Metal and hydroxyl group (OH). For example, sodium hydroxide - NaOH, calcium hydroxide - Ca(OH) 2 , barium hydroxide - Ba(OH) 2, etc.

Preparation of hydroxides.

1. Exchange reaction:

CaSO 4 + 2NaOH = Ca(OH) 2 + Na 2 SO 4,

2. Electrolysis aqueous solutions salts:

2KCl + 2H 2 O = 2KOH + H 2 + Cl 2,

3. Interaction of alkali and alkaline earth metals or their oxides with water:

K+2H 2 O = 2 KOH + H 2 ,

Chemical properties of hydroxides.

1. Hydroxides are alkaline in nature.

2. Hydroxides dissolves in water (alkali) and is insoluble. For example, KOH- dissolves in water, and Ca(OH) 2 - slightly soluble, has a solution white. Metals of group 1 of the periodic table D.I. Mendeleev gives soluble bases (hydroxides).

3. Hydroxides decompose when heated:

Cu(OH) 2 = CuO + H 2 O.

4. Alkalis react with acidic and amphoteric oxides:

2KOH + CO 2 = K 2 CO 3 + H 2 O.

5. Alkalis can react with some non-metals in different ways at different temperatures:

NaOH + Cl 2 = NaCl + NaOCl + H 2 O(cold),

NaOH + 3 Cl 2 = 5 NaCl + NaClO 3 + 3 H 2 O(heat).

6. Interact with acids:

KOH + HNO3 = KNO 3 + H 2 O.

Alkali metal hydroxides - under normal conditions, are solid white crystalline substances, hygroscopic, soapy to the touch, very soluble in water (their dissolution is an exothermic process), fusible. Hydroxides alkaline earth metals Ca(OH) 2, Sr(OH) 2, Ba(OH) 2) are white powdery substances, much less soluble in water compared to alkali metal hydroxides. Water-insoluble bases usually form as gel-like precipitates that decompose during storage. For example, Cu(OH) 2 is a blue gelatinous precipitate.

3.1.4 Chemical properties of bases.

The properties of bases are determined by the presence of OH – ions. There are differences in the properties of alkalis and water-insoluble bases, but a common property is the reaction of interaction with acids. The chemical properties of the bases are presented in Table 6.

Table 6 – Chemical properties reasons

Alkalis	Insoluble bases
All bases react with acids ( neutralization reaction)
2NaOH + H 2 SO 4 = Na 2 SO 4 + 2H 2 O	Cr(OH) 2 + 2HC1 = CrC1 2 + 2H 2 O
The bases react With acid oxides with the formation of salt and water: 6KON + P 2 O 5 = 2K 3 PO 4 + 3H 2 O
Alkalis react with salt solutions, if one of the reaction products precipitates(i.e. if an insoluble compound is formed): CuSO 4 + 2KOH = Cu(OH) 2  + K 2 SO 4 Na 2 SO 4 + Ba(OH) 2 = 2NaOH + BaSO 4 	Bases that are insoluble in water and amphoteric hydroxides decompose when heated to the corresponding oxide and water: Mn(OH) 2  MnO + H 2 O Cu(OH) 2  CuO + H 2 O
Alkalis can be detected with an indicator. In an alkaline environment: litmus - blue, phenolphthalein - crimson, methyl orange - yellow

3.1.5 Essential reasons.

NaOH– caustic soda, caustic soda. Low-melting (t pl = 320 °C) white hygroscopic crystals, highly soluble in water. The solution is soapy to the touch and is a dangerously caustic liquid. NaOH is one of the most important products of the chemical industry. It is required in large quantities for the purification of petroleum products, and is widely used in soap, paper, textile and other industries, as well as for the production of artificial fiber.

CON- caustic potassium. White hygroscopic crystals, highly soluble in water. The solution is soapy to the touch and is a dangerously caustic liquid. The properties of KOH are similar to those of NaOH, but potassium hydroxide is used much less frequently due to its higher cost.

Ca(OH) 2 - slaked lime. White crystals, slightly soluble in water. The solution is called “lime water”, the suspension is called “lime milk”. Lime water used to recognize carbon dioxide, it becomes cloudy when CO 2 is passed through. Slaked lime is widely used in construction as a base for the production of binders.

General properties bases are due to the presence of the OH - ion in their solutions, creating in solution alkaline environment(phenolphthalein turns crimson, methyl orange turns yellow, litmus turns blue).

1. Chemical properties of alkalis:

1) interaction with acid oxides:

2KOH+CO 2 ®K 2 CO 3 +H 2 O;

2) reaction with acids (neutralization reaction):

2NaOH+ H 2 SO 4 ®Na 2 SO 4 +2H 2 O;

3) interaction with soluble salts (only if, when an alkali acts on a soluble salt, a precipitate forms or a gas is released):

2NaOH+ CuSO 4 ®Cu(OH) 2 ¯+Na 2 SO 4,

Ba(OH) 2 +Na 2 SO 4 ®BaSO 4 ¯+2NaOH, KOH(conc.)+NH 4 Cl(crystalline) ®NH 3 +KCl+H 2 O.

