Obtaining the physical and chemical properties of bases. Acids and bases

The division of bases into groups according to various characteristics is presented in Table 11.

Table 11
Classification of bases

All bases, except a solution of ammonia in water, are solid substances of different colors. For example, calcium hydroxide Ca(OH) 2 white, copper (II) hydroxide Cu(OH) 2 blue color, nickel (II) hydroxide Ni(OH) 2 green, iron (III) hydroxide Fe(OH) 3 red-brown, etc.

An aqueous solution of ammonia NH 3 H 2 O, unlike other bases, does not contain metal cations, but a complex single-charge ammonium cation NH - 4 and exists only in solution (you know this solution as ammonia). It easily decomposes into ammonia and water:

However, no matter how different the bases are, they all consist of metal ions and hydroxo groups, the number of which is equal to the oxidation state of the metal.

All bases, and primarily alkalis (strong electrolytes), form upon dissociation hydroxide ions OH -, which determine a number of general properties: soapiness to the touch, change in color of indicators (litmus, methyl orange and phenolphthalein), interaction with other substances.

Typical base reactions

The first reaction (universal) was considered in § 38.

Laboratory experiment No. 23
Interaction of alkalis with acids

H + + OH - = H 2 O.

Carry out the reactions for which you have created equations. Remember what substances (except acid and alkali) are needed to observe these chemical reactions.

The second reaction occurs between alkalis and non-metal oxides, which correspond to acids, for example,

Compliant

etc.

When oxides interact with bases, salts of the corresponding acids and water are formed:

Rice. 141.
Interaction of alkali with non-metal oxide

Laboratory experiment No. 24
Interaction of alkalis with non-metal oxides

Repeat the experiment you did before. Pour 2-3 ml of a clear solution of lime water into a test tube.

Place a juice straw in it, which acts as a gas outlet tube. Gently pass exhaled air through the solution. What are you observing?

Write down the molecular and ionic equations for the reaction.

Rice. 142.
Interaction of alkalis with salts:
a - with the formation of sediment; b - with gas formation

The third reaction is a typical ion exchange reaction and only occurs if it results in a precipitate or gas being released, for example:

Laboratory experiment No. 25
Interaction of alkalis with salts

Heat the contents of the 1st test tube and identify one of the reaction products by smell.

Formulate a conclusion about the possibility of interaction of alkalis with salts.

Insoluble bases decompose when heated into metal oxide and water, which is not typical for alkalis, for example:

Fe(OH) 2 = FeO + H 2 O.

Laboratory experiment No. 26
Preparation and properties of insoluble bases

Pour 1 ml of copper (II) sulfate or chloride solution into two test tubes. Add 3-4 drops of sodium hydroxide solution to each test tube. Describe the copper(II) hydroxide formed.

Note. Leave the test tubes with the resulting copper (II) hydroxide for the next experiments.

Write down the molecular and ionic equations for the reaction. Indicate the type of reaction based on the “number and composition of starting substances and reaction products.”

Add 1-2 ml of hydrochloric acid to one of the test tubes with copper (II) hydroxide obtained in the previous experiment. What are you observing?

Using a pipette, place 1-2 drops of the resulting solution on a glass or porcelain plate and, using crucible tongs, carefully evaporate it. Examine the crystals that form. Note their color.

Write down the molecular and ionic equations for the reaction. Indicate the type of reaction based on “the number and composition of starting materials and reaction products,” “participation of a catalyst,” and “reversibility of a chemical reaction.”

Heat one of the test tubes with copper hydroxide obtained earlier or given by the teacher (Fig. 143). What are you observing?

Rice. 143.
Decomposition of copper(II) hydroxide when heated

Draw up an equation for the reaction carried out, indicate the condition for its occurrence and the type of reaction based on the characteristics “number and composition of starting substances and reaction products”, “release or absorption of heat” and “reversibility of a chemical reaction”.

Key words and phrases

Classification of bases.
Typical properties of bases: their interaction with acids, non-metal oxides, salts.
A typical property of insoluble bases is decomposition when heated.
Conditions for typical base reactions.

Working with a computer

Refer to the electronic application. Study the lesson material and complete the assigned tasks.
Find email addresses on the Internet that can serve as additional sources that reveal the content of keywords and phrases in the paragraph. Offer your help to the teacher in preparing a new lesson - send a message by keywords and phrases in the next paragraph.

