Summary of common bleaching substances, what are the bleaching substances

Chlorine water is a commonly used bleaching substance in high school chemistry.

Na2O2, O3, H2O2, Naclo, Ca(ClO)2, SO2, activated carbon.

Wait. 1. Analysis of the principle of bleaching.

a) Chlorine water, Na2O2, O3, H2O2, Naclo (the active ingredient of bleaching solution), and Ca(clo)2 (the active ingredient of bleaching powder) are bleaching because they have strong oxidizing properties.

It can oxidize colored substances (such as acid-base indicators, magenta and other organic substances) into colorless substances. Once oxidized, they cannot return to their original color, so their bleaching effect is permanent. Note: (Dry chlorine.)

Non-bleaching, Naclo, Ca(clo)2 bleaching due to the formation of H Clo in air or acidic solution).

2) SO2 has a bleaching effect because it is dissolved in water to form H2SO3, H2SO3 can combine with colored organic compounds (such as magenta) to form unstable colorless compounds, and colorless compounds can restore their original color under certain conditions (such as heating), and this bleaching is temporary bleaching. The bleaching effect of SO2 has special characteristics. (Note:.)

SO2 does not bleach acid-base indicators, but it can redden litmus solution because SO2 dissolves in water to form sulfurous acid).

3) Activated carbon adsorbs colored substances and plays a bleaching role, which is a physical change.

Na2O2, H2O2, O3, HClL or (Cl2), concentrated sulfuric acid, concentrated nitric acid, SO2, activated carbon, charcoal, and silica gel all have bleaching properties, but the bleaching principle and bleaching effect are different. Na2O2, H2O2, O3, HCl, concentrated sulfuric acid, concentrated nitric acid all have strong oxidation, their bleaching principle: the use of Na2O2, H2O2, O3, HCO, concentrated sulfuric acid, concentrated nitric acid strong oxidation of organic pigments into colorless substances, fade can not restore the original color.

The bleaching of these bleaching substances is called permanent bleaching. The bleaching principle of SO2: SO2 is directly combined with organic pigments to form an unstable colorless substance, which returns to its original color under certain conditions after fading.

Bleaching of SO2 is temporary. The bleaching principle of activated carbon, charcoal, and silica gel: it uses their porous adsorption bleaching, and it also returns to its original color after heating.

Bleaching of activated carbon, charcoal, and silica gel is physical bleaching. Bleaching of activated charcoal, charcoal, and silica gel is also temporary.

Substances with bleaching properties can be divided into two main categories from a physical and chemical point of view: chemical bleaching and physical bleaching. Chemical bleaching can be further divided into: oxidative bleaching and chemical bleaching.

CL2 and SO2 are both gases and have bleaching properties, but the bleaching principle and bleaching effect are different. Bleaching principle of Cl2: Cl2 dissolved in water to produce HClo has strong oxidizing properties, oxidizing colored substances into colorless substances, and cannot return to their original color after fading.

The bleaching principle of SO2: SO2 is directly combined with colored substances to form an unstable colorless substance, which returns to its original color under certain conditions after fading.

Chemical action: Hypochlorite HCO, ozone O3, concentrated nitric acid HNO3, peroxide (Na2O2, H2O2, etc.) ......All of the above are oxidation), sulfur dioxide SO2 (a colorless unstable substance formed by chemical reaction) ......

Physical effect: toner (charcoal, activated carbon......c, molecular sieves (both adsorption) ......Change the temperature and cover the surface with a white substance with low transparency.

Generally, substances with strong oxidizing properties are acceptable.

It is generally highly oxidizing.

There are activated carbon, chlorine water, sodium peroxide, ozone, hydrogen peroxide, sulfur dioxide, hypochlorous acid, sodium hypochloride, calcium hypochloride (the active ingredient of bleaching powder), etc.

Adsorption bleaching: activated carbon and aluminum hydroxide colloids adsorb colored substances and play a bleaching role, which is a physical change.

Strong oxidizing bleaching: such as hydrogen peroxide, sulfur dioxide, hypochlorous acid, ozone, etc.

Bleaching of chemical reactions: such as sulfur dioxide (but not bleaching acid-base indicators).

Bleaching chemically refers to the transformation of a colored object into white after a series of chemical reactions. It can oxidize or reduce the chromogenic groups of organic colored substances, but the basic substances of organic colored substances are not destroyed, and this change is called bleaching.

The main methods of bleaching are oxidation and reduction. The oxidation method uses an oxidant with strong oxidizing properties to oxidize colored molecules to generate colorless molecules. This method is harmful to fabric fibers, so it is not suitable for fabrics such as silk and wool.

The reduction method reduces colored molecules through a reducing agent with strong reducing properties to generate colorless molecules. This method has little damage to the fabric fiber, but the product can be restored to a colored state under oxidation, so it is only suitable for some fabrics such as silk and wool.

Chemical action: hypochlorous acid HCO, ozone O3, concentrated nitric acid HNO3, peroxide Na2O2, H2O2, etc., sulfur dioxide SO2.

Physical action: toner C, molecular sieve are adsorption.

Bleaching usually refers to the result of the two reacting to the same time as the reaction of the original and returning the colored substance to colorless or white. Generally, bleaching mostly refers to organic solvents or salts with peroxidizing ability, which can directly produce a reductive reverse reaction on polysaccharides or sulfonate dyes containing pigment groups, digging groups or hydrogenation.

Common substances with bleaching properties are:

1. Sulfur dioxide. Sulfur dioxide can be used with colored substances to form unstable molded colorless substances, so it has bleaching properties, and after heating or placement, the unstable colorless substances will decompose and the color will appear again. Sulfur dioxide is best known for its ability to make magenta solutions colorless.

2. Chlorine. Chlorine is toxic and has strong oxidizing properties, and can be used for bleaching pies.

3. Hypochlorous acid. Hypochlorous acid is prepared by dissolving chlorine in water, which has strong oxidizing properties and can be bleached.

4. Concentrated nitric acid. Strong oxidizing properties, decolorizing and bleaching of substances.

5. Hydrogen peroxide. Commonly known as hydrogen peroxide, it has strong oxidizing properties, which allows it to be bleached.

Bleaching: Adding chemicals (oxidizing or reducing agents) to water to make things fade or whiten. It is the property of destroying and inhibiting the color of food, fading it or preventing browning of food, some chemicals, through oxidation reaction to achieve the function of bleaching articles, and bleaching some articles is to remove or lighten its color.

The chemical bleaching agents commonly used to make bleaching work are generally divided into two categories: chlorine bleach and oxygen bleach.