Please tell me about the properties or laws of the oxidative reduction of transition elements, thank

Excessive elements If it's not a competition, it's enough to learn about the 10 elements of the fourth cycle, and grasp some of the properties of fe, cu, and zn.

Fe3+ oxidation.

Stronger, Cu2+ has oxidizing properties, Zn, Fe, Cu reducibility.

Gradually weakened, if it is a competition, based on the 10 species of the first transition system, the vertical analogy of the elements of the same family of elements in the general ** state of the transition metal compound has strong oxidation, such as CRO42-, CR2O72-, KMNO4, FeO42-, CO3+ Ni3+, Cu2+

The lower valence states are reductive, Fe2+, Cu2O, Ni2+,

The oxidative and reducing properties of transition elements are uncertain.

It is a metal on the basis of reducibility (except C).

Non-oxidizing.

1. Oxidation vs reduction.

2. Oxidation: the ability of a substance to obtain electrons. Reducibility: The ability of a substance to lose electrons.

3. The strength of the oxidation and purification reduction of a substance depends on the difficulty of gaining and losing electrons, and has nothing to do with the number of electrons gained and lost.

4. The method for judging the strength of oxidation and bridging reducibility, the order of element activity, the order of metal activity, according to the order of metal activity, the reduction of elemental matter is getting weaker and weaker, and the oxygen noise of the corresponding cation is becoming stronger and stronger.

5. Order of non-metal activity: According to the order of non-metal activity, the oxidation of the element is getting weaker and weaker, while the reduction of the corresponding anion is gradually increasing. According to the position of the elements in the periodic table.

6. Elements of the same period: the reducibility of the element is gradually weakened, and the oxidation is gradually enhanced. The oxidation of the corresponding cation gradually increases, while the reduction of the anion gradually decreases.

7. Elements of the same main group: the oxidation of the element is gradually weakened, and the reduction of the corresponding anion is gradually enhanced.

The outermost S electrons and the second outer D electrons of the transition element can participate in bonding, so the transition element often has multiple oxidation states. Generally, it can be increased from + to the same oxidation state as the group number (there is no + oxidation state for other elements in group B except for Ru and OS).

In the same period, from left to right, the oxidation state first gradually increases and then decreases.

With the increase of the number of electrons in the 3d orbital, the oxidation state gradually increased. When the number of electrons in the 3d orbital reaches 5 or more, the 3d orbital gradually tends to be stable, and the high oxidation state gradually becomes unstable (showing strong oxidation), and then the oxidation state gradually decreases.

The oxidation states of the three transition elements change from left to right. The difference is only the first.

The highest oxidation states of the second and third transition elements are stable, while the low oxidation state compounds are uncommon.

From top to bottom in the same family, the high oxidation state tends to be relatively stable--- and the elements of the main group are different.

It can't be compared to the oxidation or reduction of oxidation products and reduction products!

Generally speaking: in redox reactions, we only compare the oxidation of the oxidant and the oxidation product, or the reducibility of the reducing agent and the reduction product.

For example: Fe+Cu2+=Fe2+ +Cu, ferrous ions are oxidation products, which are oxidizing and weaker than copper ions, but the reduction product Cu has no oxidation, so it cannot be oxidized with Fe2+ (of course, if you look at the non-oxidation as zero, then the oxidation product is stronger than the reduction product).

Another example: Zn+2Fe3+ = Zn2+ +2Fe2+, Zn2+ is an oxidation product, but it has weaker oxidation than Fe2+ (Zn is ranked after Fe in the order of activity).

Can't compare.

For example: Cl2+H2O HCl+HCl, HCl is a reducing product, HCl is an oxidation product, and HCl is obviously strongly oxidized, so oxidizing HCl, that is, oxidizing HCl, is a strong oxidation product, and reducing HCl is strong.

For example, in H2S+H2SO4 S +2H2O+SO2, S is the oxidation product, SO2 is the reduction product, and the oxidation of S element is weaker than that of SO2, so the oxidizing SO2, that is, the reduction product is strong.

Usually, it is only the oxidation (reducing product) and the oxide (reducing product) that are compared with the oxidation (reducibility), that is, the oxidation (reducibility) of the oxide (reducer) is greater than that of the oxidation product (reducing product), and the oxidation and reduction of the oxidation and reduction products are not comparable at all ......

Not comparable for reasons upstairs.