Questions and tasks

After reading the article, you will be able to separate substances into salts, acids and bases. The article describes what the pH of a solution is, what general properties have acids and bases.

Like metals and nonmetals, acids and bases are the division of substances based on similar properties. The first theory of acids and bases belonged to the Swedish scientist Arrhenius. An Arrhenius acid is a class of substances that, when reacting with water, dissociate (decay), forming the hydrogen cation H +. Arrhenius bases in aqueous solution form OH - anions. The next theory was proposed in 1923 by scientists Bronsted and Lowry. The Brønsted-Lowry theory defines acids as substances capable of donating a proton in a reaction (a hydrogen cation is called a proton in reactions). Bases, accordingly, are substances that can accept a proton in a reaction. Current on at the moment theory - Lewis theory. Lewis theory defines acids as molecules or ions capable of accepting electron pairs, thereby forming Lewis adducts (an adduct is a compound formed by combining two reactants without forming by-products).

IN inorganic chemistry, as a rule, by acid they mean a Brønsted-Lowry acid, that is, substances capable of donating a proton. If they mean the definition of a Lewis acid, then in the text such an acid is called a Lewis acid. These rules apply to acids and bases.

Dissociation

Dissociation is the process of decomposition of a substance into ions in solutions or melts. For example, the dissociation of hydrochloric acid is the decomposition of HCl into H + and Cl -.

Properties of acids and bases

Bases tend to feel soapy to the touch, while acids generally taste sour.

When a base reacts with many cations, a precipitate is formed. When an acid reacts with anions, a gas is usually released.

Commonly used acids:
H 2 O, H 3 O +, CH 3 CO 2 H, H 2 SO 4, HSO 4 −, HCl, CH 3 OH, NH 3

Commonly used bases:
OH − , H 2 O, CH 3 CO 2 − , HSO 4 − , SO 4 2 − , Cl −

Strong and weak acids and bases

Strong acids

Such acids that completely dissociate in water, producing hydrogen cations H + and anions. An example of a strong acid is hydrochloric acid HCl:

HCl (solution) + H 2 O (l) → H 3 O + (solution) + Cl - (solution)

Examples of strong acids: HCl, HBr, HF, HNO 3, H 2 SO 4, HClO 4

List of strong acids

HCl - hydrochloric acid
HBr - hydrogen bromide
HI - hydrogen iodide
HNO3- nitric acid
HClO 4 - perchloric acid
H 2 SO 4 - sulfuric acid

Weak acids

Only partially dissolved in water, for example, HF:

HF (solution) + H2O (l) → H3O + (solution) + F - (solution) - in such a reaction more than 90% of the acid does not dissociate:
= < 0,01M для вещества 0,1М

Strong and weak acids can be distinguished by measuring the conductivity of solutions: conductivity depends on the number of ions, the stronger the acid, the more dissociated it is, therefore, the stronger the acid, the higher the conductivity.

List of weak acids

HF hydrogen fluoride
H 3 PO 4 phosphoric
H 2 SO 3 sulfurous
H 2 S hydrogen sulfide
H 2 CO 3 coal
H 2 SiO 3 silicon

Strong grounds

Strong bases completely dissociate in water:

NaOH (solution) + H 2 O ↔ NH 4

Strong bases include metal hydroxides of the first (alkalines, alkali metals) and second (alkalinotherrenes, alkaline earth metals) groups.

List of strong bases

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)

Weak foundations

In a reversible reaction in the presence of water, it forms OH - ions:

NH 3 (solution) + H 2 O ↔ NH + 4 (solution) + OH - (solution)

Most weak bases are anions:

F - (solution) + H 2 O ↔ HF (solution) + OH - (solution)

List of weak bases

Mg(OH) 2 magnesium hydroxide
Fe(OH) 2 iron(II) hydroxide
Zn(OH) 2 zinc hydroxide
NH 4 OH ammonium hydroxide
Fe(OH) 3 iron(III) hydroxide

Reactions of acids and bases

Strong acid and strong base

This reaction is called neutralization: when the amount of reagents is sufficient to completely dissociate the acid and base, the resulting solution will be neutral.

