Do not understand redox inverse. Partial redox reactions

The so-called oxidant refers to the ability to seize electrons is stronger than the reducing agent in the reaction, which is manifested as the electron with a negative charge, and the valency changes from the ** state to the low-valence state, and the electronic structure of the outer atom tends to be more stable, and the ability to obtain electrons is weakened, which is manifested as the weakening of the oxidation ability, so the oxidation of the oxidant is stronger than the oxidation product; In the same way, after the reducing agent loses electrons, the outer electronic structure tends to be relatively stable, the ability to lose electrons is weakened, and the ability to obtain electrons is enhanced compared with the original reduced state, that is, the reduction is weakened and the oxidation is enhanced.

The redox reaction is characterized by a change in valency, but its essence is the gain or loss of electrons. The reducing agent loses electrons, the valency increases, and the oxidation product is obtained. The oxidant gets electrons, the valency decreases, and the reduction product is obtained.

The loss of electrons by a substance is reductive, and the easier it is to lose electrons, the stronger the reductiveness. The electrons obtained by the substance are oxidized, and the easier it is to get the electrons, the stronger the oxidation. Therefore, if the oxidation product is stronger than the oxidizing agent, the oxidation of the reducing product is stronger than that of the reducing agent.

Then the reaction will be reversed.

First of all, it is important to understand that oxidation does not refer to a single valence state, but to two valence states relative to a substance. It is usually said that so-and-so oxidation omits its reduced state.

In fact, oxidation is the energy difference between two valence states of the same substance, that is, the oxidation state and the reduced state, for example

The energy difference between Cu2+ Cu is the embodiment of oxidation.

In the same way, the energy difference between Zn2+ Zn is also a manifestation of oxidation.

Why does Cu2+ oxidize Zn, because the energy released by Cu2+ Cu is greater than the energy absorbed by Zn Zn2+.

That is to say, the energy difference between Cu2+ Cu and Zn2+ Zn is larger, that is, the oxidation of Cu2+ Cu is stronger than that of Zn2+ Zn, and if the reduced state is omitted, the oxidation of the oxidant Cu2+ is stronger than that of the oxidation product Zn2+.

Of course, the oxidation of the oxidant is higher than that of the oxidation product, otherwise the reaction cannot occur, if the oxidation product is more oxidizing, then who reacts with the reducing agent?

The same is true for reducing agents that are more reducible than reducing products.

In fact, this is a general law, only those with strong oxidation can produce relatively weak oxidizing substances.

Think of it this way: all chemical changes in matter follow one main rule, which is to move from instability to stability. You can also understand that there is a change from strong reduction to weak reduction or even no reduction. (Strong oxidation and strong reduction are understood as two extremes, with no reduction and no oxidation at the center of them.)

Both extremes are unstable and tend to be central. ）

Then it is the so-called strong to control the weak. Thus, in general, we will less often see correspondingly weak matter and strong matter (in the case of the same nature). (Of course, if the conditions are right, it is also possible to turn stable into unstable).

Let's start with the simplest understanding of hydrogen reduction copper oxide, hydrogen as a reducing agent, copper oxide as a reducing agent, copper oxide as an oxidant, hydrogen oxide, so the oxidation of copper oxide is greater than the oxidation of water of the oxidation product of hydrogen oxidation.

It refers to the fact that only some of the substances involved in redox elements have valencies.

The alteration that is not discussed in a section is an element within a compound. Cu+2H2SO4=CuSO4+SO2+2H2O, sulfuric acid is partially oxidized.

Redox reactions are chemical reactions.

Before and after, there is a class of reactions in which the oxidation number of the element changes. The essence of a redox reaction is the gain or loss of electrons or the shift of shared electron pairs. Redox reaction is one of the three basic reactions in chemical reactions.

Combustion, respiration, photosynthesis, chemical batteries in production and life, metal smelting, rocket launches, etc. are all closely related to redox reactions in nature. The study of redox reactions is of great significance to the progress of mankind.

1. The essence of redox reaction.

The transfer of electrons took place. (i.e., in ionic compounds, it is the gain and loss of electrons, and in covalent compounds, it is the shift of shared electron pairs.) A reaction in which electrons are transferred between reactants, also known as a redox reaction).

Redox reaction**.

The reaction valence of oxygen is increased, and it is called oxidation reaction, and there is an elemental chemical reaction. The reaction of oxygen loss of substances is called reduction reaction There is a reaction in which the valence of elements is reduced, and the reaction in which oxygen is both gained and oxygen is lost, which is called redox reaction.

Second, there is no knowledge expansion.

1.Distinguishing formula: Rise and loss of oxidation reducing agent.

i.e. e. elevated valency loss of electrons oxidation reaction reducing agent) <>

Formula**. 2.Redox reaction example – hydrogen and chlorine.

The total reaction formula of the chemical reaction of hydrogen and chlorine is as follows:

h2 + cl2 =2hcl

Oxidation reaction: H2 - 2E 2H+

Reduction reaction: Cl2 + 2E-2Cl

The total number of units is 0 and the number of imitations. In the first and a half reactions, hydrogen is oxidized from 0 valence to +1 valence; At the same time, in the second half reaction, the element chlorine is reduced from 0 valence to -1 valence. (In this paragraph, "valence" refers to the number of oxidations).

The oxidation reaction is to be oxidized. In the oxidation reaction, the reducing regressor is oxidized and the oxidizing agent is reduced.

Oxidation reaction in the narrow sense refers to the combination of substances and oxidation; The reduction reaction refers to the sacrificing effect in which a substance loses oxygen. Broadly speaking, the oxidation value increases during oxidation; The oxidation value decreases when reduced. When organic matter reacts, the effect of introducing organic matter into oxygen or removing hydrogen is called oxidation; The action of introducing hydrogen or losing oxygen is called reduction.

The slow reaction between the substance and the oxygen is called slow oxidation, such as metal rust, biological respiration, etc. Intense luminous oxidation is called combustion.

For strong exothermic reactions, the reaction temperature must be strictly controlled to prevent safety accidents;

The reaction pathways are diverse, the by-products are many, and the separation is difficult; It is prone to deep oxidation and requires a catalyst with excellent selectivity.

1. Magnesium burns in the air: 2mg+O2=2MGO white signal flare.

Phenomenon: (1) Radiates dazzling white light (2) Releases heat (3) Generates white powder.

2. Iron burns in oxygen: 3Fe+2O=2Fe3O4 Phenomenon: (1) Burning violently, sparks radiating (2) Releasing heat (3) Generating a black solid.

Note: Put a small amount of water or fine sand at the bottom of the bottle to prevent the generated solid matter from splashing down and bursting the bottom of the bottle.

3. Copper is heated in the air: 2Cu+O2=2Cuo Phenomenon: The copper wire turns black and is used to test whether it contains oxygen.

4. Aluminum combustion in the air: 4AL+3O2=2AL2O3 Phenomenon: emitting dazzling white light, exothermic, and white solid generation.

5. Combustion in the air of hydrogen: 2H2 + O2 = 2H2O high-energy fuel.

Phenomenon: (1) Light blue flame is produced (2) Heat is released (3) Water mist appears on the inner wall of the beaker.