkali); Cu(OH) 2 is a weak, diacid, insoluble base. Soluble bases (alkalis) include hydroxides of alkali and alkaline earth metals. All alkalis are strong bases.
Chemical properties of bases:
1. Interaction with acids:
Ca (OH) 2 + H 2 SO 4 \u003d CaSO 4 ¯ + H 2 O.
2. Interaction with acid oxides:
3. Interaction with amphoteric oxides:
2KOH + Al 2 O 3 \u003d 2KAlO 2 + H 2 O 1,
2KOH + SnO + H 2 O = K 2 [Sn(OH) 4].
4. Interaction with amphoteric bases:
2NaOH + Zn(OH) 2 = Na 2 ZnO 2 + 2H 2 O2,
2NaOH + Zn(OH) 2 = Na 2 [Zn(OH) 4 ]3.
5. Thermal decomposition of bases with the formation of oxides and water:
Ca (OH) 2 \u003d CaO + H 2 O.
Alkali metal hydroxides do not decompose when heated.
6. Interaction with amphoteric metals (Zn, Al, Pb, Sn, Be):
Zn + 2NaOH + 2H 2 O \u003d Na 2 + H 2
amphoteric hydroxides. Amphoteric hydroxides (hydrates of amphoteric oxides) are capable of dissociating in aqueous solutions both as acids and as bases. For example:
ZnO 2 2- + 2H + Û Zn(OH) 2 Û Zn 2+ + 2OH .
Therefore, they have amphoteric properties, i.e. can interact with both acids and bases:
Zn(OH) 2 + 2HCl = ZnCl 2 + 2H 2 O,
Sn(OH) 2 + 2NaOH = Na 2 [Sn(OH) 4].
Base nomenclature. The names of the bases are built from the word “ hydroxide” and the name of the metal in the genitive case, indicating its degree of oxidation in brackets in Roman numerals, if this is a variable value. Sometimes a prefix from the Greek numeral is added to the word hydroxide, indicating the number of hydroxo groups in the base molecule. For example: KOH - potassium hydroxide; Al(OH) 3 - aluminum hydroxide (aluminum trihydroxide); Cr (OH) 2 - chromium (II) hydroxide (chromium dihydroxide).
salt
From the point of view of the theory of electrolytic dissociation Salts are substances that dissociate in solutions or melts to form positively charged ions other than hydrogen ions and negatively charged ions other than hydroxide ions.
Salts are usually considered as products of complete or partial replacement of hydrogen atoms in an acid molecule by metal atoms or products of complete or partial replacement of hydroxo groups in a base molecule by acidic residues. With complete substitution, medium (or normal) salts are obtained, dissociating in solutions or in melts with the formation of metal cations and anions of acid residues (ammonium salts are an exception). With incomplete substitution of the hydrogen of the acid, acidic salts are obtained, with incomplete substitution of the hydroxo groups of the base, basic salts are obtained. The dissociation of acid and basic salts is discussed in section 8. Acid salts can only be formed by polybasic acids (H 2 SO 4, H 2 SO 3, H 2 S, H 3 PO 4, etc.), and basic salts can be formed by polyacid bases (Mg (OH) 2, Ca (OH) 2, Al (OH) 3, etc.).
Examples of salt formation:
Ca (OH) 2 + H 2 SO 4 \u003d CaSO 4 + 2H 2 O,
CaSO 4 (calcium sulfate) - normal (medium) salt;
H 2 SO 4 + NaOH \u003d NaHSO 4 + H 2 O,
NaHSO 4 (sodium hydrogen sulfate) - an acid salt obtained as a result of a lack of a taken base;
Cu (OH) 2 + HCl \u003d CuOHCl + H 2 O,
CuOHCl (hydroxycopper (II) chloride) is a basic salt obtained as a result of a lack of taken acid.
