Metals occupy the bottom left corner of the Periodic Table. Metals belong to the families of s-elements, d-elements, f-elements and, partially, p-elements.

The most typical property of metals is their ability to donate electrons and transform into positively charged ions. Moreover, metals can only exhibit a positive oxidation state.

Me - ne \u003d Me n +

1. Interaction of metals with non-metals.

but ) Interaction of metals with hydrogen.

Alkali and alkaline earth metals react directly with hydrogen to form hydrides.

For example:

Ca + H 2 \u003d CaH 2

Non-stoichiometric compounds with an ionic crystal structure are formed.

b) Interaction of metals with oxygen.

All metals except Au, Ag, Pt are oxidized by atmospheric oxygen.

Example:

2Na + O 2 = Na 2 O 2 (peroxide)

4K + O 2 \u003d 2K 2 O

2Mg + O 2 \u003d 2MgO

2Cu + O 2 \u003d 2CuO

c) Interaction of metals with halogens.

All metals react with halogens to form halides.

Example:

2Al + 3Br 2 = 2AlBr 3

These are mainly ionic compounds: MeHal n

d) Interaction of metals with nitrogen.

Alkali and alkaline earth metals interact with nitrogen.

Example:

3Ca + N 2 \u003d Ca 3 N 2

Mg + N 2 \u003d Mg 3 N 2 - nitride.

e) Interaction of metals with carbon.

Compounds of metals and carbon are carbides. They are formed during the interaction of melts with carbon. Active metals form stoichiometric compounds with carbon:

4Al + 3C \u003d Al 4 C 3

Metals - d-elements form compounds of non-stoichiometric composition such as solid solutions: WC, ZnC, TiC - are used to obtain superhard steels.

2. Interaction of metals with water.

Metals react with water, having a more negative potential than the redox potential of water.

Active metals react more actively with water, decomposing water with the release of hydrogen.

Na + 2H 2 O \u003d H 2 + 2NaOH

Less active metals slowly decompose water and the process is inhibited due to the formation of insoluble substances.

3. Interaction of metals with salt solutions.

Such a reaction is possible if the reacting metal is more active than that in the salt:

Zn + CuSO 4 \u003d Cu 0 ↓ + ZnSO 4

0.76 V., = + 0.34 V.

A metal that has a more negative or less positive standard electrode potential displaces another metal from its salt solution.

4. Interaction of metals with alkali solutions.

Metals can interact with alkalis, giving amphoteric hydroxides or having high degrees oxidation in the presence of strong oxidizing agents. When metals interact with alkali solutions, water is the oxidizing agent.

Example:

Zn + 2NaOH + 2H 2 O \u003d Na 2 + H 2

1 Zn 0 + 4OH - - 2e \u003d 2- oxidation

Zn 0 - reducing agent

1 2H 2 O + 2e \u003d H 2 + 2OH - recovery

H 2 O - oxidizing agent

Zn + 4OH - + 2H 2 O \u003d 2- + 2OH - + H 2

Metals with high oxidation states can interact with alkalis when fused:

4Nb + 5O 2 + 12KOH \u003d 4K 3 NbO 4 + 6H 2 O

5. Interaction of metals with acids.

These are complex reactions, the interaction products depend on the activity of the metal, on the type and concentration of the acid, and on the temperature.

By activity, metals are conditionally divided into active, medium activity and low activity.

Acids are conventionally divided into 2 groups:

Group I - acids with a low oxidizing ability: HCl, HI, HBr, H 2 SO 4 (dil.), H 3 PO 4, H 2 S, the oxidizing agent here is H +. When interacting with metals, oxygen (H 2 ) is released. Metals with a negative electrode potential react with acids of the first group.

Group II - acids with a high oxidizing ability: H 2 SO 4 (conc.), HNO 3 (razb.), HNO 3 (conc.). In these acids, acid anions are oxidizing agents:. The anion reduction products can be very diverse and depend on the activity of the metal.

H 2 S - with active metals

H 2 SO 4 + 6e S 0 ↓ - with metals of medium activity

SO 2 - with low-active metals

NH 3 (NH 4 NO 3) - with active metals

HNO 3 + 4.5e N 2 O, N 2 - with metals of medium activity

NO - with low-active metals

HNO 3 (conc.) - NO 2 - with metals of any activity.

