How to distinguish between bleaching and redox?

Bleaching"Not a chemical term. SO2 makes magenta.

The fading is actually a complex of the SO2 molecule and the magenta, causing the magenta to lose its color, which turns back to its original color once heated.

And chlorine. "Bleaching" with bleaching powder is the oxidation of clo (hypochlorite) formed after contact with water.

caused, it cannot be restored.

SO2 is reducible and can react with oxidizing groups, and has very weak oxidation.

Therefore, when answering "bleaching", just remember the magenta.

Bleaching refers to the property of a substance that causes a colored substance to fade, and bleaching can be a physical change (activated carbon adsorption) or a chemical change (SO2, Cl2, etc.).

Oxidation refers to the property of a substance to gain electrons (reduced valency).

So the bleaching property of a substance is not necessarily because it is oxidizing; Oxidizing substances are also not fully used for bleaching.

The use of sulfur dioxide to fade colored substances, and the use of magenta solution to fade bleaching; Fade acidic potassium permanganate solution, bromine water is the use of reducibility!

The team will answer your questions, thank you!

There are three types of bleaching at the secondary level:

1. Cl2 water, HCl, H2O2, Na2O2, etc.

It is because of their strong oxidizing properties, which oxidize organic pigments into other colorless substances and fade.

It is a chemical property.

2. SO2 is because it can be combined with organic chromogen to form a colorless substance, which is not very stable, and after a long time, it will decompose, and after releasing SO2, it will return to its original color.

It is also a chemical property.

3. Activated carbon.

Because of its adsorption, it adsorbs colored substances and causes the color to fade.

It is of a physical nature.

Redox is related to the state of the valency of the constituent elements, if the valency is in the highest position, there is only oxidation, if the valency is in the lowest position, then there is only reduction, if the valence is in the middle position, it can rise or fall, both oxidation and reduction.

S in SO2 is 4-valent, in the middle valence state of S, so it has both oxidation and reduction, but when it reacts with potassium permanganate, it shows reduction, is oxidized, and the valency continues to increase, forming H2SO4.

The difference between bleaching and oxidation is: different rules and different types involved.

Bleaching law, sulfur dioxide can make many colored substances fade, but its fading principle is different: reducing fading: sulfur dioxide can make bromine water, acidic potassium permanganate, solution fade, using the reducing property of sulfur dioxide. Bleaching fades, acidic fades.

The principle of strong oxidizing bleaching (permanent bleaching): the "chromophore" inside the organic chromophore is destroyed and oxidized into a colorless substance. Chemically bleached.

Principle: Addition or synthesis of colorless substances with colored organic compounds, and the color disappears after the decomposition of the colorless new substance. Principle of physical adsorption bleaching:

Absorbs organic pigments and fades. Common such substances are: activated carbon, colloids.

The law of oxidation: the law of reaction relationship, the oxidant gets electrons, the valency decreases, and it is reduced to a reduction product; The reducing agent loses electrons, and the valency is increased and oxidized to oxidation products. The law of knowledge clue relationship loses electrons, the valency increases, and the reducing agent.

Common oxidants and their reduction products.

The objects of bleaching are usually fiber materials, textiles, etc., while the objects of oxidation are usually first-class substances and active non-metallic elements.

Oxidation: Refers to the ability of a substance to gain electrons. Substances in the ** state and active non-metallic elements (such as: fluorine, chlorine, oxygen, etc.) are generally oxidizing.

Bleaching: The process of adding water and chemicals (oxidants or reducing agents) to remove the color contained in fiber materials, textiles, etc., and make them white.

1) Substances in the ** state are generally oxidizing, such as: some non-metallic elements: O2, Cl2; Some metal cations: Fe3+, MnO4-(Mn7+), etc.

2) Substances in the low-valence state are generally reducible (such as: some metal elements: Cu, AG (metal elements only have reduction), some non-metal anions: br-, i-, etc.

3) Substances in the intermediate valence state generally have both reducing and oxidizing properties (e.g., tetravalent sulfur).

Strong oxidizing bleaching: The principle oxidizes colored substances into colorless substances. Strong oxidizing bleaching agents such as:

HCl, CA(CLO)2 (active ingredient of bleaching powder), Naclo, H2O2, Na2O2,: strong oxidizing properties, often used for tap water disinfection.

Chlorine gas is introduced into water) Ca(clo)2: Ca(clo)2 and CO2 and water produce HClo and are bleaching, which is often used for bleaching clothes and fabrics. h2o2：

H2O2 has strong oxidizing properties, and 3% hydrogen peroxide is commonly used in medical disinfection. Na2O2: Na2O2 has strong oxidizing properties and is often used for bleaching fabrics, silk, wheat straw, etc.

O3: O3 is extremely bleaching and is often used for disinfection.

The above content reference: Encyclopedia - Bleaching.

The above content reference: Encyclopedia - Oxidation.

Bleaching: It reacts with H2O to form H2SO3, and H2SO3 combines with colored substances to form an unstable colorless stool stuffiness. It is not a redox reaction. Jujube celery bend.

Reducibility: Sulfur dioxide can undergo redox reaction with some inorganic substances, such as bromine water and potassium permanganate, and the valency of sulfur element increases.

Bleaching is reversible and can be restored; The valency remains unchanged. Reductivity is irreversible, and the valency increases.

Bleaching is a conventional saying that has been handed down since the establishment of chemistry, and bleaching is not a strict concept, and there is generally no need to worry about whether it belongs to bleaching. There is often one more kind of bleaching in the industry, and there is one more principle of bleaching. However, if the industrial bleaching reaction is put in the laboratory as an ordinary experiment, it may not be able to continue to be called bleaching.

For example, if food browning produces Fe3+, this type of food can be bleached by using the reducing property of SO2, where the reducing property of SO2 is bleaching; However, in the laboratory, FeCl3 and SO2 are reacted, and Fe3+ is reduced to Fe2+ by SO2.

Another example: SO2 fades KMNO4. Middle School Chemistry has always insisted on:

It's not bleaching, it's reductive。This statement does not make sense,If it's reductive, can't it be bleaching at the same time? Can I say that HCO fades magenta, which is the strong oxidizing property of HCL, and then deny that it is its bleaching properties?

Studying chemistry has helped us understand the principle of fading, and it really doesn't matter whether the genus is bleached or not.

It is indeed its reductiveness.

Oxidation. It refers to the valency of a substance that can contain Yuanhui Bisu contained in other substances.

Elevation, in other words, is the property of the source of electrons.

Some highly oxidizing substances can oxidize other colored substances to be colorless.

However, in addition to the use of oxidation, bleaching can also be other, such as activated carbon adsorption of colored group substances, which is also a kind of bleaching.

Reducibility is relative to oxidation, which can reduce other substances, that is, it has reductivity (the ability of a substance to burn and lose electrons, and the valency of the elements in the substance can be increased.

Oxidation refers to the ability of a substance to gain electrons. Substances in the ** state are generally oxidizing.

Bleaching is the property that can make the color of the surface of the substance fade to white, most of the bleaching reflects the oxidation of the substance, but some of the bleaching is not allowed to be stared at, for example, the bleaching of sulfur dioxide is caused by the formation of new composite segments and substances.