Chemical properties of salts:
I. Salts enter into ion exchange reactions if a precipitate forms, a weak electrolyte, or gas is released:
salts react with alkalis, the metal cations of which correspond to insoluble bases:
CuSO 4 + 2NaOH \u003d Na 2 SO 4 + Cu (OH) 2 ↓;
Salts react with acids:
a) whose cations form an insoluble salt with the anion of the new acid:
BaCl 2 + H 2 SO 4 = BaSO 4 ↓ + 2HCl;
b) the anions of which correspond to an unstable carbonic or some volatile acid (in the latter case, the reaction is carried out between a solid salt and a concentrated acid):
Na 2 CO 3 + 2HCl \u003d 2NaCl + H 2 O + CO 2,
NaCl tv + H 2 SO 4 conc \u003d NaHSO 4 + HCl;
c) the anions of which correspond to a sparingly soluble acid:
Na 2 SiO 3 + 2HCl = H 2 SiO 3 ↓ + 2NaCl;
d) whose anions correspond to a weak acid:
2CH 3 COONa + H 2 SO 4 = Na 2 SO 4 + 2CH 3 COOH;
salts interact with each other if one of the new salts formed is insoluble or decomposes (completely hydrolyzes) with the release of gas or precipitate:
AgNO 3 + NaCl \u003d NaNO 3 + AgCl ↓,
2AlCl 3 + 3Na 2 CO 3 + 3H 2 O \u003d 2Al (OH) 3 ↓ + 6NaCl + 3CO 2.
II. Salts can interact with metals if the metal to which the salt cation corresponds is in the “Series of voltages” to the right of the reacting free metal (the more active metal displaces the less active metal from the solution of its salt):
Zn + CuSO 4 \u003d ZnSO 4 + Cu.
III. Some salts decompose when heated:
CaCO 3 \u003d CaO + CO 2.
IV. Some salts are able to react with water and form crystalline hydrates:
CuSO 4 + 5H 2 O \u003d CuSO 4 ٭ 5H 2 O ΔH<0
white blue blue
The release of heat and color change are signs of chemical reactions.
V. Salts undergo hydrolysis. This process will be described in detail in section 8.10.
VI. The chemical properties of acidic and basic salts differ from the properties of medium salts in that acidic salts also enter into all reactions characteristic of acids, and basic salts enter into all reactions characteristic of bases. For example:
NaHSO 4 + NaOH \u003d Na 2 SO 4 + H 2 O,
MgOHCl + HCl \u003d MgCl 2 + H 2 O.
Getting salts:
1. Interaction of basic oxide with acid:
CuO + H 2 SO 4 \u003d CuSO 4 + H 2 O.
2. Interaction of a metal with a salt of another metal:
Mg + ZnCl 2 = MgCl 2 + Zn.
3. Interaction of metal with acid:
Mg + 2HCl \u003d MgCl 2 + H 2.
4. Interaction of a base with an acid oxide:
Ca (OH) 2 + CO 2 \u003d CaCO 3 + H 2 O.
5. Interaction of a base with an acid:
Fe(OH) 3 + 3HCl= FeCl 3 + 3H 2 O.
6. Interaction of salt with base:
FeCl 2 + 2KOH \u003d Fe (OH) 2 ¯ + 2KCl.
7. Interaction of two salts:
Ba(NO 3) 2 + K 2 SO 4 = BaSO 4 ¯ + 2KNO 3 .
8. Interaction of metal with non-metal:
9. Interaction of acid with salt:
CaCO 3 + 2HCl \u003d CaCl 2 + H 2 O + CO 2.
10. Interaction of acidic and basic oxides:
CaO + CO 2 \u003d CaCO 3.
Salt nomenclature. According to international nomenclature rules, the names of medium salts are formed from the name of the acid residue in the nominative case and the name of the metal in the genitive case, indicating its degree of oxidation in brackets in Roman numerals (if this is a variable value). The name of the acid residue consists of the root of the Latin name of the acid-forming element, the corresponding ending and, in some cases, the prefix.
Acidic residues of oxygen-free acids end up id. For example: SnS - tin (II) sulfide, Na 2 Se - sodium selenide. The endings of the names of acid residues of oxygen-containing acids depend on the degree of oxidation of the acid-forming element. For its highest oxidation state (“-naya” or “-ovaya” acid), the ending is used -at. For example, salts of nitric acid HNO 3 are called nitrates, sulfuric acid H 2 SO 4 - sulfates, chromic acid H 2 CrO 4 - chromates. For a lower oxidation state of an acid-forming element (“...pure acid”), the ending is used it. So, salts of nitrous acid HNO 2 are called nitrites, sulfurous acid H 2 SO 3 - sulfites. If there is an acid with an even lower oxidation state of the acid-forming element (“-woolly acid”), its anion receives the prefix hypo- and ending - it. For example, salts of hypochlorous acid HClO are called hypochlorites.