2. Chemical properties insoluble bases:

1) interaction of bases with acids:

Fe(OH) 2 +H 2 SO 4 ®FeSO 4 +2H 2 O;

2) decomposition when heated. Insoluble bases decompose when heated into basic oxide and water:

Cu(OH) 2 ®CuO+H 2 O

End of work -

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Atomic molecular studies in chemistry. Atom. Molecule. Chemical element. Mol. Simple complex substances. Examples

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Getting grounds
1. Preparation of alkalis: 1) interaction of alkali or alkaline earth metals or their oxides with water: Ca+2H2O®Ca(OH)2+H

Nomenclature of acids
The names of acids are derived from the element from which the acid is formed. Moreover, in the title oxygen-free acids usually there is a -hydrogen ending: HCl - hydrochloric, HBr - hydrogen bromide

Chemical properties of acids
The general properties of acids in aqueous solutions are determined by the presence of H+ ions formed during the dissociation of acid molecules, thus, acids are proton donors: HxAn«xH+

Obtaining acids
1) interaction of acid oxides with water: SO3+H2O®H2SO4, P2O5+3H2O®2H3PO4;

Chemical properties of acid salts
1) acid salts contain hydrogen atoms that can take part in the neutralization reaction, so they can react with alkalis, turning into medium or other acid salts - with a smaller number

Obtaining acid salts
The acid salt can be obtained: 1) by the reaction of incomplete neutralization of a polybasic acid with a base: 2H2SO4+Cu(OH)2®Cu(HSO4)2+2H

Basic salts.
Basic (hydroxo salts) are salts that are formed as a result of incomplete replacement of the hydroxide ions of the base with acid anions. Single acid bases, e.g. NaOH, KOH,

Chemical properties of basic salts
1) basic salts contain hydroxo groups that can take part in the neutralization reaction, so they can react with acids, turning into intermediate salts or basic salts with less

Preparation of basic salts
The main salt can be obtained: 1) by the reaction of incomplete neutralization of the base with an acid: 2Cu(OH)2+H2SO4®(CuOH)2SO4+2H2

Medium salts.
Medium salts are the products of complete replacement of H+ ions of an acid with metal ions; they can also be considered as products of complete replacement of the OH ions of the base anion

Nomenclature of medium salts
In Russian nomenclature (used in technological practice) there is the following order of naming medium salts: to the root of the name oxygenated acid add a word

Chemical properties of medium salts
1) Almost all salts are ionic compounds, therefore, in a melt and in an aqueous solution, they dissociate into ions (when current is passed through solutions or molten salts, the process of electrolysis occurs).

Preparation of medium salts
Most of methods for obtaining salts is based on the interaction of substances of opposite nature - metals with non-metals, acidic oxides with basic ones, bases with acids (see Table 2).

The structure of the atom.
An atom is an electrically neutral particle consisting of a positively charged nucleus and negatively charged electrons. Serial number of the element in periodic table elements equal to charge kernels

Composition of atomic nuclei
The nucleus consists of protons and neutrons. The number of protons is serial number element. The number of neutrons in the nucleus is equal to the difference between the mass number of the isotope and

Electron
Electrons rotate around the nucleus in certain stationary orbits. Moving along its orbit, an electron does not emit or absorb electromagnetic energy. Emission or absorption of energy occurs

Rule for filling electronic levels and sublevels of elements
The number of electrons that can be at one energy level is determined by the formula 2n2, where n is the number of the level. Maximum filling of the first four energy levels: for the first

Ionization energy, electron affinity, electronegativity.
Ionization energy of an atom. The energy required to remove an electron from an unexcited atom is called the first ionization energy (potential) I: E + I = E+ + e- Ionization energy

Covalent bond
In most cases, when a bond is formed, the electrons of the bonded atoms are shared. This type of chemical bond is called a covalent bond (the prefix "co-" in Latin

Sigma and pi connections.
Sigma (σ)-, pi (π)-bonds - an approximate description of the types of covalent bonds in molecules of various compounds, the σ-bond is characterized by the fact that the density of the electron cloud is maximum

Formation of a covalent bond by a donor-acceptor mechanism.
In addition to the homogeneous mechanism of covalent bond formation outlined in the previous section, there is a heterogeneous mechanism - the interaction of oppositely charged ions - the H+ proton and

Chemical bonding and molecular geometry. BI3, PI3
Figure 3.1 Addition of dipole elements in NH3 and NF3 molecules

