Acids as electrolytes, their classification according to various criteria.

Acids are called complex substances, the molecules of which consist of hydrogen atoms and an acid residue.

Recall what we already know about acids and their classification.

We found out that there are several classifications of acids, as well as signs of classification. But no matter how different they are, all acids form hydrogen cations during dissociation, which determine a number of common properties: sour taste, discoloration of indicators (demonstration experiment acid + indicators), interaction with other substances. In the past lessons, we met you with TED, so let’s write down the definition of acids from the standpoint of this theory.

Acids are called electrolytes, which, upon dissociation, form hydrogen cations and anions of the acid residue.

Independent work with the textbook: Chemistry for professions and specialties of a technical profile: a textbook for students. medium institutions. prof. education / O.S.Gabrielyan, I.G. Ostroumov, page 73. – consider the classification of acids.

Chemical properties of acids in the light of the theory of electrolytic dissociation.

The main chemical properties are considered in the form of a scheme presented in the textbook:

1. Acid + metal → salt + hydrogen

(substitution reaction)

These reactions proceed when several conditions are met:

if the metals are in the series of activity of metals up to hydrogen;

as a result of the reaction, a soluble salt should be obtained, if an insoluble salt is formed, then a film of this salt is formed on the surface of the metal, which stops the access of the acid to the metal;

insoluble silicic acid does not interact with metals;

nitric and concentrated sulfuric acids especially interact with metals, but we will talk about this in grade 9.

Al + 3 H 2 SO 4 u003d Al 2 (SO 4 ) 3 + H 2

Al 0 + 6H + + 3SO 4 2- = 2Al 3+ + 3SO 4 2- + H 2

Al 0 + 3SO 4 2- = 2Al 3+ + H 2

Cu + 2HCl ≠

2. Acid + base → salt + water (neutralization reaction)

(exchange reaction)

This reaction is universal and proceeds between any acid and between any base.

HCl + NaOH u003d NaCl + H 2 O

H + + Cl + Na + + OH = Na + + Cl + H 2 O

H + + OH u003d H 2 O

The reaction between an insoluble base and an acid is proposed to be written by the guys on their own (molecular, complete and abbreviated ionic), the first one to make it receives an assessment:

Fe(OH) 2 + H 2 SO 4 = FeSO 4 + 2H 2 O

Fe(OH) 2 + 2H + + SO 4 2- = Fe 2+ + SO 4 2- + 2H 2 O

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

3. Acid + metal oxide → salt + water

(exchange reaction)

When compiling this equation, draw the attention of students to the fact that metal oxides are not electrolytes, therefore, in the ionic equation it is written in molecular form (multimedia textbook “Chemistry. Grade 8” No. 5, 6).

CuO + H 2 SO 4 u003d CuSO 4 + 2H 2 O

CuO + 2H + + SO 4 2- = Cu 2+ + SO 4 2- + 2H 2 O

CuO + 2H + = Cu 2+ + 2H 2 O

This type of reaction takes place in the case of the formation of a soluble salt, if an insoluble salt is formed, then a film of this salt is formed on the surface of the metal, which stops the access of the acid to the oxide.

4. Acid + salt → new acid + new salt

(exchange reaction)

The interaction of acids with salts is a typical exchange reaction and proceeds according to the same patterns, i.e. in case of formation of sediment, gas or weak electrolyte.

Al 2 (CO 3 ) 3 + 3H 2 SO 4 u003d Al 2 (SO 4 ) 3 + 3H 2 O + 3CO 2

2Al 3+ + 3CO 3 2- + 6H + + 3SO 4 2- = 2Al 3+ + 3SO 4 2- + 3H 2 O + 3CO 2

3CO 3 2- + 6H + = 3H 2 O + 3CO 2

Features of the interaction of concentrated sulfuric and nitric acids with metals.

