Reaction 1. Metal + acid \u003d salt + hydrogen

Reaction type - substitution reaction.
A symptom of a reaction is gas evolution.

P when drawing up the reaction equations, do not forget that hydrogen is released in the form of diatomic H2 molecules!

Feasibility - Two conditions must be met:
1) with acids (except for nitric and concentrated sulfuric), only metals that are in the range of activities of metals to hydrogen react (see diagram);
2) in the reaction of metals hydrogen does not evolve with nitric and concentrated sulfuric acids, these acids act on metals according to their own laws. Silicic acid does not react with metals at allbecause it does not dissolve in water.

Example:With which of the listed substances does hydrochloric (hydrochloric) acid react: Na 2 O, Cu, SO 3, Zn? Draw up equations of possible reactions.

1. We determine the belonging of the substances specified in the conditions to the corresponding classes and immediately check whether they react with acids. It turns out:

Na 2 O - basic oxide - reacts (salt and water are obtained);

Cu, a metal in the line of activity after hydrogen, does not react;

SO3 - acidic oxide - does not react;

Zn - a metal in the range of activity up to hydrogen - reacts (salt and hydrogen are obtained).

2. To compose the reaction equations, we determine the valence of metals (sodium - I, zinc - II) and compose the salt formulas, taking into account that the valence of the acid residue Сl is I. It remains to write down the reaction equations:

Na 2 O + 2HCl \u003d 2NaCl + H 2 O;
Zn + 2HCl \u003d ZnCl 2 + H 2.

Reaction 2.basic oxide + acid \u003d salt + water
Reaction type - exchange reaction.
It is easier to form the equation for this reaction than the equation for reaction 1, because we already know the acid formula; knowing it, it is easy to obtain both the formula of the acid residue and its valence.
Next, we do the same as in the previous example. When drawing up the reaction equation, let's not forget that water is released!

Example: Write the equation for the reaction between aluminum oxide and hydrochloric acid.

1. Let's remember the formula of hydrochloric acid - HCl, its remainder Cl (chloride) has valence I.
2. According to the periodic system of D.I. Mendeleev, we will establish that the valence of aluminum III and the formula of its oxide Al2Oz.
3. Let's compose the formula of the reaction product - salt (aluminum chloride): АlСlз.
4. Let us write down the reaction equation and select the coefficients in it:

Al2Oz + 6HCl \u003d AlCl3 + 3H2O

Reaction 3. Base + acid \u003d salt + water

This reaction has a special name - neutralization reaction, because in the course of it, the acid and the base seem to be mutually destroyed.

Reaction type - exchange reaction.

Signs of reaction: heat release, change in color of the indicator, for insoluble hydroxides - disappearance of the precipitate.

To draw up the equation for the neutralization reaction, you need to do the following:

1) determine the valencies of the metal and acid residue;

2) draw up a formula for the resulting salt;

3) write down the reaction equation and select the coefficients.

(photo how a clear solution is obtained from a raspberry solution when acid is added; photo2 - acid was added to the blue precipitate and it dissolved)

The reaction between an acid and a base resulting in the formation of salt and water is called a reaction neutralization .

NaOH + HCl \u003d NaCl + H 2 O

Reaction 4. Acid + salt \u003d new acid + new salt

Reaction type - exchange reaction.
Signs of a reaction are precipitation or gas evolution. Feasibility: The reaction is possible if an insoluble salt is obtained (see solubility table) or an insoluble, unstable or volatile acid.

Good to know: that among the most important acids contained in the table:

• insoluble - silicon (H 2 SiO 3);
• unstable - coal (H 2 COz \u003d H 2 O + CO 2) and sulfur (H 2 SO 3 \u003d H 2 O + SO 2);
• volatile - hydrogen sulfide (H 2 S), as well as НСl, HBr, HI, НNОз - but only in the absence of water and when heated.

To compose the reaction equation, you need to do the following operations:
1) draw up a reaction scheme, for which to determine the formulas of the resulting salt and acid (the solubility table or knowledge of the valence will best help in this);
2) check the condition of the feasibility of the reaction (the table will help with this);
3) if the reaction is feasible, write down the reaction equation. If carbonic or sulfurous acids are obtained, immediately record the products of their decomposition (oxide and water).

HCl + AgNO 3 \u003d AgCl â + HNO 3

Do the suggested exercises:

1. Complete the reaction equations and select the coefficients:
a) CaO + HsPO4 -\u003e b) Na2O + H2CO3 -\u003e
c) Fe2O3 + H2SO4 -\u003e d) ZnO + HNO3 -\u003e
2. Make up the equations of reactions between substances: a) hydroiodic acid and barium oxide; b) sulfuric acid and iron (III) oxide; c) nitric acid and lithium oxide; d) phosphoric acid and potassium oxide.

"Classification of acids" - Classification of acids by the number of hydrogen atoms. Acids. Boric acid. Classification of acids. Hydrogen fluoride. Acid recognition. Complex substances. Food. Characterization of acids. Acetic acid. Groups. Ant bites. Safety regulations. What unites us. Hydrochloric (hydrochloric) acid.

