The ratio of the amount of oxidant to reducing agent substances to be solved will not be standardize

Can it also be marked with a ...... that will not be raisedWrite out the valency of each element, just see how much the same element is different on the 2nd side of the equation, for example, Fe+2 valence on the left, Fe+3 valence on the right, then the valency of Fe will increase by 1 per 1mol Fe2+ reaction

The oxidant undergoes a reduction reaction, the valence decreases, and the reducing agent is the opposite, you follow the above mark, and then count it.

For example, if you have 5NaClO2+4HCl->5NaCl+4ClO2+2H2O, only Cl will change in valency, and the valency will be from left to right.

3 -1->-1 +4；The valence of -1 to -1 has not changed, so it is not an oxidant or a reducing agent, but at the same time, it is necessary to see that there are only 4 -1 Cl on the left, and there are 5 more than 1 on the right, so this 1 is obtained by the price reduction of Cl +3 on the left, so the 4 +3Cl on the left rises by 1 to +4Cl, which is a reducing agent; 1 +3Cl decreases by 4 to -1Cl, which is an oxidant, so the ratio of reducing agent to oxidant is 4:1

It's not normal to just learn! There are two keys to this topic: one is to grasp the two valence states before the chlorine element reaction, 5 positive trivalent chloride and 4 negative monovalent chlorine.

After the reaction, there are two valence states: 5 negative monovalent chlorides and 4 positive tetravalent chlorides. The second is to be clear about the law of price change

No crossing, no overlapping. That is: it is impossible to reduce positive trivalent chlorine to negative monovalent chlorine, and it is clear to draw a number line, in layman's terms:

The strong cannot make the weak as strong as themselves! (The selfishness of chemicals!) Just like humans).

Therefore, 4 of the 5 negative monovalent chlorines in the product are from hydrochloric acid and 1 is from positive trivalent chloride. In short, this is the "disproportionation reaction" of positive trivalent chlorine, this so-called "divergence", 1 drops to negative monovalent, 4 rises to positive tetravalent, the number of electrons transferred is 4e-, and the ratio of oxidant to reducing agent is 1:4. Complete!

If you don't know how to mark, you will learn, otherwise you don't want to learn--

The valency increases, is oxidized, and an oxidation reaction occurs, which acts as a reducing agent and generates oxidation products.

The change in the valency of an element is called an oxidation reaction. Substances with reduced valency of elements are called oxidants. The change in the valency of an element is called a reduction reaction. Both oxidizing and reducing agents refer to reactants. After the reaction, the oxidant is reduced; The reducing agent is oxidized.

How to find valence:

Valency is a property of an element that manifests itself only when the elements are compounded with each other. In the compound, the algebraic sum of positive and negative valency is equal to zero, which is the criterion for finding the valence of chemical valence. Generally speaking, there are several ways to find the following:

Chemical formula or radical formula.

1. The formula for finding the valency of element A in the bright spike AMBN compound: (the valency of element B and the number of atoms of B) the number of atoms of A.

2. Find the valency formula of the elements with unknown valency in a multivariate compound: (the algebraic sum of the valence of the elements with known valence) The number of atoms of the elements with unknown valence.

3. Judge the valency of elements (or atomic clusters) according to the number of positive and negative charges. In the radical formula, the algebraic sum of the positive and negative valence total valence numbers is equal to the positive and negative charge numbers carried by the radical.

Introduction to the Reduction Repress.

Redox anti-reverence is a chemical reaction in which the oxidation number of an element changes before and after the reaction. This reaction can be understood as consisting of two halves, namely oxidation and reduction. Essentially, there is a transfer (or shift) of electrons, but not between different elements.

Most inorganic metathesis reactions are not redox reactions, because the ions in these metathesis reactions are exchanged with each other, there is no transfer of electrons, and the oxidation number of each element does not change. <>

According to the ratio of the metrological numbers in the chemical equation (conservation using electron transfer).

Find out the oxidants and reducing agents (increased valency, reducing agents; The valency is reduced, and the oxidant and the reduction product are found, and the oxidant is reduced to the reduction product, that is, the oxidant corresponds to the reduction product; The reducing agent is oxidized into oxidation products, i.e., the reducing agent corresponds to the oxidation products.

Correctly write the chemical equation of the redox reaction, determine the oxidant and the reducing agent, and the coefficient ratio of the oxidant molecule and the reducing agent molecule is the ratio of the amount of the two substances.

For example: 2H2 + O2 = Ignition = 2H2O

Oxygen is an oxidizing agent and hydrogen is a reducing agent.

The coefficient ratio of the molecular formula of the two = the ratio of the amount of the substance of the oxidant to the reducing agent = 1:2

According to the ratio of the metrological numbers in the chemical equation (conservation using electron transfer).

First, find out the oxidant and reducing agent (elevated valency, reducing agent; The valency is reduced, and the oxidant and the reduction product are found, and the oxidant is reduced to the reduction product, that is, the oxidant corresponds to the reduction product;

The reducing agent is oxidized into oxidation products, i.e., the reducing agent corresponds to the oxidation products.