Independent work with the textbook: Chemistry for professions and specialties of a technical profile: a textbook for students. medium institutions. prof. education / O.S.Gabrielyan, I.G. Ostroumov, page 74.

The main methods for obtaining acid.

– oxygen-free acids are obtained by the interaction of hydrogen with non-metals (with subsequent dissolution in water):

Cl2 + H2 = 2HCl;

H2 + S = H2S;

– – interaction of acid oxides with water:

N2O5 + H2O = 2HNO3;

P2O5 + 3H2O = 2H3PO4;

– – the interaction of salts with acids (the action of a strong or less volatile acid on a salt of a weaker acid or more volatile acid):

H2SO4 + NaCl(TV) = HCl + NaHSO4;

Na2SiO3 + 2HCl = H2SiO3¯ + 2NaCl;

– – oxidation of simple substances:

2P + 5HNO3 + 2H2O = 3H3PO4 + 5NO;

Br2 + 5Cl2 + 6H2O = 2HBrO3 + 10HCl.

Questions for self-control

¾ Define the class of acids.

¾ Name the following acids: HCl, HNO 3 , H 2 SO 4 , H 3 PO 4 , H 2 S, H 2 CO 3 .

¾ There are a lot of acids, but can they be classified.

¾ What classifications do you know.

¾ What groups are acids divided into by composition, by basicity, by strength (give examples).

¾ List the main physical properties inherent in almost all inorganic acids.

¾ Which substances react with each other? Choose the correct answers:

a) CuO + HCl = …;
b) Cu + HCl = …;
c) CuSO 4 + HCl = …;
d) CuCO 3 + HCl = …

¾ Write the equations of possible reactions (molecular and abbreviated ionic.

¾ Which substances react with each other? Choose the correct answers:

a) Al + 3 H 2 SO 4 ( diff ) =;
b) HNO 3 + CuSO 4 =;
c) Al 2 (CO 3 ) 3 + 3H 2 SO 4 =;
d) SO 3 + H 2 SO 4 =

¾ Write the equations of possible reactions (molecular and abbreviated ionic.

¾ Answer the questions of the textbook: Chemistry for professions and specialties of a technical profile: a textbook for students. medium institutions. prof. education / O.S.Gabrielyan, I.G. Ostroumov, page 77.

LESSON PLAN #14

Discipline: Chemistry.

Subject: Foundations.

The purpose of the lesson: to consolidate students’ knowledge about the properties, methods of obtaining and classifying bases.

Planned results

Subject: the formation of ideas about the place of chemistry in the modern scientific picture of the world; possession of fundamental chemical concepts, theories, laws and regularities; confident use of chemical terminology and symbols;

Meta-subject: the use of various sources to obtain chemical information, the ability to assess its reliability in order to achieve good results in the professional field;

Personal: willingness to continue education and advanced training in the chosen professional activity and an objective awareness of the role of chemical competencies in this;

Time limit: 2 hours

Type of lesson: Lecture.

Lesson plan:

1. Bases as electrolytes, their classification according to various criteria.

2. Chemical properties of bases in the light of the theory of electrolytic dissociation. Decomposition of water-insoluble bases.

3. The main methods of obtaining bases.

Equipment: Textbook.

Literature:

1. Chemistry grade 11: textbook. for general education organizations G.E. Rudzitis, F.G. Feldman. – M.: Enlightenment, 2014. -208 p.: Ill..

2. Chemistry for professions and specialties of a technical profile: a textbook for students. medium institutions. prof. education / O.S.Gabrielyan, I.G. Ostroumov. – 5th ed., erased. – M .: Publishing Center “Academy”, 2017. – 272 pp., with color. ill.

Lecturer: Tubaltseva Yu.N.

Topic 14. Grounds.

Plan:

1. Bases as electrolytes, their classification according to various criteria.

2. Chemical properties of bases in the light of the theory of electrolytic dissociation. Decomposition of water-insoluble bases.

3. The main methods of obtaining bases.

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