Salts of some acids, in accordance with the historical tradition, have retained names that differ from the systematic ones. So, salts of permanganic acid HMnO 4 are called permanganates, perchloric acid HClO 4 - perchlorates, iodic acid HIO 4 - periodates. Salts of permanganic acid H 2 MnO 4 , chloric HClO 3 and iodic HIO 3 acids are called manganates, chlorates and iodates, respectively.
The names of acidic and basic salts are formed according to the same general rules as the names of medium salts. In this case, the name of the acid salt anion is supplied with the prefix hydro-, indicating the presence of unsubstituted hydrogen atoms; the number of unsubstituted hydrogen atoms is indicated by Greek numeral prefixes. For example, Na 2 HPO 4 is sodium hydrogen phosphate, NaH 2 PO 4 is sodium dihydrogen phosphate.
Similarly, the base salt cation receives the prefix hydroxo- indicating the presence of unsubstituted hydroxo groups. The number of hydroxyl groups is indicated by Greek numerals. For example, Cr(OH) 2 NO 3 is dihydroxochrome (III) nitrate.
The names of the most important acids and their acidic residues are given in Table. 4.1.
Table 4.1
Names and formulas of acids and their acid residues
Continuation of the table. 4.1
Chemicals can be divided into two unequal groups: simple and complex.
Simple substances consist of atoms of one element (O 2, P 4).
Complex Substances consist of atoms of two or more elements (CaO, H 3 PO 4).
Simple substances can be divided into metals And nonmetals.
Metals- These are simple substances in which atoms are interconnected by a metallic chemical bond. Metals tend to donate electrons and are characterized by metallic properties (metallic luster, high electrical and thermal conductivity, plasticity, etc.).
non-metals – These are simple substances in which atoms are connected by covalent (or intermolecular) bonds. Nonmetals tend to accept or attract electrons. Non-metallic properties are the ability to accept or attract electrons.
All elements in the Periodic Table of Chemical Elements (PSCE) are located either in main subgroup, or V side. In various forms of short-period PSCE, the main and secondary subgroups are located differently. There is a simple way that will allow you to quickly and reliably determine which subgroup an element belongs to. The fact is that all the elements of the second period are located in the main subgroup. Those elements that are located in the cell exactly below the elements of the second period (to the right or left) belong to the main subgroup. The rest - to the side.
For example , in the periodic table, which is used in the exam in chemistry, element number 32, gallium, is located in the cell on the right, just below its corresponding element of the second period, boron. Therefore, gallium belongs to the main subgroup. But scandium, element number 21, is located in the cell on the left. Therefore, scandium belongs to a side subgroup.
Non-metals are located in main subgroups, in the upper right corner of the PSCE. All metals are elements of secondary subgroups And elements of the main subgroups located in the lower left part of the PSCE. Metals and non-metals are usually separated by drawing a conditional line from beryllium to astatine. The figure shows the exact division into metals and non-metals. Colored non-metals.
The main classes of complex substances are oxides, hydroxides, salt.
oxides- these are complex substances that consist of atoms of two elements, one of which is oxygen, which has an oxidation state of -2.
Depending on the second element, oxides exhibit different chemical properties. Some oxides correspond to hydroxides (salt-forming oxides), and some do not (non-salt-forming).
Salt-forming oxides divided into basic, amphoteric and acidic.
Basic oxides are oxides that exhibit characteristic basic properties. These include oxides formed by atoms metals co oxidation state +1 and +2 . For example, lithium oxide Li 2 O, iron oxide (II) FeO.
Acid oxides are oxides that exhibit acidic properties. These include oxides formed by atoms metals with an oxidation state of +5, +6 and +7 , as well as non-metal atoms with any degree of oxidation . For example, chlorine oxide (I) Cl 2 O, chromium oxide (VI) CrO 3.
Amphoteric oxides are oxides that exhibit both basic and acidic properties. These are oxides metals with an oxidation state of +3 and +4 , as well as four oxides with an oxidation state of +2: ZnO, PbO, SnO and BeO .
Non-salt-forming oxides do not exhibit characteristic basic or acidic properties; hydroxides do not correspond to them. Four oxides are classified as non-salt-forming: CO, NO, N 2 O and SiO .
There are also oxides similar to salts, i.e. salty (double).
Double oxides are some oxides formed by an element with different oxidation states. For example, magnetite (magnetic iron ore) FeO·Fe 2 O 3 .