Polar and non-polar bond
Covalent bond is formed as a result of the socialization of electrons (with the formation of common electron pairs), which occurs during the overlap of electron clouds. In education

Ionic bond
Ionic bond is a chemical bond that occurs through the electrostatic interaction of oppositely charged ions. Thus, the process of education and

Oxidation state
Valency 1. Valency is the ability of atoms chemical elements form certain number chemical bonds. 2. Valency values ​​vary from I to VII (rarely VIII). Valens

Hydrogen bond
In addition to various heteropolar and homeopolar bonds, there is one more special kind communications, which in the last two decades has attracted everyone more attention chemists. This is the so-called hydrogen

Crystal lattices
So, crystal structure characterized by the correct (regular) arrangement of particles in a strictly certain places in crystal. When you mentally connect these points with lines, you get spaces.

Solutions
If you place crystals in a vessel with water table salt, sugar or potassium permanganate (potassium permanganate), then we can observe how the amount of solid substance gradually decreases. At the same time, water

Electrolytic dissociation
Solutions of all substances can be divided into two groups: electrolytes - conduct electricity, non-electrolytes are not conductors. This division is conditional, because everything

Dissociation mechanism.
Water molecules are dipole, i.e. one end of the molecule is negatively charged, the other is positively charged. The molecule has a negative pole approaching the sodium ion, and a positive pole approaching the chlorine ion; surround io

Ionic product of water
pH value(pH) is a value characterizing the activity or concentration of hydrogen ions in solutions. The hydrogen indicator is designated pH. The hydrogen index is numerically

Chemical reaction
A chemical reaction is the transformation of one substance into another. However, such a definition needs one significant addition. IN nuclear reactor or in the accelerator, too, some substances are converted

Methods for arranging coefficients in OVR
Method electronic balance 1). We write the equation chemical reaction KI + KMnO4 → I2 + K2MnO4 2). Finding atoms

Hydrolysis
Hydrolysis is a process of exchange interaction between salt ions and water, leading to the formation of slightly dissociated substances and accompanied by a change in the reaction (pH) of the medium. The essence

Rate of chemical reactions
The reaction rate is determined by a change in the molar concentration of one of the reactants: V = ± ((C2 – C1) / (t2 - t

Factors affecting the rate of chemical reactions
1. The nature of the reacting substances. Big role plays a role in the nature of chemical bonds and the structure of the reagent molecules. Reactions proceed in the direction of destruction less strong ties and the formation of substances with

Activation energy
The collision of chemical particles leads to chemical interaction only if the colliding particles have energy exceeding some specific value. Let's consider each other

Catalysis catalyst
Many reactions can be accelerated or slowed down by the introduction of certain substances. The added substances do not participate in the reaction and are not consumed during its course, but have a significant effect on

Chemical equilibrium
Chemical reactions that proceed at comparable rates in both directions are called reversible. In such reactions, equilibrium mixtures of reagents and products are formed, the composition of which

Le Chatelier's principle
Le Chatelier's principle says that in order to shift the equilibrium to the right, you must firstly increase the pressure. Indeed, as the pressure increases, the system will “resist” the increase in con

Factors influencing the rate of a chemical reaction
Factors influencing the rate of a chemical reaction Increase the speed Reduce the speed Presence of chemically active reagents

Hess's law
Using table values

Thermal effect
During the reaction, bonds in the starting substances are broken and new bonds are formed in the reaction products. Since the formation of a bond occurs with the release, and its breaking occurs with the absorption of energy, then x

Bases (hydroxides)– complex substances whose molecules contain one or more hydroxy OH groups. Most often, bases consist of a metal atom and an OH group. For example, NaOH is sodium hydroxide, Ca(OH) 2 is calcium hydroxide, etc.

There is a base - ammonium hydroxide, in which the hydroxy group is attached not to the metal, but to the NH 4 + ion (ammonium cation). Ammonium hydroxide is formed when ammonia is dissolved in water (the reaction of adding water to ammonia):

NH 3 + H 2 O = NH 4 OH (ammonium hydroxide).

The valency of the hydroxy group is 1. The number of hydroxyl groups in the base molecule depends on the valence of the metal and is equal to it. For example, NaOH, LiOH, Al (OH) 3, Ca(OH) 2, Fe(OH) 3, etc.

All reasons - solids who have different colors. Some bases are highly soluble in water (NaOH, KOH, etc.). However, most of them are not soluble in water.

Bases soluble in water are called alkalis. Alkali solutions are “soapy”, slippery to the touch and quite caustic. Alkalies include hydroxides of alkali and alkaline earth metals (KOH, LiOH, RbOH, NaOH, CsOH, Ca(OH) 2, Sr(OH) 2, Ba(OH) 2, etc.). The rest are insoluble.