Example:
H 3 O + + OH - ↔ 2H 2 O

Weak base and weak acid

General view reactions:
Weak base (solution) + H 2 O ↔ Weak acid (solution) + OH - (solution)

Strong base and weak acid

The base dissociates completely, the acid dissociates partially, the resulting solution has weak properties of a base:

HX (solution) + OH - (solution) ↔ H 2 O + X - (solution)

Strong acid and weak base

The acid dissociates completely, the base dissociates not completely:

Dissociation of water

Dissociation is the breakdown of a substance into its component molecules. The properties of an acid or base depend on the equilibrium that is present in water:

H 2 O + H 2 O ↔ H 3 O + (solution) + OH - (solution)
K c = / 2
The equilibrium constant of water at t=25°: K c = 1.83⋅10 -6, the following equality also holds: = 10 -14, which is called the dissociation constant of water. For clean water= = 10 -7, from where -lg = 7.0.

This value (-lg) is called pH - hydrogen potential. If pH< 7, то вещество имеет кислотные свойства, если pH >7, then the substance has basic properties.

Methods for determining pH

Instrumental method

A special device, a pH meter, is a device that transforms the concentration of protons in a solution into an electrical signal.

Indicators

A substance that changes color in a certain pH range depending on the acidity of the solution; using several indicators you can achieve a fairly accurate result.

Salt

A salt is an ionic compound formed by a cation other than H+ and an anion other than O2-. In a weak aqueous solution, the salts completely dissociate.

To determine the acid-base properties of a salt solution, it is necessary to determine which ions are present in the solution and consider their properties: neutral ions formed from strong acids and bases do not affect pH: they do not release either H + or OH - ions in water. For example, Cl -, NO - 3, SO 2- 4, Li +, Na +, K +.

Anions formed from weak acids exhibit alkaline properties (F -, CH 3 COO -, CO 2- 3); cations with alkaline properties do not exist.

All cations except metals of the first and second groups have acidic properties.

Buffer solution

Solutions that maintain pH when added small quantity strong acid or strong base, mainly composed of:

A mixture of a weak acid, its corresponding salt and a weak base
Weak base, corresponding salt and strong acid

To prepare a buffer solution of a certain acidity, it is necessary to mix a weak acid or base with the appropriate salt, taking into account:

pH range in which the buffer solution will be effective
Solution capacity - the amount of strong acid or strong base that can be added without affecting the pH of the solution
There should be no unwanted reactions that could change the composition of the solution

Test:

DEFINITION

Reasons are called electrolytes, upon dissociation of which only OH - ions are formed from negative ions:

Fe(OH) 2 ↔ Fe 2+ + 2OH - ;

NH 3 + H 2 O ↔ NH 4 OH ↔ NH 4 + + OH - .

All inorganic bases are classified into water-soluble (alkalis) - NaOH, KOH and water-insoluble (Ba(OH) 2, Ca(OH) 2). Depending on the exhibited chemical properties, amphoteric hydroxides are distinguished among the bases.

Chemical properties of bases

When indicators act on solutions of inorganic bases, their color changes, so when a base gets into a solution, litmus becomes blue, methyl orange becomes yellow, and phenolphthalein becomes crimson.

Inorganic bases are able to react with acids to form salt and water, and water-insoluble bases react only with water-soluble acids:

Cu(OH) 2 ↓ + H 2 SO 4 = CuSO 4 +2H 2 O;

NaOH + HCl = NaCl + H 2 O.

Bases that are insoluble in water are thermally unstable, i.e. when heated, they undergo decomposition to form oxides:

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

Mg(OH) 2 = MgO + H 2 O.

Alkalis (water-soluble bases) react with acidic oxides to form salts:

NaOH + CO 2 = NaHCO 3.

Alkalis are also capable of entering into interaction reactions (ORR) with some non-metals:

2NaOH + Si + H 2 O → Na 2 SiO 3 +H 2.

Some bases enter into exchange reactions with salts:

Ba(OH) 2 + Na 2 SO 4 = 2NaOH + BaSO 4 ↓.

Amphoteric hydroxides (bases) also exhibit the properties of weak acids and react with alkalis:

Al(OH) 3 + NaOH = Na.

Amphoteric bases include aluminum and zinc hydroxides. chromium (III), etc.