Grade 8 Acids - What acid is added to drinks to add a sour taste? What class of substances can an acid be obtained from? What acid is found in gastric juice? Remember what we know about acids by example. Metal (non-metal) Salt-forming (non-salt-forming) Acidic (basic). Characterize the oxides.

"Organic acids" - Lemon acid obtained from the leaves of tobacco and cotton. Lactic acid. In ancient times, acetic acid was known as aqueous solutions... Lactic acid in the food industry. Acetic acid in industry. Formic acid in nature. Citric acid in production. Choose a section.

"Acid reactions" - BaCL2 + H2SO4 \u003d BaSO4 + 2HCL Ba2 + + SO42- \u003d BaSO4. Typical acid reactions. Acids. Classification of acids. Check yourself. Generalization. Answers.

"Chemistry Grade 8 Acids" - Acids. The value of acids. Apple acid. Acids in nature. Table vinegar. HCN. Safety regulations for working with acids. Change in color of indicators in acid solutions. Acids: composition, classification, meaning. Lemon acid. Poisonous acid. Classification of acids by oxygen content.

"Acids and Water" - The ant injects a venom containing formic acid into the bite wound. Acids in the animal kingdom. A tropical spider shoots a trickle of liquid containing 84% acetic acid at enemies. Acids in the human body. Acetic. Hence the historical name of sulfuric acid - vitriol oil. Some beetles shoot out a trickle of dilute sulfuric acid.

By chemical composition salts are classified into medium, sour, basic and double.

A separate type of salt is complex salts (salts with complex cations or anions). In the formulas of these salts, the complex ion is enclosed in square brackets.
Complex ions - these are complex ions, consisting of ions of an element (complexing agent) and several molecules or ions (ligands) associated with it.

Examples of complex salts are given below.
a) C complex anion:

K 2 [PtC l] 4 - tetrachloroplatinate (II) potassium,
K 2 [PtCl ] 6 - hexachloroplatinate (Iv) potassium,

K 3 [Fe (CN ) 6] - hexacyanoferrate (III) potassium.

B) C complex cation:

[Cr (NH 3) 6] Cl 3 - hexaamminechrome chloride (III),

[Ag (NH 3) 2] Cl - diamminesilver chloride (I)
[Cu (NH 3) 4] SO 4-tetraamminecopper sulfate (II)

Soluble salts, when dissolved in water, dissociate into metal cations and anions of acid residues.
NaCl → Na + + Cl -
K 2 SO 4 → 2K + + SO 4 2-
Al (NO3) 3 → Al 3+ + 3NO 3 -

1. Metal + non-metal \u003d salt
2Fe + 3Cl 2 \u003d 2FeCl 3

2. Metal + acid \u003d salt + hydrogen
Zn + 2HCl \u003d ZnCl 2 + H 2

3. Metal + salt \u003d other metal + other salt
Fe + CuSO 4 \u003d Cu + FeSO 4

4. Acid + basic (amphoteric) oxide \u003d salt + water
3H 2 SO 4 + Al 2 O 3 \u003d Al 2 (SO 4) 3 + 3H 2 O

5. Acid + base \u003d salt + water
H 2 SO 4 + 2NaOH \u003d Na 2 SO 4 + 2H 2 O
With incomplete neutralization of a polybasic acid with a base, sour salt:
H 2 SO 4 + NaOH \u003d NaHSO 4 + H 2 O
With incomplete neutralization of a polyacid base with an acid, basic salt:
Zn (OH) 2 + HCl \u003d ZnOHCl + H 2 O

6. Acid + salt \u003d other acid + other salt (a stronger acid is used for this reaction)
AgNO 3 + HCl \u003d AgCl + HNO 3
BaCl 2 + H 2 SO 4 \u003d BaSO 4 + 2HCl

7. Basic (amphoteric) oxide + acid \u003d salt + water
CaO + 2HCl \u003d CaCl 2 + H 2 O

8. Basic oxide + acidic oxide \u003d salt
Li 2 O + CO 2 \u003d Li 2 CO 3

9. Acid oxide + base \u003d salt + water
SO3 + 2NaOH \u003d Na 2 SO 4 + H 2 O

10. Alkali + salt \u003d base + other salt
CuSO 4 + 2NaOH \u003d Cu (OH) 2 + Na 2 SO 4

11. The exchange reaction between salts: salt (1) + salt (2) \u003d salt (3) + salt (4)
NaCl + AgNO 3 \u003d Na NO 3 + AgCl

12. Acidic salts can be obtained by the action of an excess of acid on medium salts and oxides:
Na 2 SO 4 + H 2 SO 4 \u003d 2NaHSO 4
Li 2O + 2H 2 SO 4 \u003d 2LiHSO 4 + H 2 O

13. Basic salts obtained by carefully adding small amounts of alkalis to solutions of medium salts:
AlCl 3 + 2NaOH \u003d Al (OH) 2 Cl + 2NaCl

1. Salt + alkali \u003d other salt + other base
CuCl 2 + 2KOH \u003d 2KCl + Cu (OH) 2

2. Salt + acid \u003d other salt + other acid
BaCl 2 + H 2 SO 4 \u003d BaSO 4 + 2HCl

3. Salt (1) + salt (2) \u003d Salt (3) + salt (4)
Na 2 SO 4 + BaCl 2 \u003d 2NaCl + BaSO 4

4. Salt + metal \u003d other salt + other metal (according to the electrochemical series of metal voltages)
Zn + Pb (NO 3) 2 \u003d Pb + Zn (NO 3) 2

5. Some salts decompose when heated
CaCO 3 \u003d CaO + CO 2
KNO 3 \u003d KNO 2 + O 2

The specific chemical properties of salts depend on which cation and which anion form a given salt.