If metals have variable valence, then with group I acids, metals acquire the lowest positive oxidation state: Fe → Fe 2+, Cr → Cr 2+. When interacting with acids of group II, the oxidation state is +3: Fe → Fe 3+, Cr → Cr 3+, while hydrogen is never released.

Some metals (Fe, Cr, Al, Ti, Ni, etc.) in solutions of strong acids, when oxidized, are covered with a dense oxide film, which protects the metal from further dissolution (passivation), but when heated oxide film dissolves and the reaction proceeds.

Slightly soluble metals with a positive electrode potential can dissolve in group I acids in the presence of strong oxidizing agents.

Chemical properties metals: interaction with oxygen, halogens, sulfur and relation to water, acids, salts.

The chemical properties of metals are due to the ability of their atoms to easily donate electrons from the external energy level to become positively charged ions. Thus in chemical reactions metals are energetic reducing agents. This is their main common chemical property.

The ability to donate electrons from individual atoms metal elements different. The more easily a metal gives up its electrons, the more active it is, and the more vigorously it reacts with other substances. Based on the research, all metals were arranged in a row according to their decreasing activity. This series was first proposed by the outstanding scientist N. N. Beketov. Such a series of activity of metals is also called the displacement series of metals or the electrochemical series of metal voltages. It looks like this:

Li, K, Ba, Ca, Na, Mg, Al, Zn, Fe, Ni, Sn, Pb, H2, Cu, Hg, Ag, Рt, Au

Using this series, you can find out which metal is the active of the other. This series contains hydrogen, which is not a metal. Its visible properties are taken for comparison as a kind of zero.

Having the properties of reducing agents, metals react with various oxidizing agents, primarily with non-metals. Metals react with oxygen under normal conditions or when heated to form oxides, for example:

2Mg0 + O02 = 2Mg+2O-2

In this reaction, magnesium atoms are oxidized and oxygen atoms are reduced. The noble metals at the end of the row react with oxygen. Reactions with halogens actively occur, for example, the combustion of copper in chlorine:

Cu0 + Cl02 = Cu+2Cl-2

Reactions with sulfur most often occur when heated, for example:

Fe0 + S0 = Fe+2S-2

Active metals in the activity series of metals in Mg react with water to form alkalis and hydrogen:

2Na0 + 2H+2O → 2Na+OH + H02

Metals of medium activity from Al to H2 react with water under more severe conditions and form oxides and hydrogen:

Pb0 + H+2O Chemical properties of metals: interaction with oxygen Pb+2O + H02.

The ability of a metal to react with acids and salts in solution also depends on its position in the displacement series of metals. Metals to the left of hydrogen in the displacement series of metals usually displace (reduce) hydrogen from dilute acids, and metals to the right of hydrogen do not displace it. So, zinc and magnesium react with acid solutions, releasing hydrogen and forming salts, while copper does not react.

Mg0 + 2H+Cl → Mg+2Cl2 + H02

Zn0 + H+2SO4 → Zn+2SO4 + H02.

Metal atoms in these reactions are reducing agents, and hydrogen ions are oxidizing agents.

Metals react with salts in aqueous solutions. Active metals displace less active metals from the composition of salts. This can be determined from the activity series of metals. The reaction products are a new salt and a new metal. So, if an iron plate is immersed in a solution of copper (II) sulfate, after a while copper will stand out on it in the form of a red coating:

Fe0 + Cu+2SO4 → Fe+2SO4 + Cu0 .

But if a silver plate is immersed in a solution of copper (II) sulfate, then no reaction will occur:

Ag + CuSO4 ≠ .

To carry out such reactions, one should not take too active metals (from lithium to sodium), which are capable of reacting with water.

Therefore, metals are able to react with non-metals, water, acids and salts. In all these cases, the metals are oxidized and are reducing agents. To predict the course of chemical reactions involving metals, a displacement series of metals should be used.

In Lesson 28 " Chemical properties of water» from the course « Chemistry for dummies» learn about the interaction of water with various substances.

Under normal conditions, water is a fairly active substance in relation to other substances. This means that it enters into chemical reactions with many of them.

If a jet of gaseous carbon monoxide (IV) CO 2 ( carbon dioxide) direct into the water, then part of it will dissolve in it (Fig. 109).

At the same time, a chemical reaction of the compound occurs in the solution, as a result of which a new substance is formed - carbonic acid H 2 CO 3:

On a note: Collecting carbon dioxide over water, J. Priestley discovered that part of the gas dissolves in water and gives it a pleasant tart taste. In fact, Priestley was the first to get a drink like soda, or soda.wow, water.

