What is the law of non crossover of high school chemical redox reactions?

To put it simply, when the same element reacts with different valences, the two valences can only be close to and close to the middle valence, and cannot be crossed, and the low valence can not rise directly above the middle valence, and the high valence cannot be lowered below the middle valence, for example, if the reaction of -2 valence and +6 valence forms 2 valence states +2 and +4, then it can only be -2 to +2, +6 to +4, and it cannot be -2 to +4 and +6 to +2

Redox reactions occur between the same elements, and the valency does not cross. For example, the redox reaction between H2S and concentrated sulfuric acid is S, SO2, then, S is from H2S, -2 rises to 0; SO2 is derived from H2SO4, and +6 is reduced to +4. No crossing, -2 to +4, +6 to 0.

Redox reactions.

, the reaction between different valence states of the same element occurs, and the valency of the element.

Only close to not crossing. Example: kclo3 6hcl kcl 3cl2 3h2o. The 5-valent chlorine in potassium chlorate is not converted to minus 1-valent chlorine in potassium chloride.

The valence states of the same element in the redox reaction are only close to each other and do not cross, for example, H2S reacts with sulfuric acid, and the sulfur in hydrogen sulfide is oxidized to 0 or 4 valence. In the same way, the sulfur in the sulfuric acid will only decrease, but it will not cross the valence state of the sulfur in the hydrogen sulfide.

That is to say, for example, the price of the +4 price S element should be reduced to 0 price first, and it cannot be directly reduced to -2 price, that is, the price cannot be overstepped.

I'm also quite struggling with this question.

H2S + H2SO4 concentrate = S = SO2 + 2H2OH2S – oxidized ---S

H2SO4 – Reduces --- SO2

There is no crossover above.

If the spike has a fork in the acre.

H2S – Oxidized --- SO2

H2SO4 -- Reduction ---s

Its essence guesses orange:

H2S -- Oxidation ---S --- Oxidation --- SO2H2SO4 -- Reduction --- SO2 --- Reduction ---S What happens after the reduction is:

S is oxidized by SO2 to SO2

SO2 is reduced by S

Apparently impossible.

That is, when ** and the low price are in the middle, they are only close to each other, not crossed.

KCLO3 + 6HCl ==KCl + 3Cl2 + 3H2O Here chlorate is +5 valence, hydrochloric acid is -1 valence.

When changing the price, there are two ways to change it.

1. The +5 valence becomes the -1 valence in the KCL, and the -1 valence in the 6 hydrochloric acid cavities is oxidized to 0 valence.

2. The +5 price becomes 0 price, one of the 6 hydrochloric acid remains unchanged, and the 5 becomes 0 price.

In the second type of tremor method, there is no cross-valency.

The situation is correct.

To put it simply, the compound price is leaning towards the middle, but the potato can't be overly leaning.

The redox reaction occurs between the same element in different valence states, and the result is that the two valence states can only be close to each other or reach the same valence state at most, and there will never be a crossover phenomenon of ** state becoming low and low price state becoming high.

For example, C CO2=2Co reactants contain C elements with 0 and +4 valence, respectively, and the product contains only one +2 valence C element, which cannot and cannot generate valence states smaller than 0 valence or larger than +4 valence. The same goes for SO2 2H2S 3S 2H2O.

I don't know if you can read it.

The valency change is low and not high.

The non-crossing law and the normalization reaction law of the oxidation return to Fengzi Huiyuan reaction are collectively called the non-crossing law of centering. It is an important law in the centering reaction.

In the learning stage of high school, the only things that cannot be balanced with electrons in the redox reaction are the disproportionation reaction and the return to the silver response, so you must be very careful when matching!

H2S + H2SO4 = S + SO2 + 2H2O, then the product S must come from H2S and SO2 must come from H2SO4

The original s were -2 and +6, followed by 0 and +4

Draw these 4 numbers on the number line, and then draw arrows from -2 0, +6 +4, and the two do not cross.

Conversely, if you draw from -2 +4, +6 0, then there will be crossing, which does not allow the same to be done, and 2Na2O2+2H2O=4NaOH+O2, O2 comes from the peroxide root which was originally -1, -2, and later -2, 0Draw arrows, if from -1 -2, -2 0 is also the same crossover, so it can only be -1 -2, -1 0

Answer: Solution: There may be a change in the valency of the elements in the compounding reaction, or there may not be a change in the valency of the elements, so the synthesis reaction with the change of the valency of the elements is a redox reaction, so the synthesis reaction and the redox reaction are cross-related

There may be a change in the valency of the elements in the decomposition reaction, or there may not be a change in the valency of the elements, so the decomposition reaction with the change of the valency of the elements is a redox reaction, so the decomposition reaction and the redox reaction are cross-related

There must be a change in the valency of the elements in the displacement reaction, so the displacement reaction must be a redox reaction, but some chemical reactions in the redox reaction are not displacement reactions, so the redox reaction contains a displacement reaction

There must be no change in the valency of the elements in the metathesis reaction, so the metathesis reaction must not be a redox reaction, so there is no intersection between the metathesis reaction and the redox reaction

Therefore, choose B Comment: This question examines the relationship between chemical reaction, decomposition reaction, displacement reaction, metathesis reaction and redox reaction, which is not very difficult, and it should be noted that there must be a change in the valency of elements in the redox reaction, but there is not necessarily oxygen to participate in the reaction

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