Exercise 1. From the list, select salts, name them, determine the type.
1) KNO 2 2) LiOH 3) CaS 4) CuSO 4 5) P 2 O 5 6) Al (OH) 2 Cl 7) NaHSO 3 8) H 2 SO 4

Task 2.With which of the listed substances can a) BaCl 2 b) CuSO 4 c ) Na 2 CO 3?
1) Na 2 O 2) HCl 3) H 2 O 4) AgNO 3 5) HNO 3 6) Na 2 SO 4 7) BaCl 2 8) Fe 9) Cu (OH) 2 10) NaOH

With dilute acids, which exhibit oxidizing properties due tohydrogen ions(diluted sulfuric, phosphoric, sulfurous, all oxygen-free and organic acids, etc.)

metals react:
located in a series of voltages to hydrogen(these metals are able to displace hydrogen from the acid);
forming with these acids soluble salts(no protective salt is formed on the surface of these metals
film).

As a result of the reaction, soluble saltsand stands out hydrogen:
2A1 + 6HCI \u003d 2A1C1 3 + ZN 2
Mg + H 2 SO 4 \u003d M gS О 4 + Н 2
broken.
FROMu + H 2 SO 4 → X (since C u stands after H 2)
broken.
Pb + H 2SO 4 → X (since PL SO 4 insoluble in water)
broken.
Some acids are oxidizing agents due to an element that forms an acid residue, These include concentrated sulfuric acid, as well as nitric acid of any concentration. Such acids are called oxidizing acids.

The oxidizing properties of acid residues are much stronger than the hydrogen non H, therefore, nitric and concentrated sulfuric acids interact with almost all metals located in a series of voltages both before and after hydrogen, except goldand platinum.Since the oxidizing agents in these cases are the nones of acidic residues (due to the sulfur and nitrogen atoms in the higher oxidation states), and not the hydrogen nones H, then in the interaction of nitric and concentrated sulfuric acidsfrom no hydrogen is released by metals.The metal under the action of these acids is oxidized to characteristic (stable) oxidation stateand forms a salt, and the acid reduction product depends on the activity of the metal and the degree of dilution of the acid

Interaction of sulfuric acid with metals

Diluted and concentrated sulfuric acids behave differently. Diluted sulfuric acid behaves like regular acid. Active metals in the series of voltages to the left of hydrogen

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

displace hydrogen from dilute sulfuric acid. We see hydrogen bubbles when adding dilute sulfuric acid to a zinc tube.

H 2 SO 4 + Zn \u003d Zn SO 4 + H 2

Copper is among the stresses after hydrogen - therefore, dilute sulfuric acid does not affect copper. And in concentrated sulfuric acid, zinc and copper behave this way ...

Zinc as an active metal can form with concentrated sulfuric acid, sulfur dioxide, elemental sulfur, and even hydrogen sulfide.

2H 2 SO 4 + Zn \u003d SO 2 + ZnSO 4 + 2H 2 O

Copper is a less active metal. When interacting with concentrated sulfuric acid, it reduces it to sulfur dioxide.

2H 2 SO 4 conc. + Cu \u003d SO 2 + CuSO 4 + 2H 2 O

In test tubes with concentrated sulfuric acid releases sulfur dioxide.

It should be borne in mind that the diagrams indicate the products, the content of which is maximum among the possible products of acid reduction.

Based on the above schemes, we will compose the equations of specific reactions - the interaction of copper and magnesium with concentrated sulfuric acid:
0 +6 +2 +4
FROMu + 2Н 2 SO 4 \u003d С uSO 4 + SO 2 + 2Н 2 O
conc.
0 +6 +2 -2
4Mg + 5H 2 SO 4 \u003d 4M gSO 4 + H 2 S + 4H 2 O
conc.

Some metals ( Fe... AI, Cr) do not interact with concentrated sulfuric and nitric acids at normal temperatures, so how is it going passivationmetal. This phenomenon is associated with the formation of a thin but very dense oxide film on the metal surface, which protects the metal. For this reason, nitric and concentrated sulfuric acids are transported in iron containers.

If the metal exhibits variable oxidation states, then with acids, which are oxidizing agents due to H + ions, it forms salts in which its oxidation state is lower than stable, and with oxidizing acids, salts in which its oxidation state is more stable:
0 +2
F e + H 2 SO 4 \u003d F e SO 4 + H 2
0 split + 3
F e + H 2 SO 4 \u003d F e 2 (SO 4) 3 + 3 SO 2 + 6H 2 O
end

I.I.Novoshinsky
N.S.Novoshinskaya