The compound reaction also occurs if a solid is added to water. phosphorus(V) oxide P 2 O 5. In this case, a chemical reaction takes place with the formation phosphoric acid H 3 PO 4(Fig. 110):

Let's test the solutions obtained by the interaction of CO 2 and P 2 O 5 with water, the indicator is methyl orange. To do this, add 1-2 drops of the indicator solution to the resulting solutions. The indicator color will change from orange to Red what says about the presence acids in solutions. This means that during the interaction of CO 2 and P 2 O 5 with water, the acids H 2 CO 3 and H 3 PO 4 were indeed formed.

Oxides like CO 2 and P 2 O 5 , which form acids when interacting with water, are classified as acid oxides.

Acid oxides are oxides to which acids correspond.

Some of the acid oxides and their corresponding acids are listed in Table 11. Note that these are oxides of non-metal elements. Generally, non-metal oxides are acidic oxides.

Interaction with metal oxides

Water reacts differently with metal oxides than with non-metal oxides.

We study the interaction of calcium oxide CaO with water. To do this, place a small amount of CaO in a glass of water and mix thoroughly. In this case, a chemical reaction takes place:

as a result of which a new substance Ca (OH) 2 is formed, belonging to the class of bases. In the same way, oxides of lithium and sodium react with water. At the same time, bases are also formed, for example:

You will learn more about the bases in the next lesson. Metal oxides that correspond to bases are called basic oxides.

Basic oxides are oxides that correspond to bases.

Table 12 lists the formulas for some of the basic oxides and their corresponding bases. Note that, unlike acidic oxides, basic oxides contain metal atoms. Most metal oxides are basic oxides.

Although each basic oxide has a corresponding base, not all basic oxides react with water like CaO to form bases.

Interaction with metals

Under normal conditions, active metals (K, Na, Ca, Ba, etc.) react violently with water:

These reactions release hydrogen and form water-soluble bases.

How chemically active substance water reacts with many other substances, but you will learn about this when you study chemistry further.

Lesson summary:

1. Water is a chemically active substance. It reacts with acidic and basic oxides, active metals.
2. When water reacts with most acidic oxides, the corresponding acids are formed.
3. Some basic oxides react with water to form soluble bases.
4. Under normal conditions, water reacts with the most active metals. This produces soluble bases and hydrogen.

I hope lesson 28 " Chemical properties of water' was clear and informative. If you have any questions, write them in the comments.

1. Metals react with non-metals.

2Me + n Hal 2 → 2 MeHal n

4Li + O2 = 2Li2O

Alkali metals, with the exception of lithium, form peroxides:

2Na + O 2 \u003d Na 2 O 2

2. Metals standing up to hydrogen react with acids (except nitric and sulfuric conc.) with the release of hydrogen

Me + HCl → salt + H2

2 Al + 6 HCl → 2 AlCl3 + 3 H2

Pb + 2 HCl → PbCl2↓ + H2

3. Active metals react with water to form alkali and release hydrogen.

2Me+ 2n H 2 O → 2Me(OH) n + n H2

The product of metal oxidation is its hydroxide - Me (OH) n (where n is the oxidation state of the metal).

For example:

Ca + 2H 2 O → Ca (OH) 2 + H 2

4. Intermediate activity metals react with water when heated to form metal oxide and hydrogen.

2Me + nH 2 O → Me 2 O n + nH 2

The oxidation product in such reactions is metal oxide Me 2 O n (where n is the oxidation state of the metal).

3Fe + 4H 2 O → Fe 2 O 3 FeO + 4H 2

5. Metals standing after hydrogen do not react with water and acid solutions (except for nitric and sulfuric conc.)

6. More active metals displace less active ones from solutions of their salts.

CuSO 4 + Zn \u003d ZnSO 4 + Cu

CuSO 4 + Fe \u003d FeSO 4 + Cu

Active metals - zinc and iron replaced copper in sulfate and formed salts. Zinc and iron are oxidized, and copper is restored.

