How to judge that the valence state of the element has changed in the chemical redox reaction

Metals generally have only one valence state, and non-metals generally have only one negative valence state. Oxygen is generally -2 valence and, rarely, -1 valence. For example, in peroxides, oxygen is -1 valence.

The valence state is judged based on oxidation and reduction. For example, hydrogen and oxygen, hydrogen has reducibility and oxygen has oxidation, so hydrogen is positive valence and oxygen is negative, and because hydrogen is reducible and oxidation is also very strong, hydrogen and oxygen will have peroxides. You can look at other people's answers to this question ......I'm too lazy to fight.

In the first one, the chemical valence of the first k is +1, the chemical valence of o is -2, and the chemical valence of cl can be judged, and the subsequent k is +1, cl is -1, and o is 0.

Second, the previous h is +1, and o is -1.

Remember which elements will not change their valency, and the elements whose valency will change can be determined.

You can calculate it, for example, 2kclo3 = 2kcl + 3o2, the valence state of potassium chlorate is +5, and the valence of oxygen is 0, then you can know that the oxygen has dropped by 5. 2H2O2==2H2O+O2, the valence state of oxygen in hydrogen peroxide is -1, -2 in water, and 0 in O2, it can be seen that the two hydrogen atoms in hydrogen peroxide have increased by one valence and two have decreased by one price.

Oxygen is often -2 valence, potassium is positive monovalent Then the potassium in the front potassium chlorate should be positive pentavalent, and the chlorine in the potassium chloride generated later should be negative (potassium is positive monovalent), then the valency has changed!

The potassium in KCLO3 is positive 1 valence, Cl is positive 5 valence, O is negative 2 valence, and potassium in KCL is positive 1 valence, so it has not changed, Cl is negative 1 valence, from the original positive 5 valence to negative 1 valence, so it has changed, O in O2 is 0 valence, from negative 2 valence to 0 valence, so it has changed.

H2O2 in H is positive 1 valence, O is negative 1 valence, H2O in H is positive 1 valence, so it has not changed, O is negative 2 valence, there is a negative 1 valence to negative 2 valence, so it has changed, O in O2 is 0 valence, from negative 1 valence to 0 valence, so it has changed.

The change in the elevated valency of an element is called an oxidation reaction; The valency of the elements is elevatedsubstance— calledReducing agent

The valency of the element is reducedVariations— calledReduction reaction；The valency of the element is reducedsubstance— calledOxidizing agent

Oxidizing agentwithReducing agentIt's all aboutreactants。After the reaction, the oxidant is reduced; The reducing agent is oxidized

For example: carbon + oxygen = carbon dioxide.

The carbon element has increased from 0 valence to positive 4 valence, yesOxidation reactions。Carbon is a substanceReducing agent, after the reaction,is oxidized

Oxygen is reduced from 0 valence to minus 2 valence, yesReduction reaction。Oxygen is a substanceOxidizing agent, after the reaction,is restored

The increase and fall of the chemical price is to keep the Kilaheng, and the price increase must be equal to the price reduction.

Redox reaction is a chemical reaction in which the valency of an element before and after the reaction has a corresponding rise and fall change. A chemical reaction in which there is a change in the valency of an element during the reaction is called a redox reaction. This reaction can be understood as consisting of two halves, namely oxidation and reduction.

All such reactions observe conservation of charge. In redox reactions, oxidation and reduction must be carried out simultaneously in isometric amounts. The two can be likened to the relationship between yin and yang that is interdependent, transformed, ebb and flow, and oppositional to each other.

Redox reactions are also present in organic chemistry.

The reason why the valency of an element changes is that there is a transfer of electrons in a redox reaction.

The displacement reaction must be a redox reaction, and the synthesis and decomposition reaction is not necessarily a redox reaction.

Metathesis reaction is not a redox reaction.

The decomposition reaction with the formation of elemental matter must be a redox reaction, but the reaction with the participation of elemental matter is not only slippery, but it must be a redox reaction (such as graphite becoming diamond).

Summary. Hello dear, glad to answer for you! Method for judging the number of valence of elements in a redox reaction:

The valency of oxygen in sodium peroxide is minus one, and the valency of oxygen in water is minus two. The valency of oxygen in sodium hydroxide is negative 2. Assuming that the oxygen in the water changes to oxygen, that is, the valence of -2 to 0 increases, and the redox rises and falls.

