High School Compulsory Course 1: Chemistry Redox Reactions Knowledge Summary

Increased valency, loss of electrons, oxidation, use as a reducing agent··· Reduced valence·· Get electron·· Restored·· To be an oxidant··· Hee-hee

Redox reactionsFirst, the basic concept1. Redox reaction: all chemical reactions with the rise and fall of the valence of elements (both characteristics and judgment basis).

2. The essence of redox reaction: the gain and loss (or offset) of electrons of atoms or ions.

3. Oxidation reaction: the reaction of losing electrons or sharing electron pairs to deviate.

4. Reduction reaction: the reaction of obtaining electrons or sharing electron pairs bias.

5. Oxidant: a reactant that obtains electrons or shares electron pair bias.

6. Reducing agent: reactants that lose electrons or share electron pairs that deviate.

7. Oxidation products: oxidation reaction occurs in reducing agent'Resultant.

8. Reduction product: the product of the reduction reaction of the oxidant.

Second, the main points of knowledge1. The relationship between redox reactions and basic reaction types.

The displacement reaction must be a redox reaction;

The metathesis reaction must not be a redox reaction (i.e., a non-redox reaction);

Knowledge points: 1. The relationship between the concepts of redox reaction.

1. Reaction type:

Oxidation reaction: A reaction in which the valency of the elements contained in a substance increases.

Reduction reaction: A reaction in which the valency of the elements contained in a substance decreases.

Redox reaction: There is a reaction in which the valency of the elements increases and decreases.

2. Reactants:

Oxidant: A substance that gives electrons in a reaction.

Reducing agent: A substance that loses electrons in a reaction.

3. Product: Oxidation product: the product obtained after the loss of electrons is oxidized.

Reduction product: The product obtained after the electrons are reduced.

4. Material properties:

Oxidizing: The properties of the electrons exhibited by the oxidizing agent.

Reducibility: The electron-losing property exhibited by the reducing agent.

2. Common oxidants and reducing agents.

1. Whether a substance is used as an oxidant or a reducing agent in the reaction mainly depends on the valency of the element.

1) When the element is at its most, its atoms can only get electrons, so the element can only be used as an oxidant, such as +7-valent Mn and +6-valent S

2) When the element is in the intermediate valence state, its atoms can both gain and lose electrons with different reaction conditions, so the element can be used as both an oxidant and a reducing agent, such as 0-valent S and +4-valent S

3) When an element is at its lowest valence, its atom can only lose electrons, so the element can only be used as a reducing agent, such as -2 valence s

2. Important oxidizing agent.

1) Active non-metallic elements, such as F2, Cl2, Br2, O2, etc.

2) Oxides, oxygenated acids and oxides when the elements are in **, such as mNO2 and NO2; concentrated H2SO4, HNO3; KMNO4, KCLO3, FeCl3, etc.

3) Peroxides, such as Na2O2, H2O2, etc.

1. The basic concept of redox reaction:

Oxidation and reduction reactions: oxidation reactions are characterized by an increase in the valency of an oxidized element, which is essentially a process in which the atoms of the element lose electrons (or deviate from the common electron pairs); The reduction reaction is characterized by a decrease in the valency of the reduced element, which is essentially the process by which the atoms of the element gain electrons (or share electron pair bias).

2. Oxidation products and reduction products: generated by oxidation. Substances are oxidation products, and the substances that are reduced to form are reduction products.

Common oxidants are O2, Cl2, concentrated sulfuric acid, HNo3, KmNO4, FeCl3, etc.; Common reducing agents are active metal element, H2, C, CO, etc.

3. Representation of electron transfer in redox: the direction and number of electron transfer are expressed by using a two-wire bridge or a single-wire bridge, the difference between the two is that the use of a two-wire bridge needs to mark the gains and losses of electrons, while a single-wire bridge does not.

4. The balancing of the redox reaction equation is a difficult point, and most of the problems can be solved by mastering the skills required for the equalization of valence and elevation of valence.

Common test methods

The basic concepts of redox reactions and the representation of electrons gained and lost are often examined in the form of multiple-choice questions and fill-in-the-blank questions. The trim of redox reactions and related calculations are examined in the form of ** questions.

Misunderstanding warning

This is a method to compare the oxidation and reducibility of substances.

According to the chemical equation of the redox reaction: in a redox reaction, oxidation: oxidant" oxidation product; Reducibility:

Reducing agent》 reducing product. According to the order of metal activity: the stronger the metal activity, the stronger its reducibility, that is:

Reducibility: K>Ca>Na>Mg>Al>ZN>Fe>SN>Pb>(H)>Cu>Hg>Ag

The stronger the reducibility of a metal, the less oxidizing the metal ions formed after it loses electrons, i.e.:

Oxidation: K+

Fe3+ can react with copper: 2Fe3++ Cu = 2Fe2++ Cu2+, so oxidation: Fe3+> Cu2+.

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