7. Halogens react with water and alkali solution.

Fluorine, unlike other halogens, oxidizes water:

2H 2 O+2F 2 = 4HF + O 2 .

in the cold: Cl2 + 2KOH = KClO + KCl + H2OCl2 + 2KOH = KClO + KCl + H2O chloride and hypochlorite are formed

heating: 3Cl2+6KOH−→KClO3+5KCl+3H2O3Cl2+6KOH→t,∘CKClO3+5KCl+3H2O forms loride and chlorate

8 Active halogens (except fluorine) displace less active halogens from solutions of their salts.

9. Halogens do not react with oxygen.

10. Amphoteric metals (Al, Be, Zn) react with solutions of alkalis and acids.

3Zn+4H2SO4= 3 ZnSO4+S+4H2O

11. Magnesium reacts with carbon dioxide and silicon oxide.

2Mg + CO2 = C + 2MgO

SiO2+2Mg=Si+2MgO

12. Alkali metals (except lithium) form peroxides with oxygen.

2Na + O 2 \u003d Na 2 O 2

3. Classification of inorganic compounds

Simple substances - substances whose molecules consist of atoms of the same type (atoms of the same element). In chemical reactions, they cannot decompose to form other substances.

Complex Substances (or chemical compounds) - substances whose molecules consist of atoms of different types (atoms of various chemical elements). In chemical reactions, they decompose to form several other substances.

Simple substances are divided into two large groups: metals and non-metals.

Metals - a group of elements with characteristic metallic properties: solids (with the exception of mercury) have a metallic luster, are good conductors of heat and electricity, malleable (iron (Fe), copper (Cu), aluminum (Al), mercury (Hg), gold (Au), silver (Ag), etc.).

non-metals - a group of elements: solid, liquid (bromine) and gaseous substances that do not have a metallic sheen, are insulators, brittle.

And complex substances, in turn, are divided into four groups, or classes: oxides, bases, acids and salts.

oxides - these are complex substances, the composition of the molecules of which includes atoms of oxygen and some other substance.

Foundations - These are complex substances in which metal atoms are connected to one or more hydroxyl groups.

From the point of view of the theory of electrolytic dissociation, bases are complex substances, during the dissociation of which in aqueous solution metal cations (or NH4 +) and hydroxide - anions OH- are formed.

acids - these are complex substances whose molecules include hydrogen atoms that can be replaced or exchanged for metal atoms.

salt - These are complex substances, the molecules of which consist of metal atoms and acid residues. Salt is a product of partial or complete replacement of hydrogen atoms of an acid by a metal.

Foundations – complex substances that consist of a metal cation Me + (or a metal-like cation, for example, an ammonium ion NH 4 +) and a hydroxide anion OH -.

Based on their solubility in water, bases are divided into soluble (alkali) And insoluble bases . Also have unstable grounds that spontaneously decompose.

Getting the grounds

1. Interaction of basic oxides with water. At the same time, they react with water under normal conditions only those oxides that correspond to a soluble base (alkali). Those. this way you can only get alkalis:

basic oxide + water = base

For example , sodium oxide forms in water sodium hydroxide(sodium hydroxide):

Na 2 O + H 2 O → 2NaOH

At the same time about copper(II) oxide from water does not react:

CuO + H 2 O ≠

2. Interaction of metals with water. Wherein react with waterunder normal conditionsonly alkali metals(lithium, sodium, potassium, rubidium, cesium), calcium, strontium and barium.In this case, a redox reaction occurs, hydrogen acts as an oxidizing agent, and a metal acts as a reducing agent.

metal + water = alkali + hydrogen

For example, potassium reacts with water very violent:

2K 0 + 2H 2 + O → 2K + OH + H 2 0

3. Electrolysis of solutions of some alkali metal salts. As a rule, to obtain alkalis, electrolysis is subjected to solutions of salts formed by alkali or alkaline earth metals and anoxic acids (except hydrofluoric) - chlorides, bromides, sulfides, etc. This issue is discussed in more detail in the article .

For example , electrolysis of sodium chloride:

2NaCl + 2H 2 O → 2NaOH + H 2 + Cl 2

4. Bases are formed by the interaction of other alkalis with salts. In this case, only soluble substances interact, and an insoluble salt or an insoluble base should form in the products:

or

lye + salt 1 = salt 2 ↓ + lye

For example: potassium carbonate reacts in solution with calcium hydroxide:

K 2 CO 3 + Ca(OH) 2 → CaCO 3 ↓ + 2KOH

For example: copper (II) chloride reacts in solution with sodium hydroxide. At the same time, it drops blue precipitate of copper(II) hydroxide:

