What are the methods for judging the strength of oxidative reduction?

1. Judge according to the order of metal activities

The reducibility of elemental matter gradually decreases

k ca na mg al zn fe sn pb (h) cu hg ag pt au

The oxidation of the ions gradually increases

2. According to the periodic table, the reductivity gradually weakens and the oxidation gradually increases from left to right in the same period;

The reducibility of the same main group gradually increased from top to bottom, and the oxidation gradually decreased.

3. Judge according to the direction of redox reaction

Strong Oxidant + Strong Reducing Agent = Weak Reducing Agent + Weak Oxidant, simply say "left" and "right". Namely:

Order of oxidation intensity: The oxidation of the oxidant is stronger than the oxidation of the oxidation product.

Order of reducibility: The reducibility of the reducing agent is stronger than that of the reducing product.

For example, based on: 2Fe2++Cl2=2Fe3++2Cl-;

hclo+hcl=cl2+h2o；

2fe3++cu=2fe2++cu2+；

fe+cu2+=fe2++cu

It can be seen that the oxidation from strong to weak is as follows: HClo Cl2 Fe3+ Cu2+ Fe2+

4. Judge according to the reaction conditions.

The easier the reaction conditions, the stronger the oxidation of the oxidizing agent or the reducing agent of the reducing agent.

For example: for the reaction mno2+4HCl==mnCl2+2H2O+Cl2, 2kmNO4+16HCl=2kCl+2mnCl2+8H2O+5Cl2, 4HCl+O2=CuCl2 450=2H2O+2Cl2

According to the reaction conditions, the oxidation strength of the oxidant can be judged in the order of KMno4 Mno2 O2

5. Judge according to the degree of oxidation or reduction.

For example: 2Cu+O2= =2Cuo 2Cu+S= =Cu2S

Depending on the degree of oxidation of copper (+2 valence, +1 valence, respectively), it can be judged that oxygen is more oxidizing than sulfur.

6. The oxidation or reduction of some oxidants is also related to the following factors:

1) Temperature: The oxidation of strong hot concentrated sulfuric acid is stronger than that of cold concentrated sulfuric acid;

2) Concentration: such as oxidation: concentrated Hno3 dilute Hno3

Reducibility: Concentrated HCl Dilute HCl

3) Acidity and alkalinity: For example, the oxidation of potassium permanganate solution is enhanced with the enhancement of the acidity of the solution. In general, potassium permanganate is reduced to Mn2+ under acidic conditions, to MnO2 under neutral conditions, and to MnO42- under alkaline conditions.

1) Utilization valency: Generally speaking, the higher the valency of an element, the greater the possibility of its reduction and the stronger the oxidation; The lower the valency of the element, the greater the possibility of its elevation and the stronger the reduction.

2) Comparison with the same reducing agent or oxidant.

2Fe+3Cl2 ==2FeCl3 Fe+S==Fes oxidizing Cl2 S

Fe+2HCl==FeCl2+H2 mg+2HCl== MgCl2+H2 reducing mg Fe

3) Redox reactions.

Oxidation: Oxidant Oxidation Products Reducibility: Reducing Agents Reducing Products.

4) Order of metal activity: the stronger the reduction of the metal, the weaker the oxidation of the corresponding ions.

Oxidation: K ca na ......AU decreases sequentially.

Reducibility: K+ Ca2+ Na+ ....AG+ is enhanced sequentially.

5) According to the reaction conditions.

H2+F2: Dark contact can be both ** H2+Cl2: Light or ignition, the product is relatively stable.

H2+BR2: Heated to a certain temperature H2+I2: Heated continuously, and the product is unstable.

Oxidation: F2 Cl2 B2 I2

There is and only one kind, redox potential.

Oxidation: The oxidation product is smaller than that of the oxidant; Reducibility: The reducing product is smaller than the reducing agent.

Oxidation, a method for judging the strength of reducibility.

1) Judging according to the chemical equation.

1) Oxidant (oxidizing) + reducing agent (reducing) = = reducing product + oxidation product.

Oxidants --- reduction products.

Electrons are obtained, the valency decreases, they are reduced, and a reduction reaction occurs.

Reducing agents --- oxidation products.

Electrons are lost, valency increases, is oxidized, and oxidation reactions occur.

Oxidation: Oxidizing agent" oxidation product.

Reducibility: Reducing agent" reducing product.

2) It can be judged according to the oxidant and reducing agent in the same reaction.

Oxidizing: Oxidizing agent" reducing agent.

Reducibility: Reducing agent》 Oxidant.

2) Comparison according to the material live rent stupid shouting order of the gear.

1) For metal reducing agents, the reducibility of metal elements is generally consistent with the order of metal activity, that is, the more metal is located behind, the less likely it is to lose electrons, and the weaker the reducibility.

