There are many methods of reagent classification. If according to the state can be divided into solid reagent, liquid reagent. According to the use can be divided into general reagent, special reagent. According to the category can be divided into inorganic reagent, organic reagent. According to the performance can be divided into dangerous reagent, non-dangerous reagent and so on. Chemical reagents are also called chemicals, referred to as reagents. Chemical reagents refer to various elements and compounds (can also be mixtures) with a certain purity standard. Any experiment can not be carried out without reagents, reagents not only have various states, but also different reagents have very different properties. Some are very stable at room temperature, some are usually very lively, some are not deteriorated by high temperature, and some are flammable and explosive: some have a strong aroma, and some are highly toxic. Only with a deep understanding of the relevant knowledge of chemical reagents can we safely and smoothly carry out various experiments. It can not only ensure the expected experimental purpose, but also eliminate the pollution to the environment. Therefore, the first thing to know is the classification of reagents. Then master the storage and use of various reagents.

Classification of chemical reagents

From the perspective of storage and use of reagents, reagents are often classified by category and performance.

Inorganic reagent and organic reagent

This classification method is consistent with the classification of chemical substances, which is easy to identify, remember, and store and access. Inorganic reagents are classified according to elemental, oxide, base, acid and salt, and then their properties are considered. Organic reagents are classified according to hydrocarbons, hydrocarbon derivatives, carbohydrate proteins, macromolecular compounds, indicators, etc. This classification of hazardous and non-hazardous reagents takes into account both practicality and the characteristic properties of reagents. Therefore, it is not only convenient for safe storage, but also convenient for experimental workers to comply with the safe operation rules when using.

Classification of dangerous reagents

According to the nature and storage requirements of dangerous reagents, it is divided into:

(1) Flammable reagents This type of reagent refers to a chemical substance that can spontaneously ignite in the air or easily cause combustion in the presence of other substances. Due to the different existence state or causes of combustion, it can be divided into: ① easy spontaneous combustion reagents: such as yellow phosphorus. ② Water burning reagents: such as potassium, sodium, calcium carbide and so on. ③ Flammable liquid reagents: such as benzene, gasoline, ethyl ether, etc. ④ Flammable solid reagents, such as sulfur, red-phosphorus, aluminum powder, etc.

(2) Explosive reagents refer to chemical substances that are subjected to violent chemical reactions caused by external forces and can emit a large number of harmful gases at the same time. Such as potassium chlorate, etc.

(3) Toxic agents refer to chemical substances that are strongly toxic to people or organisms and the environment. Such as bromine, methanol, mercury, trioxy-arsenic, etc.

(4) Oxidizing reagents refer to substances that can oxidize other substances and themselves are reduced, such as sodium peroxide, potassium permanganate, ammonium bichromate, ammonium nitrate, etc.

(5) Corrosive reagents refer to chemical substances that are strongly corrosive and can destroy the human body and other items due to corrosion, and even cause combustion, explosion or casualties, such as strong acid, strong alkali, anhydrous aluminum chloride, formaldehyde, phenol, hydrogen peroxide, etc. Classification of non-hazardous reagents

The properties and storage requirements of non-hazardous reagents can be divided into:

(1) Reagents that are easily deteriorated in the event of light refer to substances that are affected by ultraviolet light, which are easy to cause the decomposition and deterioration of the reagent itself, or to promote chemical changes between the reagent and the composition of the air. Such as nitric acid, silver nitrate, ammonium sulfide, ferrous sulfate and so on.

(2) In case of heat easily deteriorated reagents Such reagents are mostly biological products and unstable substances, decomposition, mildew, fermentation can occur at high temperatures, and some are also normal temperature. Such as ammonium nitrate, ammonium carbide, AGAR and so on.

(3) Easily frozen reagents The melting point or freezing point of this kind of reagent is within the temperature change, when the temperature is higher than its melting point, or falls below the freezing point, the reagent due to melting or solidification and volume expansion or contraction, easy to cause the reagent bottle burst. Such as glacial acetic acid, crystal sodium sulfate, crystal sodium didian acid and bromine aqueous solution.

(4) Weathering reagents This type of reagent itself contains a certain proportion of crystal water, usually crystal. At room temperature, in dry air (general relative humidity below 70%), some or all of the crystal water can be gradually lost and some become powder. It is difficult to master its content when using. Such as crystalline sodium carbonate, crystalline aluminum sulfate, crystalline magnesium sulfate, gall alum, alum and so on.

(5) Delixing reagent This kind of reagent is easy to absorb the moisture (moisture) in the air to produce delixing, deterioration, shape change, content reduction and even mildew. Such as ferric chloride, anhydrous sodium acetate, methyl orange, AGAR, reduced iron powder, aluminum silver powder, etc.

Source: Instrument Information Network