How to judge the number of elements in a redox reaction that has a valence 199111, hello, I'm happy to answer for you! The method of judging the number of valence of elements in the redox reaction: the valency of oxygen in sodium peroxide is minus one, and the valency of oxygen in water is minus two.

The hand-based valency of the oxygen in sodium hydroxide is negative 2. Assuming that the oxygen in the water changes to oxygen, that is, the valence of -2 to 0 increases, and the redox rises and falls.

Proximity transformation law: When the redox reaction occurs in Youqing, the valency of the element increases or decreases to the adjacent valence state, such as s has -2, 0, +4, +6 valence states, if it is 0 valence, it increases to the nearby +4 and decreases to the nearby -2 hopping transformation law: generally the proximity law is satisfied, but if it encounters a strong oxidant or a strong reducing agent, it will be oxidized to the ** state and reduced to a low state.

When a redox reaction occurs in a substance containing the same element with different valences, the change of the valence state of the element must follow the "** spike + low price and one intermediate valence", and there will be no staggered phenomenon.

1. In the redox reaction, there are two possibilities for the valency of the element to increase, one is the loss of electrons (p-ionic compounds); Another possibility is the deviation of the electron pair (to the covalent compound).

2. Whether it is the loss of electrons or the deviation of electron pairs, it is called oxidation (or oxidation reaction), and the substance or element is a reducing agent.

In the redox reaction, the valency of the element increases, loses electrons, and is oxidized.

Oxidation Reduction Agent The valency is increased, and the electron loss is oxidized as a reducing agent.

No, as long as there is a valency of the element.

When a change occurs, a redox reaction occurs.

Because, the essence of the redox reaction is that the gain and loss of electrons or the shift of common electron pairs occurs in the reaction, that is, the transfer of electrons.

Therefore, as long as there is a change in the valency of an element in the reaction, a redox reaction has occurred, and the valency of all elements does not need to change; For example: some well-known chemical reactions.

cu+fecl2==cucl2+fe

The reaction is a redox reaction, but the valency of Cl is always -1 and does not change!

No. Just change one.

For example. Fe + HCI = FeCl2 + H2 gas.

Fe acts as a reducing agent.

HCI is an oxidizing agent, so it has changed by two.

Redox trimming.

Like this one. 10cl2

10ca(oh)2

7cacl2

ca(clo3)2

2ca(clo)2

10H2O valence liter: Cl

liter 1 * 2cl 0---5 liter 5 * 2 = 10

A total of 12 so in.

Ca(clo3)2, Ca(clo)2 before each with 1 compound valence: Cl

Drop 1*2=2

So 6 is preceded by CACL2

According to the conservation of atoms, 8, Ca(OH)2 is preceded by Cl2, and 88Cl28Ca(Oh)2 is preceded by H2O

6cacl2

ca(clo3)2

ca(clo)2

8h2o

This is the normalization and disambiguation of the valence, the situation of the return is the transformation of ** and low price to the middle valence, and the situation of disambiguation is the transformation of the middle valence state to both sides of the ** and low price, do you ask this?

When writing the redox reaction equation, follow the following rules:

In redox reactions, the conversion between adjacent valence states of elements is the easiest. If there is a reaction between different valence states of the same element, the valency of the element is only close to each other and does not cross; There is no redox reaction between adjacent valence states of the same element.

Different substances containing the same element do not undergo redox reactions if their valence states are adjacent to each other.

Proximity transformation law: when the redox reaction occurs, the valency of the element increases or decreases to the adjacent valence state, such as s has -2, 0, +4, +6 valence state, if it is 0 valence to participate in the reaction, it increases to the nearby +4, and decreases to the adjacent -2 hopping transformation law: generally the ortho law is satisfied, but if it encounters a strong oxidant or a strong reducing agent, it will be oxidized to the ** state and reduced to a low state.

When a redox reaction occurs in a substance containing the same element with different valences, the change of the valence state of the element must follow the "** + low price and intermediate valence", and there will be no staggered phenomenon.

It depends on which element has undergone valence changes in the specific reaction, such as the reaction between acid and active metal, H becomes zero-valent, HCl shows oxidation, and in the reaction of HCL to produce Cl2, Cl changes from -1 valence to zero-valent, which is HCl is reductive.

It depends on which element it is for, for example, Fe+2HCl=FeCl2+H2, then HCl is oxidizing. Another example.

f2+2hcl=2hf+cl2 (scribbled equations.。。 Then HCL is reductive.