Reducibility: K>Ca>Na>Mg>Al>Mn>Zn>Cr>Fe>Ni>Sn>Pb>(H)>Cu>Ag>PT>AU

2) The order of oxidation of metal cations.

k+mno2>o2

4) Judge according to the valence of oxidation products.

When the reducing agent containing valence elements acts on different oxidants under similar conditions, the oxidation strength of the oxidant can be judged according to the valence state of the oxidation products. Such as:

2Fe+3Cl2== (ignition) 2FeCl3

Fe+S== (heated) Fes

Oxidation: Cl2>s

5) Judging according to the periodic table.

1) Elements of the same main family (from top to bottom).

The oxidation of non-metal atoms (or elementals) gradually decreases, and the corresponding anion reduction gradually increases.

The reducibility of metal atoms gradually increases, and the oxidation of corresponding cations gradually decreases.

2) Synchronous main group elements (from left to right).

The elemental reducibility is gradually enhanced, and the oxidation is gradually enhanced.

The cation oxidation gradually increased, and the anion reduction gradually decreased.

6) Comparison of the acidity and alkalinity of hydrates according to the most ** oxides of the elements.

The more acidic it is, the more oxidizing the corresponding element is.

The stronger the alkalinity, the stronger the reduction of the corresponding element.

7) Judged according to the electrode reaction of the galvanic battery.

Two different metals make up the poles of a galvanic cell. The negative metal is the pole where electrons flow out, and the positive metal is the pole where electrons flow in.

Its reducibility: negative metal》 positive metal.

8) Judged according to the concentration of the substance.

The greater the concentration of an oxidizing (or reducing) substance, the stronger its oxidizing (or reducing) and vice versa.

9) Judge according to the valence state of the element.

Generally speaking, valence elements are only oxidized when they are in the most ** state, only reducing when they are in the lowest valence state, and both oxidizing and reducing when they are in the intermediate valence state. Generally, when it is in the most advanced state, the oxidation is the strongest, and with the decrease of the valency, the oxidation weakens and the reduction is enhanced.

Judgment of the strength of oxidation and reduction:

1. Judged according to the ability to lose electrons.

The ability to lose electrons gradually decreases, and the reducibility gradually decreases. Its cationic electron-gaining ability gradually increases, and its oxidation gradually increases. That is, the more active the metal is, the stronger the reducibility, and the weaker the corresponding cation oxygenation.

2. Judge according to the sequence of non-metallic activities.

The more active the non-metal, the stronger the oxidation, and the weaker the corresponding anion reduction.

3. Judging according to the periodic table.

In the same cycle: from left to right, the oxidation of the elemental elements formed by the elements gradually increases, and the reducibility gradually decreases; The same main group: from top to bottom, the oxidation of the elemental matter formed by the elements gradually decreases, and the reducibility gradually increases; The oxidation of the corresponding cation gradually decreases, and the reducibility of the anion gradually increases.

4. Judge according to the reaction conditions.

The easier the reaction between different reducing agents and the same oxidant, the stronger the reducing ability of the reducing agent. Different oxidants react with the same reducing agent, the easier the reaction, the stronger the oxidizing properties of the oxidant.

Oxidizing substances:

Oxidizing substance refers to a chemically active substance that may not be burned by itself, but can release oxygen, which may cause or promote the combustion of other substances. It often refers to substances containing ** state atomic structure and substances containing hydrogen structure in inorganic compounds. It generally does not burn on its own.

However, if it encounters acid or is exposed to moisture, strong heat, or contact with other reducing substances and flammable substances, it can carry out oxidative decomposition reaction, release heat and oxygen, cause the combustion of combustible substances, and sometimes form a first-class mixture.

Methods for judging the strength of reductivity:

1. Using valency to compare the oxidation and reducing strength of the substance, the strength of the oxidation and reduction of different valence substances formed by the same element is: the lowest valence state of the element only has reduction, and the intermediate valence state of the element has both oxidation and reduction.

2. Use the different activity of elements to compare the strength of oxidation and reduction of substances. For metals, the more reactive the metal (the stronger the metalicity), the stronger the reduction of its elemental matter. For non-metals, the more active the non-metals are (the stronger the non-metals), the weaker the reducing properties of the anions.

3. Use redox reaction to compare the oxidation and reducing strength of the substance, and the general redox reaction, reducibility: reducing agent reduction product. For galvanic cell reactions, there are:

Reducibility Comparison: Anode Material Cathode Material. In the case of electrolysis reactions, the more easily discharged (electron-loss) anions at the anode during electrolysis in the same electrolyte solution, the stronger their reducibility.

4. The difficulty of the reaction at the same starting point is used to compare the strength of the oxidation and reducibility of the substance, and the easier the reaction with the same oxidant, the stronger the reducing agent is (indicating that it is easier to lose electrons).