Insoluble bases- these are amphoteric hydroxides, which act as bases when interacting with acids, and behave like acids with alkali.

Different bases have different abilities to remove hydroxy groups, so they are divided into strong and weak bases.

Strong bases in aqueous solutions easily give up their hydroxy groups, but weak bases do not.

Chemical properties of bases

The chemical properties of bases are characterized by their relationship to acids, acid anhydrides and salts.

1. Act on indicators. Indicators change color depending on interaction with different chemicals. IN neutral solutions- they have one color, in acid solutions - another. When interacting with bases, they change their color: the methyl orange indicator turns yellow, litmus indicator – in Blue colour, and phenolphthalein becomes fuchsia.

2. Interact with acid oxides with formation of salt and water:

2NaOH + SiO 2 → Na 2 SiO 3 + H 2 O.

3. React with acids, forming salt and water. The reaction of a base with an acid is called a neutralization reaction, since after its completion the medium becomes neutral:

2KOH + H 2 SO 4 → K 2 SO 4 + 2H 2 O.

4. Reacts with salts forming a new salt and base:

2NaOH + CuSO 4 → Cu(OH) 2 + Na 2 SO 4.

5. When heated, they can decompose into water and the main oxide:

Cu(OH) 2 = CuO + H 2 O.

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Mono-acid (NaOH, KOH, NH 4 OH, etc.);

Diacid (Ca(OH)2, Cu(OH)2, Fe(OH)2;

Three-acid (Ni(OH) 3, Co(OH) 3, Mn(OH) 3.

Classification according to water solubility and degree of ionization:

Water-soluble strong bases

For example:

alkalis - hydroxides of alkali and alkaline earth metals LiOH - lithium hydroxide, NaOH - sodium hydroxide ( sodium hydroxide), KOH - potassium hydroxide (caustic potash), Ba(OH) 2 - barium hydroxide;

Strong bases that are insoluble in water

For example:

Cu(OH) 2 - copper (II) hydroxide, Fe(OH) 2 - iron (II) hydroxide, Ni(OH) 3 - nickel (III) hydroxide.

Chemical properties

1. Action on indicators

Litmus - blue;

Methyl orange - yellow,

Phenolphthalein - raspberry.

2. Interaction with acid oxides

2KOH + CO 2 = K 2 CO 3 + H 2 O

KOH + CO 2 = KHCO 3

3. Interaction with acids (neutralization reaction)

NaOH + HNO 3 = NaNO 3 + H 2 O; Cu(OH) 2 + 2HCl = CuCl 2 + 2H 2 O

4. Exchange reaction with salts

Ba(OH) 2 + K 2 SO 4 = 2KOH + BaSO 4

3KOH + Fe(NO 3) 3 = Fe(OH) 3 + 3KNO 3

5. Thermal decomposition

Cu(OH) 2 t = CuO + H 2 O; 2 CuOH = Cu 2 O + H 2 O

2Co(OH) 3 = Co 2 O 3 + ZH 2 O; 2AgOH = Ag 2 O + H 2 O

6. Hydroxides in which d-metals have low c. o., capable of being oxidized by atmospheric oxygen,

For example:

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

2Mn(OH) 2 + O 2 + 2H 2 O = 2Mn(OH) 4

7. Alkali solutions interact with amphoteric hydroxides:

2KOH + Zn(OH) 2 = K 2

2KON + Al 2 O 3 + ZN 2 O = 2K

8. Alkali solutions interact with metals that form amphoteric oxides and hydroxides (Zn, AI, etc.),

For example:

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

2AI + 2KOH + 6H 2 O= 2KAl(OH) 4 ] + 3H 2

9. In alkali solutions, some non-metals are disproportionate,

For example:

Cl 2 + 2NaOH = NaCl + NaCIO + H 2 O

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

4P+ 3KOH + 3H 2 O = PH 3 + 3KH 2 PO 2

10. Soluble bases widely used in reactions alkaline hydrolysis various organic compounds(halogenated hydrocarbons, esters, fats, etc.),

For example:

C 2 H 5 CI + NaOH = C 2 H 5 OH + NaCl

Methods for obtaining alkalis and insoluble bases

1. Reactions active metals(alkali and alkaline earth metals) with water:

2Na + 2H2O = 2NaOH + H2

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

2. Interaction of active metal oxides with water:

BaO + H 2 O = Ba(OH) 2

3. Electrolysis of aqueous salt solutions:

2NaCl + 2H 2 O = 2NaOH + H 2 + Cl 2

CaCI 2 + 2H 2 O = Ca(OH) 2 + H 2 + Cl 2

4. Precipitation from solutions of the corresponding salts with alkalis:

CuSO 4 + 2NaOH = Cu(OH) 2 + Na 2 SO 4

FeCI 3 + 3KOH = Fe(OH) 3 + 3KCI