CuCl 2 + 2NaOH → Cu(OH) 2 ↓ + 2NaCl

Chemical properties of insoluble bases

1. Insoluble bases interact with strong acids and their oxides (and some medium acids). At the same time, they form salt and water.

insoluble base + acid = salt + water

insoluble base + acid oxide= salt + water

For example ,copper (II) hydroxide interacts with strong hydrochloric acid:

Cu(OH) 2 + 2HCl = CuCl 2 + 2H 2 O

In this case, copper (II) hydroxide does not interact with acidic oxide weak carbonic acid - carbon dioxide:

Cu(OH) 2 + CO 2 ≠

2. Insoluble bases decompose when heated into oxide and water.

For example, iron (III) hydroxide decomposes into iron (III) oxide and water when calcined:

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

3. Insoluble bases do not interactwith amphoteric oxides and hydroxides.

insoluble base + amphoteric oxide ≠

insoluble base + amphoteric hydroxide ≠

4. Some insoluble bases can act asreducing agents. Reducing agents are bases formed by metals with minimum or intermediate oxidation state, which can increase their oxidation state (iron (II) hydroxide, chromium (II) hydroxide, etc.).

For example , iron (II) hydroxide can be oxidized with atmospheric oxygen in the presence of water to iron (III) hydroxide:

4Fe +2 (OH) 2 + O 2 0 + 2H 2 O → 4Fe +3 (O -2 H) 3

Chemical properties of alkalis

1. Alkalis interact with any acids - both strong and weak . In this case, salt and water are formed. These reactions are called neutralization reactions. Possibly education acid salt, if the acid is polybasic, at a certain ratio of reagents, or in excess acid. IN excess alkali average salt and water are formed:

alkali (excess) + acid \u003d medium salt + water

alkali + polybasic acid (excess) = acid salt + water

For example , sodium hydroxide when interacting with a tribasic phosphoric acid can form 3 types of salts: dihydrophosphates, phosphates or hydrophosphates.

In this case, dihydrophosphates are formed in an excess of acid, or at a molar ratio (the ratio of the amounts of substances) of the reagents 1:1.

NaOH + H 3 PO 4 → NaH 2 PO 4 + H 2 O

With a molar ratio of the amount of alkali and acid of 2: 1, hydrophosphates are formed:

2NaOH + H 3 PO 4 → Na 2 HPO 4 + 2H 2 O

In excess of alkali, or at a molar ratio of alkali and acid of 3:1, an alkali metal phosphate is formed.

3NaOH + H 3 PO 4 → Na 3 PO 4 + 3H 2 O

2. Alkalis interact withamphoteric oxides and hydroxides. Wherein common salts are formed in the melt , but in solution - complex salts .

alkali (melt) + amphoteric oxide = medium salt + water

lye (melt) + amphoteric hydroxide = medium salt + water

alkali (solution) + amphoteric oxide = complex salt

alkali (solution) + amphoteric hydroxide = complex salt

For example , when aluminum hydroxide reacts with sodium hydroxide in the melt sodium aluminate is formed. The more acidic hydroxide forms an acid residue:

NaOH + Al(OH) 3 = NaAlO 2 + 2H 2 O

BUT in solution a complex salt is formed:

NaOH + Al(OH) 3 = Na

Pay attention to how the formula of a complex salt is compiled:first we choose the central atom (toas a rule, it is a metal from amphoteric hydroxide).Then add to it ligands- in our case, these are hydroxide ions. The number of ligands is, as a rule, 2 times greater than the oxidation state of the central atom. But the aluminum complex is an exception, its number of ligands is most often 4. We enclose the resulting fragment in square brackets - this is a complex ion. We determine its charge and add it outside right amount cations or anions.

3. Alkalis interact with acidic oxides. It is possible to form sour or medium salt, depending on the molar ratio of alkali and acid oxide. In excess of alkali, an average salt is formed, and in an excess of acidic oxide, an acid salt is formed:

alkali (excess) + acid oxide \u003d medium salt + water

or:

alkali + acid oxide (excess) = acid salt

For example , when interacting excess sodium hydroxide With carbon dioxide, sodium carbonate and water are formed:

2NaOH + CO 2 \u003d Na 2 CO 3 + H 2 O

And when interacting excess carbon dioxide with sodium hydroxide, only sodium bicarbonate is formed:

2NaOH + CO 2 = NaHCO 3

4. Alkalis interact with salts. alkalis react only with soluble salts in solution, provided that products form gas or precipitate . These reactions proceed according to the mechanism ion exchange.

alkali + soluble salt = salt + corresponding hydroxide

Alkalis interact with solutions of metal salts, which correspond to insoluble or unstable hydroxides.