Algorithm for determining the type of oxide: at first determine which element forms an oxide - metal or non-metal. If it is a metal, then we determine the degree of oxidation, then we determine the type of oxide. If it is a non-metal, then the oxide is acidic (if this is not an exception).
Hydroxides- these are complex substances, which include the E-O-H group. Hydroxides include bases, amphoteric hydroxides, and oxygenated acids.
Each salt-forming oxide corresponds to a hydroxide:
basic oxide corresponds to hydroxide base ,
acid oxide corresponds to hydroxide acid ,
amphoteric oxide corresponds amphoteric hydroxide .
For example, chromium oxide (II) CrO - basic, it corresponds to the hydroxide base. The hydroxide formula is easy to obtain by simply adding the hydroxide group OH: Cr(OH) 2 to the metal.
Chromium oxide (VI) is acidic, it corresponds to the hydroxide acid H 2 CrO 4, and the acid residue is the chromate ion CrO 4 2-.
If all indices are multiples of 2, then we divide all indices by 2.
For example: N 2 O 5 + H 2 O → H 2 N 2 O 6, divide by 2, we get HNO 3. So we get meta formula acids. If we add one more water molecule, we get ortho formula acids.
For example: oxide P 2 O 5 , meta form: HPO 3 . Add water, ortho form: H 3 PO 4 . The ortho form is stable in phosphorus and arsenic.
Chromium oxide (III) - Cr 2 O 3 - amphoteric, it corresponds to an amphoteric hydroxide, which can act both as a base and as an acid: Cr (OH) 3 \u003d HCrO 2, chromite acid residue: CrO 2 -.
The relationship of oxides and hydroxides:
Foundations(basic hydroxides) are complex substances that, when dissociated in aqueous solutions as anions (negative ions), form only hydroxide ions OH -.
Bases can be divided into water-soluble ( alkalis ), insolublein water, and spontaneouslydecaying .
TO decomposing in water (unsustainable) bases include ammonium hydroxide, silver (I) hydroxide, copper (I) hydroxide. In an aqueous solution, such compounds decompose almost irreversibly:
NH 4 OH → NH 3 + H 2 O
2AgOH → Ag 2 O + H 2 O
2CuOH → Cu 2 O + H 2 O
Bases with one OH group - single acid(For example, NaOH), with two - two-acid(Ca(OH) 2) and with three triacid(Fe(OH) 3).
acids- these are complex substances that, when dissociated in aqueous solutions, form only hydronium ions H 3 O + (H +) as cations. Acids are made up of hydrogen H+ and an acid residue.
According to the number of hydrogen atoms that can be replaced by metals, acids are divided into monobasic (HNO 3), dibasic(H 2 SO 4), tribasic (H 3 PO 4), etc.
Acids can also be divided into strong and weak.
Strong acids. These include:
- Anoxic acids: HCl, HBr, HI. The remaining anoxic acids are usually weak.
- Some higher oxygenated acids: H 2 SO 4 , HNO 3 , HClO 4 and etc.
Weak acids . These include:
- Weak and soluble acids : This H3PO4, CH3COOH, HF and etc.
- Volatile or unstable acids : H 2 S— gas; H2CO3 H 2 CO 3 → H 2 O + CO 2; H2SO3- decomposes into water and oxide: H 2 SO 3 → H 2 O + SO 2.
- acids insoluble in water : H2SiO3, H3BO3 and others.
To determine whether the acid in front of you is strong, or weak, allows a simple trick. We subtract the number of H atoms from the number of O atoms in the acid. If we get the number 2 or 3, then the acid strong. If 1 or 0 - then acid weak.
salt- complex substances consisting of a metal cation (or metal-like cations, for example, ammonium ion NH 4 +) and an anion of an acid residue. Salts are also called substances that can be obtained by the interaction of acids and bases with the release of water.
Considering salts as reaction products of acid and base, then the salts are divided by medium , sour And main .
Medium salt are the products of complete replacement of hydrogen cations in acid by metal cations ( For example , Na 2 CO 3 , K 3 PO 4).
Sour salt are products of incomplete replacement of hydrogen cations in acid by metal cations ( For example , NaHCO 3 , K 2 HPO 4).
Main salt are the products of incomplete substitution of hydroxo groups of the base with anions of the acid residues of the acid ( For example, malachite (CuOH) 2 CO 3).