Judging by the valence state of the element:

If the element in the substance has the most **, the element is only oxidized (such as metal cations: Cu2+, Ag+, Na+, Fe3+ and Mn element in KMno4, etc.); When an element in a substance has its lowest valence, the element has only reducing properties (such as metal elements: Na, Mg, Al, Zn, Fe, non-metal anions S2-, I

Cl-, Br- and their compounds NH3 in N, etc.); When an element in a substance has an intermediate valence, the element is both oxidizing and reducing. Generally, for the same element, the higher the valence state, the stronger its oxidation; The lower the valence state, the more reducible it is (the opposite of the positive valence halogen).

It can be judged from the following common important oxidants and reducing agents to find the valence. 

Oxidant active non-metallic elements: X2, O2, S

**Metal ions: Fe3+, Sn4+

Inactive metal ions: Cu2+, Ag+ Others: Ag(NH3)2+, new Cu(OH)2

Oxygenated compounds: NO2, N2O5, MNO2, Na2O2, H2O2, HCO,

HNO3, concentrated H2SO4, Naclo, Ca(clo)2, KCLO3,

kmno4, aqua regia.

Reductant active metal elements: Na, Mg, Al, Zn, Fe

Certain non-metallic elements: C, H2, S

Low-valent metal ions: Fe2+, Sn2+

Anions of non-metals and their compounds:

s2-、h2s、i

hi、nh3、cl-、hcl、br-、hbr

Low-valent oxygenates:

co、so2、h2so3、na2so3、na2s2o3、nano2、

H2C2O4, organic matter containing -CHO: aldehyde, formic acid, formate, a certain ester of formate, glucose, maltose, etc.

It can be used as both an oxidant and a reducing agent: S, SO32-, HSO3-, H2SO3, SO2, NO2-, Fe2+, etc., and organic substances containing -CHO are expected to be adopted.

Some substances can be used as both oxidants and reducing agents, such as Na2O2, H2O2, S, Fe2+, SO2, etc., but they are mainly based on one property: Na2O2, H2O2, S are mainly used as oxidants, and Fe2+ and SO2 are mainly used as reducing agents.

Most. For example, if a substance can react with sodium metal to form a monovalent sodium compound, then the sodium is oxidized, and the substance is oxidizing.

At the same time, the substance can react with F to generate monovalent fluoride, then the fluorine is reduced, and the substance has reducibility.

Obviously, a lot of substances can react like this.

Because the oxidation of the oxidation product cannot be greater than that of the oxidant, the reducing product cannot be greater than the reducing agent.

Valence state centering law: when redox reactions occur between different valence states of the same element, the change of valence states is "only close, not crossing".

For example: KCLO3+6HCl=3Cl2+KCL+3H2O.

The valence is high or, and the negative monovalent element cannot reduce the 3rd valence to the 1st valence and itself to the positive 5th valence. That is to say, the original high, after the reaction, the valency is still relatively high, and the low is still low. (Exceptional cases are equal).

For example: KCLO3+6HCl=3Cl2+KCL+3H2O.

Valence is the property of an element that manifests itself when one atom is atomized with other elements.

In general, the valence of valence is equal to the number of electrons gained and lost by each atom during compounding, that is, the number of electrons gained and lost when the element can achieve a stable structure, which is often determined by the electronic configuration of the element, mainly the outermost electron configuration, and of course, it may also involve the substable structure composed of sublayers that can be achieved by the subouter shell.

Oxidation and reducibility refer to matter, and refer to the ability of a substance to gain electrons and the ability of a substance to lose electrons, respectively. If we want to talk about this ability of elements to gain and lose electrons, we should refer to the metallic and non-metallic properties of elements. In fact, the oxidation of matter is unified with the non-metallic nature of the element, the reduction of the substance and the metallicity of the element.

As for judging oxidation or reduction, it can be judged according to the redox reaction. There is such a couplet about the redox reaction, you can remember: the oxygen is lost when the oxygen is lost, the oxygen is still reduced, and the oxygen is returned; It can be interpreted as:

The valency increases, loses electrons, is oxidized, and oxidation reactions occur, and oxidation products are obtained, which are used as reducing agents, and reducing agents have reducing properties. The valency decreases, electrons are obtained, they are reduced, a reduction reaction occurs, a reduction product is obtained, and an oxidant is made, and the oxidant is oxidizing. (1) According to the chemical equation (1) Oxidant (oxidation) + reducing agent (reducibility) = = reducing product + oxidation product Oxidation:

Oxidant》Oxidation product Reducibility: Reducing agent》Reducing product (2) According to the oxidant in the same reaction, the reducing agent can be judged Oxidation: Oxidant》Reducing agent Reducibility:

Reducing agent》Oxidant (2) According to the reaction conditions, when different oxidants react with the same reducing agent, if the valence state of the oxidation products is the same, it can be judged according to the difficulty of the reaction conditions. The easier the reaction, the more oxidizing the agent will be oxidized. Such as:

16HCl (concentrated) + 2kmNO4==2KCl+2MnCl2 + 8H2O + 5Cl2 (gas) 4HCl (concentrated) + MNO2=== heated) MNC2 + 2H2O + Cl2 (gas) 4HCl (concentrated) + O2== (heating, CuCl2 catalyst) 2H2O + 2Cl2 (gas) Oxidation: KMnO4> mNO2 >O2 (3) Judge according to the valence state of the oxidation product When the reducing agent containing valence elements acts on different oxidants under similar conditions, the oxidation of the oxidant can be judged according to the valence state of the oxidation product. Such as:

2Fe+3Cl2==(ignition)2FeCl3 Fe+S==(Heating)Fes Oxidation: Cl2>s (4) Comparison according to the order of material activity (1) For metal reducing agents, the reducing strength of metal elements is generally consistent with the order of metal activity. 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 is generally reversed from the order of metal activity. k+

1.The effect of concentration on the oxidation and reduction of substances.

Generally speaking, the higher the concentration of the solution, the stronger the oxidation and reduction of the solute. In the chlorine gas reaction, if the concentration of hydrochloric acid is too low, the reaction can not be carried out, and then when the concentration is large, the redox reaction occurs, and the metathesis reaction occurs when the concentration is smallIn addition, the different concentrations of oxidants and reducing agents will make the redox products different, such as dilute nitric acid reduction products are generally NO gas, and concentrated nitric acid reduction products are.

2.The effect of temperature on the oxidation and reduction of substances.

Generally speaking, the higher the temperature of the substance, the stronger the oxidation or reduction, such as carbon increases with the increase of temperature, and almost all metal oxides can be reduced.

3.The acidity and alkalinity of the solution have an effect on oxidation and reduction.

Acidic conditions can enhance the oxidizing ability of the oxidant and facilitate the centering reaction. Under neutral and alkaline conditions, the oxidant ability will be weakened and the disproportionation reaction will be favored. For example, the oxidation capacity of the acidified solution is much greater than that of the alkaline solution, and its reduction products are also different.

It is reduced to nearly colorless in acidic media; neutral medium, is reduced to. Another example: when it is introduced into water or alkali solution, disproportionation reaction occurs, and with can be obtained by centering reaction.

4.The effect of catalyst on the oxidation and reduction of substances.

The use of catalyst or not affects the reaction rate in the first place. In addition, the redox products will be different when using different catalysts, such as:

5.**The oxidation of state elements is not necessarily strong.

The most ** is only oxidation, but the strength of oxidation is also affected by the stability of the atomic cluster where the element is located, the more stable the structure of the atomic group, the weaker the oxidation of the substance, and vice versa. Such as:Due to its stable structure, it hardly exhibits oxidation; However, due to its unstable structure, it exhibits strong oxidation and is an oxidizing acid.

Another example is the oxidation of chlorine oxygenated acid:

6.Although the intermediate valence of the element can show both oxidation and reduction, it can still be a strong oxidizing agent.

Although the intermediate valence of the element can both gain electrons and lose electrons, the ability to obtain electrons can still be very strong, such as (or) the intermediate valence of oxygen elements, which can show both oxygen megamacronization and reduction in the reaction, but because oxygen atoms can be released in the reaction, it is still a strong oxidant.

7.The oxidation and reduction of substances are affected by the state of matter.

Generally speaking, the oxidation and reduction of solid-liquid state is greater than that of gaseous state. In addition, the oxidation and reduction in the solution are different from those of pure substances, such as the reduction in aqueous solution, while the reduction of gaseous metals is, oxidation: greater than in solution.

8.The element is not necessarily consistent with its elemental redox properties.

For example, because there are three covalent bonds in the structure, the bond energy is large, and the chemical reaction needs to break the three covalent bonds first and consume a large amount of energy, so it is inactive at room temperature. N elements, on the other hand, exhibit active nonmetallicity because of their small atomic radius and large number of electrons in the outermost shell.

9.The redox property of a substance is affected by its structure.

For example, Cus can be oxidized by nitrate Gaoshu acid, but it cannot, because the crystal structure is not easy to be the same as CuS, and the structure is relatively compact, so it is not easy to be oxidized.