Physical properties of bases

Most bases are solids that vary in solubility in water. Alkalis are water-soluble bases that are most often white solids. Water-insoluble bases can have different colors, for example, iron (III) hydroxide is a brown solid, aluminum hydroxide is a white solid, and copper (II) hydroxide is a blue solid.

Getting grounds

Reasons get in different ways, for example, according to the reaction:

- exchange

CuSO 4 + 2KOH → Cu(OH) 2 ↓ + K 2 SO 4 ;

K 2 CO 3 + Ba(OH) 2 → 2KOH + BaCO 3 ↓;

— interactions of active metals or their oxides with water

2Li + 2H 2 O→ 2LiOH +H 2;

BaO + H 2 O → Ba(OH) 2 ↓;

— electrolysis of aqueous salt solutions

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

Examples of problem solving

EXAMPLE 1

Exercise

Calculate the practical mass of aluminum oxide (the yield of the target product is 92%) from the decomposition reaction of aluminum hydroxide weighing 23.4 g.

Solution

Let's write the reaction equation:

2Al(OH) 3 = Al 2 O 3 + 3H 2 O.

Molar mass of aluminum hydroxide calculated using table chemical elements DI. Mendeleev – 78 g/mol. Let's find the amount of aluminum hydroxide:

v(Al(OH) 3) = m(Al(OH) 3)/M(Al(OH) 3);

v(Al(OH) 3) = 23.4/78 = 0.3 mol.

According to the reaction equation v(Al(OH) 3): v(Al 2 O 3) = 2:1, therefore, the amount of aluminum oxide substance will be:

v(Al 2 O 3) = 0.5 × v(Al(OH) 3);

v(Al 2 O 3) = 0.5 × 0.3 = 0.15 mol.

Molar mass of aluminum oxide, calculated using the table of chemical elements by D.I. Mendeleev – 102 g/mol. Let's find the theoretical mass of aluminum oxide:

m(Al 2 O 3) th = 0.15×102 = 15.3 g.

Then, the practical mass of aluminum oxide is:

m(Al 2 O 3) pr = m(Al 2 O 3) th × 92/100;

m(Al 2 O 3) pr = 15.3 × 0.92 = 14 g.

Answer

Weight of aluminum oxide - 14 g.

EXAMPLE 2

Exercise

Carry out a series of transformations:

Fe→ FeCl 2 → Fe(OH) 2 →Fe(OH) 3 →Fe(NO 3) 3

LESSON OBJECTIVES:

Educational: study the bases, their classification, methods of preparation and properties.
Developmental: help consolidate knowledge about classes of inorganic compounds, develop and deepen the understanding of hydroxides.
Educational: instill an interest in the subject of chemistry, follow safety rules when handling. with bases (alkalis).

Equipment: multimedia, computer, tasks, PSHE, solubility table, alkalis, copper chloride, indicators.

Lesson progress

Organizational moment. Checking homework.

I. Lesson motivation.

Teacher: What can replace shampoo and soap?

Lye is a consistency of ash infused with water. The lye in the ecovillage is used for bathing and washing. Unlike various detergents sold in stores, this is completely natural substance! Washing hair with ash is one of the ancient remedies used by our great-grandmothers. Birch ash - has alkaline properties due to its potash content.

II. Announcing the topic of the lesson. Goal setting.

Teacher. Lesson topic: “Foundations, their classification and properties.”

III. Updating knowledge.

Hydroxides are compounds consisting of metal atoms and hydroxide ions.

From the point of view of TED, bases are electrolytes that dissociate in aqueous solutions into metal cations and hydroxide anions.

NaOH<->Na + + OH -

Ba(OH)2<->Ba +2 + 2OH -

IV. Learning new material. Awareness and comprehension.

Teacher. Let's study the classification of bases:

a) By solubility in water: soluble and insoluble

b) By acidity: one-acid and two-acid

c) According to the degree of electrolytic dissociation: strong and weak

If you add alkali to salt,
Look at the test tube -
A blue precipitate will form -
Base - copper hydroxide II.

Fe(OH) 3 red-brown,
Cr(OH) 3 - gray-green,
Co(OH) 2 - dark purple,
Ni(OH) 2 - light green.

Teacher. Look at the physical properties of laundry soap. Alkalis are also soft and soapy to the touch and change the color of indicators. Let's conduct an experiment:

Phenolphthalein (colorless) + alkali -> crimson color

Litmus (violet) + alkali -> blue color

NaOH and KOH are strong alkalis, which must be handled in accordance with safety regulations.