According to the number of cations and anions salts are divided into:
Simple salts - consisting of a cation of the same type and an anion of the same type ( For example, calcium chloride CaCl2).
double salts are salts consisting of two or more different cations and an anion of the same type ( For example, potassium alum - KAl(SO 4) 2).
mixed salts are salts consisting of a cation of the same type and two or more anions of a different type ( For example, calcium chloride-hypochlorite Ca(OCl)Cl).
According to the structural features, there are also hydrated salt and complex salt.
Hydrate salts (crystalline hydrates) - these are salts, which include molecules of crystallization water ( For example, sodium sulfate decahydrate Na 2 SO 4 10 H 2 O).
Complex salts are salts containing a complex cation or complex anion ( K 3 , (OH) 2).
In addition to the main classes of inorganic compounds, there are a large number of others. For example, binary compounds of elements with hydrogen.
Hydrogen compounds - These are complex substances consisting of two elements, one of which is hydrogen. Hydrogen forms salt-like hydrides and volatile hydrogen compounds.
Salt hydrides EN x are compounds of metals of IA, IIA groups and aluminum with hydrogen. The oxidation state of hydrogen is -1. For example, sodium hydride NaH.
Volatile hydrogen compounds H x E are compounds of non-metals with hydrogen, in which the oxidation state of hydrogen is +1. For example, ammonia NH3, phosphine PH 3.
Salt-forming oxides:
1). Basic oxides are oxides that correspond to bases. The main oxides include oxides of metals of groups 1 and 2, as well as metals of secondary subgroups with valence I and II (except for ZnO - zinc oxide and BeO - beryllium oxide): lithium oxide Li 2 O; sodium oxide Na 2 O; potassium oxide K 2 O; copper oxide CuO; silver oxide Ag2O; magnesium oxide MgO; calcium oxide CaO; strontium oxide SrO; cesium oxide Cs 2 O; mercury oxide (2) HgO; rubidium oxide Rb 2 O; iron oxide (2) FeO; chromium oxide CrO; nickel oxide NiO.
2). Acid oxides are oxides to which acids correspond. Acid oxides include oxides of non-metals (except for non-salt-forming - indifferent), as well as oxides of metals of secondary subgroups with valence from V to VII:
carbon monoxide(IV) CO 2 ; sulfur oxide (IV) SO 2 ; sulfur oxide (VI) SO 3 ; silicon(IV) oxide SiO 2 ; phosphorus(V) oxide P 2 O 5 ; chromium(VI) oxide CrO 3 ; manganese(VII) oxide Mn 2 O 7 ; nitric oxide NO 2 ; chlorine oxides Cl 2 O 5 and Cl 2 O 3 .
3). Amphoteric oxides are oxides corresponding to bases and acids. Formed by transition metals. Metals in amphoteric oxides usually exhibit an oxidation state of +3 to +4, with the exception of ZnO, BeO, SnO, PbO: zinc oxide ZnO; chromium(III) oxide Cr 2 O 3 ; aluminum oxide Al 2 O 3 ; tin(II) oxide SnO; tin(IV) oxide SnO 2 ; lead(II) oxide PbO; lead(IV) oxide PbO 2 ; titanium(IV) oxide TiO 2 ; manganese(IV) oxide MnO 2 ; iron(III) oxide Fe 2 O 3 ; beryllium oxide BeO.
Non-salt-forming oxides
1). Non-salt-forming oxides are oxides that are indifferent to acids and bases. These include oxides of non-metals with valence I and II:
carbon monoxide(II) CO; nitric oxide (II) NO; nitric oxide(I) N 2 O; silicon(II) oxide SiO, sulfur(I) oxide S 2 O; hydrogen oxide H 2 O.
Foundations. Base classification
Bases are called hydroxides, which dissociate (decompose) into a hydroxyl group and a positively charged cation. The general formula of bases is E(OH)m, where m is the oxidation state of the metal.
Classification of bases by strength:
1). Strong bases.
Bases soluble in water are called alkalis:
NaOH - sodium hydroxide (caustic soda); KOH - potassium hydroxide (caustic potash); LiOH - lithium hydroxide; Ba(OH) 2 - barium hydroxide; Ca (OH) 2 - calcium hydroxide (slaked lime).
2). Weak grounds:
Mg(OH) 2 - magnesium hydroxide; Fe (OH) 2 - iron (II) hydroxide; Zn(OH) 2 - zinc hydroxide; NH 4 OH - ammonium hydroxide; A1 (OH) 3 - aluminum hydroxide; Fe (OH) 3 - iron (III) hydroxide, etc. (most metal hydroxides).
