Why can t redox coexist in large quantities?

Conditions for ion coexistence: acid-base neutralization does not occur; No gas and precipitation are generated; No redox reaction occurs.

i.e. valence. lifting), remember which ones are oxidizing.

Ions and reducing ions hypochlorite can not coexist with divalent iron ions, pay attention to the acidity and alkalinity of the solution, hydrogen ions and nitrate have strong oxidation when coexisting, and can not coexist with positive divalent iron ions, chloride ions.

Hypochlorite ions'It can coexist in an alkaline environment, but not in an acidic environment.

The so-called ion coexistence is essentially to see whether there is a reaction between ions. If the reaction occurs in solution, it cannot coexist. None of the following can coexist:

1 Ions that can react with each other to form insoluble substances cannot coexist. For example, Ba2+ cannot coexist with CO32-, SO42-, SO32-, etc. The solubility table can be referred to for analysis.

2 Ions cannot coexist if they can react with each other to form gases. For example, H+ cannot coexist with HCO3-, CO32-, S2-, etc.

3 Ions can combine with each other to form water, NH3·H2O

and other weak electrolytes, they cannot coexist. For example, OH- ions cannot coexist with H+, NH4+, HCO3-, etc.

4. Redox reactions can occur between ions, but they cannot coexist. Such as FE

2+, I, and S2 cannot coexist with NO3- in an acidic environment.

The coexistence of Fe3+ and S2- is a redox reaction, because the iron ions have a certain oxidation, and the sulfur ions are in the lowest valence state, which has a certain reduction, and the two react to form elemental sulfur precipitates and ferrous ions. If you are answering the question, be careful, it is possible that the sulfur ions are excessive, and the ferrous ions will continue to react with the sulfur ions to form Fes precipitates.

Strong oxidizing: mno4-, clo-, fe3+, mno4(2-), cro4- (dichromate ion), etc.

Strong reducibility: Ag+, Fe2+, S2-, Cu2+, I-, etc., which will react with the above binding (except for the two iron-bound ones).

Non-reactive ions can coexist, including non-gas formation, precipitation, color change, and so on.

An oxidation-reduction reaction (also known as redox reaction) is a chemical reaction.

Before and after, there is a class of reactions in which the oxidation number of the element changes. Redox reactions.

The essence is the gain or loss of electrons or the shift of shared electron pairs. The redox reaction is one of the three basic reactions in chemical reactions (the other two are the (Lewis) acid-base reaction and the free radical reaction). Combustion, respiration in nature.

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

Whether a chemical reaction is a redox reaction can be judged according to whether the reaction has an increase in the oxidation number, or whether there is electron gain and loss and transfer. If there is a conflict between the two, the former will prevail, for example, although the reaction has electron pair bias and collision, but because the IUPAC regulations have an elemental oxidation number of 0, this reaction is not a redox reaction.

In redox reactions, the following general rules exist.

Law of strength: oxidation.

Oxidant》Oxidation products; Reducibility: Reducing agent.

Reduction products. Valence law: the element is in the most advanced state and only has oxidation; The element is in the lowest valence state and is only reductive; It is in the intermediate valence state, which is both oxidizing and reducing.

Transformation law: the normalization reaction occurs between different valence states of the same element.

, the oxidation number of the element is only close but not crossed, and at most reaches the same valence state.

Priority law: For the same oxidant, when there are multiple reducing agents, it usually reacts with the most reducing agent first.

Conservation law: The number of electrons gained by the oxidizing agent is equal to the number of electrons lost by the reducing agent.

1. It has a strong strength.

Reductiveness. Target.

Ion. Can not be with a stronger.

Oxidation. of ions coexist in large quantities. For example, i- and Fe3+ cannot coexist in large quantities because 2i- 2Fe3+ = i2 2Fe2+.

2. In. Acidity. Or. Alkaline.

Target. Medium. Because of the hair and pretend.

Redox reactions.

And not coexist in large numbers. Such as no3- and i- in. Neuter. Or.

Alkaline solution. can coexist, but cannot coexist in the presence of a large number of hail-based H+; SO32- and S2- can also coexist under alkaline conditions, but cannot exist under acidic conditions due to the occurrence of 2S2- hall disturbance SO32- 6H+ 3S 3H2O reaction.

Conditions for ion coexistence: acid-base neutralization does not occur; No gas and precipitation are generated; No redox reaction occurs (i.e., valency rises and falls), remember which are oxidizing ions and reducing ions hypochlorite, can not coexist with divalent iron ions, pay attention to the acidity and alkalinity of the solution, hydrogen ions and nitrate coexist with strong oxidation, can not coexist with positive divalent iron ions, chloride ions hypochlorite ions'It can coexist in an alkaline environment, but not in an acidic environment.

The so-called ion coexistence is essentially to see whether there is a reaction between ions. If the reaction occurs in solution, it cannot coexist. None of the following can coexist:

1 Ions that can react with each other to form insoluble substances cannot coexist. For example, Ba2+ cannot coexist with CO32-, SO42-, SO32-, etc. The solubility table can be referred to for analysis.

2 Ions cannot coexist if they can react with each other to form gases. For example, H+ cannot coexist with HCO3-, CO32-, S2-, etc.

3 Ions that can combine with each other to form weak electrolytes such as water and NH3·H2O cannot coexist. For example, OH- ions cannot coexist with H+, NH4+, HCO3-, etc.

4. Redox reactions can occur between ions, but they cannot coexist. For example, Fe2+, I, and S2 cannot coexist with NO3- in an acidic environment.

The coexistence of Fe3+ and S2- is a redox reaction, because the iron ions have a certain oxidation, and the sulfide ions are in the most voltient low-price state, which has a certain reductionability, and the reaction between the two forms elemental sulfur precipitation and ferrous ions. If you are answering the question, be careful, it is possible that the sulfur ions are excessive, and the ferrous ions will continue to react with the sulfur ions to form Fes precipitates.

Strong oxidizing: mno4-, clo-, fe3+, mno4(2-), cro4- (dichromate ion), etc.

Strong reducibility: Ag+, Fe2+, S2-, Cu2+, I-, etc., which will react with the above binding (except for the two iron-bound ones).

Whether it is a redox reaction depends on whether there is a change in valency in the reaction.

For example, Fe3+ becomes Fe2+