There are many methods of reagent classification. Such as according to the state can be divided into solid reagent, liquid reagent. According to the use can be divided into general reagents, special reagents. According to the category can be divided into inorganic reagents, organic reagents. According to the performance, it can be divided into dangerous reagents, non-dangerous reagents, etc. Chemical reagents are also called chemicals, referred to as reagents. Chemical reagents refer to various simple substances and compounds (also can be mixtures) with certain purity standards. To carry out any experiment can not be separated from the reagent, the reagent not only has a variety of states, but also the performance of different reagents is very different. 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 strong aroma, while others are highly toxic. Only the knowledge of chemical reagents in-depth understanding of the safe and smooth conduct of the experiment. It can not only ensure the expected experimental purpose, but also eliminate the pollution to the environment. Therefore, we must first know 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 and organic reagents

This classification method is consistent with the classification of chemical substances, which is convenient for identification, memory, storage and access. Inorganic reagents are classified according to simple substance, oxide, alkali, acid and salt, and then classified by nature. Organic reagents are classified by hydrocarbons, hydrocarbon derivatives, carbohydrate proteins, polymer compounds, indicators, etc. This classification of hazardous agents and non-hazardous agents not only pays attention to practicality, but also takes into account the characteristic properties of reagents. Therefore, it is not only convenient for safe storage, but also convenient for laboratory workers to abide by safe operation rules when using.

Classification of hazardous reagents

According to the nature and storage requirements of hazardous reagents, they are divided:

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

(2) The explosive reagent refers to the chemical substance which is caused by the violent chemical reaction under the action of external force and can release a large amount of harmful gas at the same time. Such as potassium chlorate.

(3) Toxic agents refer to chemical substances that are highly toxic to humans or organisms and the environment. Such as bromine, methanol, mercury, three oxygen-arsenic, etc.

(4) oxidizing reagent refers to the oxidation of other substances can play a role in the reduction of their own substances, such as sodium peroxide, potassium permanganate, ammonium dichromate, nitrate-ammonium acid and so on.

(5) Corrosive reagent refers to a strong corrosive, the human body and other items can be damaged due to corrosion, and even cause combustion, explosion or casualties of chemical substances, such as strong acid, alkali, anhydrous aluminum chloride, formaldehyde, phenol, hydrogen peroxide and so on. Classification of non-hazardous reagents

The nature and storage requirements of root non-hazardous reagents can be divided:

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

(2) Reagents that are easy to deteriorate when exposed to heat. These reagents are mostly biological products and unstable substances. Decomposition, mildew and fermentation can occur at high temperatures, and so can some at room temperature. Such as nitrate-ammonium acid, ammonium carbonate, agar, etc.

(3) easy to freeze reagent 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 volume expansion or contraction of the reagent occurs due to melting or solidification, which is easy to cause the explosion of the reagent bottle. Such as glacial acetic acid, crystalline sodium sulfate, crystalline sodium dianide, and aqueous solution of bromine.

(4) easy weatherable reagent This kind of reagent itself contains a certain proportion of crystal water, usually crystal. At room temperature in dry air (generally relative humidity below 70%) can gradually lose part or all of the crystal water and some become powder. It is not easy to grasp its content when used. Such as crystalline sodium carbonate, crystalline aluminum sulfate, crystalline magnesium sulfate, alum, alum, etc.

(5) easy deliquescence reagent This kind of reagent is easy to absorb moisture (moisture) in the air to produce deliquescence, 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.