Classification of bases by solubility
More acceptable is the classification of bases according to their solubility in water.
1) Soluble bases. alkalis are bases soluble in water. Alkalis include hydroxides of alkali and alkaline earth metals: LiOH, NaOH, KOH, RbOH, CsOH, CaOH) 2, Sr(OH) 2, Ba(OH) 2.
2). Insoluble bases- these are the so-called amphoteric hydroxides, which, when interacting with acids, act as bases, and with alkali - as acids.
Classification of bases according to the number of hydroxyl groups (OH):
1). Single acid bases (n = 1)- this is a base, which includes one group - (OH): LiOH, KOH, NaOH, NH4OH.
2). Diacid bases - (n = 2)- this is a base, which includes two groups - (OH): Ba (OH) 2, Mg (OH) 2, Zn (OH) 2, Fe (OH) 2.
3). Triacid bases - (n = 3)- this is a base, which includes three groups - (OH): Fe (OH) 3, A1 (OH) 3, etc.
Acids. Acid classification
Acid is a complex substance in the molecule of which there are one or more hydrogen atoms and an acid residue. Acids are classified according to the following criteria: a) by the presence or absence of oxygen in the molecule and b) by the number of hydrogen atoms.
a) Classification of acids according to the presence or absence of oxygen in the molecule:
1). Oxygen-containing acids: H 2 SO 4 - sulfuric acid; H 2 SO 3 - sulfurous acid; HNO 3 - nitric acid; H 3 PO 4 - phosphoric acid; H 2 CO 3 - carbonic acid; H 2 SiO 3 - silicic acid; HClO 4 - perchloric acid; HClO 3 - hydrogen trioxochlorate (V) (chloric acid); HClO 2 - hydrogen dioxochlorate (III) (chlorous acid); HClO - hydrogen oxochlorate(I) (hypochlorous acid); H 2 Cr 2 O 7 - heptaoxodichromate (VI) dihydrogen (dichromic acid); H 2 S 4 O 6 - dihydrogen hexaoxotetrasulfate (tetrathionic acid); H 2 B 4 O 6 - hexaoxotetraborate dihydrogen (tetrametaboric acid); H is hydrogen hexahydroxoantibate(V); H 3 PO 3 S - thiophosphoric acid; HbSO 3 S - thiosulfuric acid; H 3 PO 3 - phosphorous (phosphonic) acid.
2). Anoxic acids: HF - hydrofluoric acid; HCl - hydrochloric acid (hydrochloric acid); HBr - hydrobromic acid; HI - hydroiodic acid; H 2 S - hydrosulfide acid; HAuCl4 - hydrogen tetrachloroaurate(III) (hydrochloric acid); HSCN - thiocyanate; HN3 - azidic acid.
b) Classification of acids according to the number of hydrogen atoms:
1). Monobasic acids- these are acids, which include one ion (H +): HNO 3 - nitric acid; HF - hydrofluoric acid; HCl - hydrochloric acid; HBr - hydrobromic acid; HI - hydroiodic acid; HClO 4 - perchloric acid; HClO 3 - hydrogen trioxochlorate (V) (chloric acid); HClO 2 - hydrogen dioxochlorate (III) (chlorous acid); HClO - hydrogen oxochlorate(I) (hypochlorous acid); HAuCl 4 - tetrachloroaurate(III) hydrogen (auric acid); H is hydrogen hexahydroxoantibate(V); HSCN - thiocyanate.
2). Dibasic acids- these are acids, which include two ions (H +): H 2 SO 4 - sulfuric acid; H 2 SO 3 - sulfurous acid; H 2 S - hydrosulfide acid; H 2 CO 3 - carbonic acid; H 2 SiO 3 - silicic acid; H 2 Cr 2 O 7 - heptaoxodichromate (VI) dihydrogen (dichromic acid); H 2 S 4 O 6 - dihydrogen hexaoxotetrasulfate (tetrathionic acid); H 2 B 4 O 6 - hexaoxotetraborate dihydrogen (tetrametaboric acid); H 2 SO 3 S - thiosulfuric acid.
3). Tribasic acids- these are acids, which include three ions (H +): H 3 PO 4 - phosphoric acid; H3BO3 - boric acid; H 3 AsO 4 - arsenic acid; H 3 PO 3 S - thiophosphoric acid; H 3 AlO 3 - orthoaluminum acid; H 3 PO 3 - phosphorous (phosphonic) acid.