3. Methods for obtaining bases

A) Active metal and water

B) basic oxide and water

(Write equations of chemical reactions independently)

4. Consider chemical properties reasons

A) with acids

B) with acid oxides

B) with amphoteric oxides

D) with soluble salts

D) change the color of the indicators. (Dem experience)

A). Base + acid > salt + water

(exchange reaction)

2NaOH + H 2 SO 4 -> Na 2 SO4 + 2H 2 O

OH - + H + -> H 2 O

Cu(OH) 2 + 2HCl -> CuCl 2 + 2H 2 O

Cu(OH) 2 + 2H + -> Cu +2 + 2H 2 O

B) Base + acid oxide -> salt + water (exchange reaction)

R 2 O 5 + 6KON -> 2K 3 RO 4 + 3H 2 O

P 2 O 5 + 6OH - -> 2PO 4 3- + 3H 2 O

2NaOH + N 2 O 5 -> 2NaNO 3 + H 2 O

2OH - + N 2 O 5 -> 2NO 3 - + H 2 O

Teacher. The interaction of alkalis with salts is accompanied by the formation of a new salt and a new base and obeys Berthollet's law. Berthollet's law is the basic law of the direction of reversible chemicals. interactions, which can be formulated as follows: every chemical process proceeds towards the maximum formation of those products that during the reaction leave the sphere of interaction.

IN). Alkali + salt > new base + new salt (exchange reaction)

G). Insoluble base -> metal oxide + water (at t°C)

(decomposition reaction)

Fe(OH) 2 -> FeO + H 2 O

Cu(OH) 2 -> CuO + H 2 O

D) Change the color of the indicator

5. SPECIAL PROPERTIES OF BASES

1. Qualitative reaction to Ca(OH) 2 - turbidity of lime water:

Qualitative reactions to the Ba +2 ion:

V. Consolidation of the studied material

Teacher. To consolidate the material, we will complete tasks.

1. Using the table of solubility of salts, acids and bases in water, find soluble, sparingly soluble and slightly soluble bases.

2. Make up molecular reaction equations:

3. Write reaction equations characterizing the chemical properties of potassium hydroxide.

Teacher. Complete the test tasks:

Option 1:
1. Formulas of only bases are given in a row
a) Na 2 CO 3, NaOH, NaCl
b) KNO 3, HNO 3, KOH
c) KOH, Mg(OH) 2, Cu(OH) 2
d) HCl, BaCl 2, Ba(OH) 2
2. Formulas of only alkalis are given in a row
a) Fe(OH) 3, NaOH, Ca(OH) 2
b) KOH, LiOH, NaOH
c) KOH, Mg(OH) 2, Cu(OH) 2
d) Al(OH) 3, Fe(OH) 2, Ba(OH) 2
3. Of the above compounds, the base insoluble in water is
a) NaOH
b) Ba(OH) 2
c) Fe(OH) 2
d) KOH
4. Of the indicated compounds, alkali is
a) Fe(OH) 2
b) LiOH
c) Mg(OH) 2
d) Cu(OH) 2

2-Option:
1. A metal that reacts with water to form an alkali is
a) iron
b) copper
c) potassium
d) aluminum
2. An oxide that, when interacting with water, forms an alkali is
a) aluminum oxide
b) lithium oxide
c) lead(II) oxide
d) manganese(II) oxide
3. When the basic oxide reacts with water, a base is formed
a) Al(OH) 3
b) Ba(OH) 2
c) Cu(OH) 2
d) Fe(OH) 3
4. From the listed equations chemical reactions choose the exchange reaction equation.
a) 2H 2 O = 2H 2 + O 2
b) HgCl 2 + Fe = FeCl 2 + Hg
c) ZnCl 2 + 2KOH = Zn(OH) 2 + 2KCl
d) CaO + CO 2 = CaCO 3
Answers: Option 1: 1-B, 2-B, 3-B, 4-B.; Option 2: 1-B, 2-B, 3-B, 4-B.

VI. Summing up the lesson.

Teacher. Which general conclusion can this be done by studying the composition and properties of bases?

Students conclude that the properties of bases depend on their structure and write it down in their notebook.

Grading.