Then, according to the law of conservation of elements, find out the number of elements with increased valence (the element is the element in the reducing agent), and divide it by the number of the element in a single reducing agent molecule is the number of reducing agents participating in the reaction; In the same way, find out the number of elements with reduced valency, divide by the number of elements in a single oxidant molecule is the number of oxidants involved in the reaction; The ratio of the two is the ratio of the quantity of matter.

The ratio of the amount of the substance of the redox anti-Si Changsen The amount of the substance of the oxidant: The amount of the substance of the reducing agent.

For example: mno2 + 4HCl = mnCl2 + Cl2 + 2H2O oxidant is manganese dioxide coefficient of fast liquid 1, reducing agent is HCL, of which there are 2 valencies have changed, the ratio of the amount of substances in the redox reaction The amount of the oxidant substance: the amount of the reducing agent The amount of manganese dioxide substance:

The amount of HCl is 1:2

Another example: C O2 CO2

If both the oxidant and the reducing agent have a valency change, the ratio of the amount of substances in the redox reaction is greater than the ratio of the coefficient, as in the above reaction, the ratio of the amount of substances in the redox reaction is o2:c 1:1

An increase in valency is called a reducing agent, a decrease in valency is called an oxidant, and a decrease in valency is called a reducing agent, and an increase in valency is called an oxidant. This is mainly due to the need for oxygen for combustion.

The most common redox reaction is the combustion reaction. Combustion reactions are all involved in oxygen, oxygen is the oxidizing agent, and other combustible substances are reducing agents. Oxygen participates in the process of combustion, from 0 valence to negative bivalent, the valency decreases, and oxygen is an oxidizing agent.

Later, all those involved in the redox reaction, the valence reduction was the same as oxygen, and it was called an oxidant. Those with increased valence are called reductive repentants.

The direction and number of electron transfers are marked, and the amount of the oxidant substance that undergoes the reduction reaction and the amount of the reducing agent substance that undergoes the oxidation reaction are determined. Note: There are some oxidizing agents or reducing agents that are not involved in the redox reaction.

Example: 3Cu + 8Hno3 (dilute) ====3Cu (No3) 2 + 2 No + 4H2O

Among them, the reducing agent Cu, 3mol participates in the oxidation reaction, the oxidant Hno3, 2mol participates in the reduction reaction, and 6mol participates in the formation of salt, which only plays the role of salt formation.

So reducing agent: oxidant = 3:2

First of all, you first determine who is the reducing agent and the oxidant, and then according to the data given in the question, you can find the amount of the reducing agent and the oxidant by using the cross method, and then compare it correctly.

Observe the valence states of the individual elements of the reactants and products.

A can be judged that CU is completely used as a reducing agent, while HNO3 is partly used as an oxidant (reduced to NO), and the other part acts as an acid (copper nitrate is formed, and the valency of N remains unchanged). In each of these reactions, 3 Cu atoms are oxidized from 0 valence to +2 valence, thus losing 6 electrons; 2 Hno3 is reduced to NO (the material is conserved, 2 NO can only be changed from 2 HNO3), the valency is reduced from +5 to +2, a total of 6 electrons are obtained, and the gain and loss electrons are conserved, indicating that the analysis is correct. Hence the oxidizing agent:

Reducing agent = 2:3

B: All Cl2 is used as an oxidant, a part of NH3 is oxidized to N2 as a reducing agent, and the other part is used for salt formation to form ammonium chloride, in which each part of the reaction, 3 molecules of Cl2 are reduced to obtain 6 electrons, and 1 part of N2 (two nitrogen atoms) is oxidized, rising from -3 valence to 0 valence, a total of 6 electrons are lost, and the gain and loss of electrons are conserved. Hence the oxidizing agent:

Reducing agent = 3:1

C: H2 as a reducing agent, Fe2O3 as an oxidant, each reaction, 3 molecules of H2 are oxidized, lose 6 electrons, 1 part of Fe2O3 is reduced, of which 2 Fe from +3 valence to 0 valence, get 6 electrons, the gain and loss of electrons are conserved, so oxidant: reducing agent = 1:

3.D: All Mno2 is used as an oxidant, a part (half) of HCl is oxidized into chlorine gas as a reducing agent, and the other part is used to form MnCl2 into salts, each part of the reaction, 1 part of Mno2 is reduced, the valency of Mn is from +4 to +2, 2 electrons are obtained, half of HCl (2 parts, because 1 part of Cl2 must be derived from 2 parts of HCl) is oxidized, 2 electrons are lost, and electrons are conserved. Hence the oxidizing agent:

Reducing agent = 1:2

Note: When judging the ratio of oxidant to reductant, it should be noted that a substance may be "decorated with two corners": one part participates in the redox part and the other part participates in the non-redox part. Once found, the difficulty of the question can be greatly reduced.

Also note: The revised ratio in a is 2:3