4). Polybasic (polybasic) acids- these are acids, which include four or more ions (H +): H 4 SiO 4 - orthosilicic acid; H 4 CO 4 - orthocarbonic acid; H 4 P 2 O 7 - diphosphoric (pyrophosphoric) acid; H 6 P 6 O 18 - hexaphosphoric acid; H 6 TeO 6 - telluric acid.
Other classifications of acids:
Acid strength:
Strong acids - dissociate almost completely, dissociation constants greater than 1 .
10 -3 (HNO 3); HCl; H2SO4);
Weak acids - dissociation constant less than 1 .
10 -3 (acetic acid Kd = 1.7 .
10 -5).
For sustainability:
Resistant acids (H 2 SO 4);
Unstable acids (H 2 CO 3).
By belonging to the classes of chemical compounds:
Inorganic acids: (HBr); (H2SO4);
Organic acids: (HCOOH,CH3COOH).
By volatility:
Volatile acids: (HNO 3 ,H 2 S);
Non-volatile acids: (H 2 SO 4).
By solubility in water:
Soluble acids (H 2 SO 4);
Insoluble acids (H 2 SiO 3).
Salt.
Salts are substances in which metal atoms are bonded to acidic residues. An exception are ammonium salts, in which not metal atoms are bound to acidic residues, but NH4+ particles, for example, (NH4)2SO4 - ammonium sulfate.
Salt classification:
1). Medium salts.
Medium salts- these are complex substances that dissociate in aqueous solutions into metal cations and anions of acid residues, i.e. they are products of substitution of all hydrogen cations in acid molecules for metal cations (Na 2 CO 3 , K 3 PO 4).
2). Acid salts.
Acid salts- these are products of partial replacement of hydrogen cations in acids with metal cations (NaHCO 3, KH 2 PO 4, K 2 HPO 4). They are formed when a base is neutralized with an excess of an acid (that is, under conditions of a lack of a base or an excess of an acid).
3). Basic salts.
Basic salts- these are products of incomplete replacement of the hydroxo groups of the base (OH -) with acid residues (CuOH) 2 CO 3, CoNO 3 (OH). They are formed under conditions of excess base or lack of acid.
4). complex salts.
Complex salts- salts having complex cations or anions in which the bond is formed by the donor-acceptor mechanism. Complex ions, combining with other ions, form complex salts, for example, K 4, Cl, K 2, (Na 2), etc.
Classification of salts according to the number of cations and anions present in the structure
The following types of salts are distinguished:
1). Simple salts.
Simple salts- these are salts consisting of one type of cations and one type of anions (NaCl).
2). Double salts.
double salts are salts containing two different types of cations. examples of double salts are (KAl(SO 4) 2 .
12H 2 O) (potassium alum), KAl (SO4) 2 (aluminum-potassium sulfate), MgK 2 (SO4) 2, AgK (CN) 2. Double salts exist only in solid form.
3). Mixed salts.
mixed salts are salts that contain two different anions (Ca (OCl) Cl), Fe (NH 4) 2 (SO 4) 2 [diammonium-iron (II) sulfate], LiAl (SiO 3) 2 (aluminum metasilicate- lithium), Ca (ClO) Cl (calcium chloride-hypochlorite), Na 3 CO 3 (HCO 3) (sodium bicarbonate carbonate), Na 2 IO 3 (NO 3) (sodium nitrate-iodate)
4). Hydrated salts (crystalline hydrates).
Hydrate salts or crystalline hydrates- these are salts, which include molecules of crystallization water, for example, Na 2 SO 4 10 H 2 O, CaSO 4 ·
2H 2 O (gypsum), MgCl 2 ·
KCl ·
6H 2 O (carnallite), CuSO 4 ·
5H 2 O (copper sulfate), FeSO 4 ·
7H 2 O (ferrous sulfate), Na 2 CO 3 ·
10H 2 O (crystalline soda).
5). internal salts.
internal salts- these are salts that are formed by bipolar ions, that is, molecules containing both positively charged and negatively charged atom (+) NH 3 -CH 2 -COO (-) (bipolar ion of the amino acid glycine), (+) NH 3 -C 6 H 4 -SO 3 (-) (sulfanilic acid or taurine). Taurine- sulfonic acid formed in the body from the amino acid cysteine.
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