Homework.p.217-218 No. 1-5

One of the difficult classes inorganic substances- grounds. These are compounds that include metal atoms and a hydroxyl group, which can be split off when interacting with other substances.

Structure

Bases may contain one or more hydroxo groups. General formula bases - Me(OH) x. There is always one metal atom, and the number of hydroxyl groups depends on the valence of the metal. In this case, the valence of the OH group is always I. For example, in the NaOH compound the valency of sodium is I, therefore, there is one hydroxyl group. At the base Mg(OH) 2 the valence of magnesium is II, Al(OH) 3 the valence of aluminum is III.

The number of hydroxyl groups can vary in compounds with metals of variable valency. For example, Fe(OH) 2 and Fe(OH) 3. In such cases, the valence is indicated in parentheses after the name - iron (II) hydroxide, iron (III) hydroxide.

Physical properties

The characteristics and activity of the base depend on the metal. Most bases are odorless, white solids. However, some metals give the substance a characteristic color. For example, CuOH has yellow, Ni(OH) 2 - light green, Fe(OH) 3 - red-brown.

Rice. 1. Alkalis in solid state.

Species

The bases are classified according to two criteria:

by number of OH groups- single-acid and multi-acid;
by solubility in water- alkalis (soluble) and insoluble.

Alkalis are formed alkali metals- lithium (Li), sodium (Na), potassium (K), rubidium (Rb) and cesium (Cs). In addition, active metals that form alkalis include the alkaline earth metals - calcium (Ca), strontium (Sr) and barium (Ba).

These elements form the following bases:

LiOH;
NaOH;
RbOH;
CsOH;
Ca(OH)2;
Sr(OH)2;
Ba(OH)2.

All other bases, for example, Mg(OH) 2, Cu(OH) 2, Al(OH) 3, are classified as insoluble.

In another way, alkalis are called strong bases, and insoluble alkalis are called weak bases. During electrolytic dissociation, alkalis quickly give up a hydroxyl group and react more quickly with other substances. Insoluble or weak bases are less active because do not donate a hydroxyl group.

Rice. 2. Classification of bases.

Amphoteric hydroxides occupy a special place in the systematization of inorganic substances. They interact with both acids and bases, i.e. Depending on the conditions, they behave like an alkali or an acid. These include Zn(OH) 2 , Al(OH) 3 , Pb(OH) 2 , Cr(OH) 3 , Be(OH) 2 and other bases.

Receipt

Reasons get in various ways. The simplest is the interaction of metal with water:

Ba + 2H 2 O → Ba(OH) 2 + H 2.

Alkalis are obtained by reacting the oxide with water:

Na 2 O + H 2 O → 2NaOH.

Insoluble bases are obtained as a result of the interaction of alkalis with salts:

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

Chemical properties

The main chemical properties of the bases are described in the table.

*Reactions*	*What is formed*	*Examples*
With acids	Salt and water. Insoluble bases react only with soluble acids	Cu(OH) 2 ↓ + H 2 SO 4 → CuSO 4 +2H 2 O
High temperature decomposition	Metal oxide and water	2Fe(OH) 3 → Fe 2 O 3 + 3H 2 O
With acidic oxides (alkalis react)		NaOH + CO 2 → NaHCO 3
With non-metals (alkalis enter)	Salt and hydrogen	2NaOH + Si + H 2 O → Na 2 SiO 3 +H 2
Exchange with salts	Hydroxide and salt	Ba(OH) 2 + Na 2 SO 4 → 2NaOH + BaSO 4 ↓
Alkalis with some metals	Complex salt and hydrogen	2Al + 2NaOH + 6H 2 O → 2Na + 3H 2

Using the indicator, a test is carried out to determine the class of the base. When interacting with a base, litmus turns blue, phenolphthalein turns crimson, and methyl orange turns yellow.

Rice. 3. Reaction of indicators to bases.

What have we learned?

From the 8th grade chemistry lesson we learned about the features, classification and interaction of bases with other substances. Grounds - complex substances, consisting of a metal and a hydroxyl group OH. They are divided into soluble or alkali and insoluble. Alkalis are more aggressive bases that react quickly with other substances. Bases are obtained by reacting a metal or metal oxide with water, as well as by the reaction of a salt and an alkali. Bases react with acids, oxides, salts, metals and non-metals, and also decompose at high temperatures.