For example, sodium hydroxide interacts with copper sulfate in solution:

Cu 2+ SO 4 2- + 2Na + OH - = Cu 2+ (OH) 2 - ↓ + Na 2 + SO 4 2-

Also alkalis interact with solutions of ammonium salts.

For example , potassium hydroxide interacts with ammonium nitrate solution:

NH 4 + NO 3 - + K + OH - \u003d K + NO 3 - + NH 3 + H 2 O

! When salts of amphoteric metals interact with an excess of alkali, a complex salt is formed!

Let's look at this issue in more detail. If the salt formed by the metal to which amphoteric hydroxide , interacts with a small amount of alkali, then the usual exchange reaction proceeds, and precipitatesthe hydroxide of this metal .

For example , excess zinc sulfate reacts in solution with potassium hydroxide:

ZnSO 4 + 2KOH \u003d Zn (OH) 2 ↓ + K 2 SO 4

However, in this reaction, not a base is formed, but mphoteric hydroxide. And, as we mentioned above, amphoteric hydroxides dissolve in an excess of alkalis to form complex salts . T Thus, during the interaction of zinc sulfate with excess alkali solution a complex salt is formed, no precipitate is formed:

ZnSO 4 + 4KOH \u003d K 2 + K 2 SO 4

Thus, we obtain 2 schemes for the interaction of metal salts, which correspond to amphoteric hydroxides, with alkalis:

amphoteric metal salt (excess) + alkali = amphoteric hydroxide↓ + salt

amph.metal salt + alkali (excess) = complex salt + salt

5. Alkalis interact with acidic salts.In this case, medium salts or less acidic salts are formed.

sour salt + alkali \u003d medium salt + water

For example , Potassium hydrosulfite reacts with potassium hydroxide to form potassium sulfite and water:

KHSO 3 + KOH \u003d K 2 SO 3 + H 2 O

It is very convenient to determine the properties of acid salts by mentally breaking an acid salt into 2 substances - an acid and a salt. For example, we break sodium bicarbonate NaHCO 3 into uric acid H 2 CO 3 and sodium carbonate Na 2 CO 3 . The properties of bicarbonate are largely determined by the properties of carbonic acid and the properties of sodium carbonate.

6. Alkalis interact with metals in solution and melt. In this case, a redox reaction occurs, in the solution complex salt And hydrogen, in the melt - medium salt And hydrogen.

Note! Only those metals react with alkalis in solution, in which the oxide with a minimum positive degree metal oxidation amphoteric!

For example , iron does not react with an alkali solution, iron (II) oxide is basic. BUT aluminum dissolves in an aqueous solution of alkali, aluminum oxide is amphoteric:

2Al + 2NaOH + 6H 2 + O = 2Na + 3H 2 0

7. Alkalis interact with non-metals. In this case, redox reactions take place. Usually, non-metals disproportionate in alkalis. do not react with alkalis oxygen, hydrogen, nitrogen, carbon and inert gases (helium, neon, argon, etc.):

NaOH + O 2 ≠

NaOH + N 2 ≠

NaOH+C≠

Sulfur, chlorine, bromine, iodine, phosphorus and other non-metals disproportionate in alkalis (i.e. self-oxidize-self-repair).

For example, chlorinewhen interacting with cold alkali goes into oxidation states -1 and +1:

2NaOH + Cl 2 0 \u003d NaCl - + NaOCl + + H 2 O

Chlorine when interacting with hot lye goes into oxidation states -1 and +5:

6NaOH + Cl 2 0 \u003d 5NaCl - + NaCl + 5 O 3 + 3H 2 O

Silicon oxidized by alkalis to an oxidation state of +4.

For example, in solution:

2NaOH + Si 0 + H 2 + O \u003d NaCl - + Na 2 Si + 4 O 3 + 2H 2 0

Fluorine oxidizes alkalis:

2F 2 0 + 4NaO -2 H \u003d O 2 0 + 4NaF - + 2H 2 O

You can read more about these reactions in the article.

8. Alkalis do not decompose when heated.

The exception is lithium hydroxide:

2LiOH \u003d Li 2 O + H 2 O