Chemical laboratories generally need to use various chemical reagents. In addition to daily use, they also need to store a certain amount of chemical reagents. Most of the chemical reagents have certain toxicity, and some are inflammable and explosive dangerous goods. Therefore, it is particularly important to understand the properties and storage methods of general chemicals. A large amount of chemicals should be placed in the sample storage room and kept by special personnel. Dangerous goods shall be stored according to the management regulations of the national security department.
First of all, remember: isolated storage!
Inflammable, highly toxic, highly corrosive, low-temperature storage, etc. shall be classified and placed; Laboratory and warehouse management personnel are required to have certain relevant knowledge. Store in the medicine cabinet with ventilation, shade and temperature lower than 30 ℃. Some drugs are easy to decompose when exposed to light, so they should be kept away from light. Solid and liquid; Acid and alkali shall be placed separately.
1. General requirements for preservation of reagents
① The laboratory shall try not to store or store chemical reagents as little as possible, so as to prevent the pollution of reagent volatiles to the laboratory and avoid the influence of substances produced by chemical experiments on chemical reagents. If conditions permit, there shall be room for storing chemical reagents;
② Keep a certain temperature and humidity in the room. Avoid strong light irradiation and have good exhaust equipment;
③ The chemical reagents shall be placed in the special glass reagent cabinet which can prevent dust and prevent various vapors or gases from being stained and eroded. It shall be stored according to the nature of reagents;
④ For stored reagents, always check whether the labels on the bottles are intact and whether the handwriting is clear. In case of falling or blurring, it shall be replaced in time;
⑤ Fire protection equipment and sandbox shall be provided indoors.
2. Storage requirements and precautions for various special reagents
(1) Substances liable to interact with air components:
① Substances liable to interact with oxygen:
Sodium, potassium, calcium and other active metal elements shall be stored in isolation from air and generally in kerosene or paraffin. Lithium shall be stored in paraffin oil.
White phosphorus needs to be stored in water. Iron powder, ferrous salt, stannous salt, sulfite and its salts, hydrogen sulfate and its salts, sodium thiosulfate, phenol, etc. shall be stored in a closed manner.
② Substances liable to interact with water:
Sodium, potassium and calcium shall be stored in kerosene. Calcium carbide, quicklime, anhydrous copper sulfate, sodium oxide, sodium peroxide, magnesium nitride, aluminum sulfide and other substances can react with water and should be sealed and stored. Concentrated sulfuric acid, sodium hydroxide solid, calcium chloride, magnesium chloride, tin tetrachloride, phosphorus pentoxide, alkali lime, silica gel, concentrated phosphoric acid and other substances are prone to water absorption or deliquescence, and should be sealed and stored.
③ Substances liable to interact with carbon dioxide:
Alkali substances (such as sodium hydroxide, calcium hydroxide, etc.), weak acid salt substances (such as sodium silicate, bleaching powder, etc.), sodium peroxide, alkali lime and other substances shall be sealed and stored.
(2) Easily decomposed substances:
Concentrated nitric acid, silver nitrate, silver bromide, silver iodide, chlorine water, bromine water, potassium permanganate, hydrogen peroxide and other substances that are easily decomposed by light should be stored in brown bottles and placed in the dark. Silver bromide and silver iodide shall be stored in a dark room.
(3) Volatile substances:
Concentrated hydrochloric acid, concentrated nitric acid, concentrated ammonia water and all organic solvents shall be sealed and placed at low temperature. Liquid bromine is toxic and volatile. It needs to be put in a grinded fine mouth bottle, sealed with water, then plugged with a glass stopper, sealed with wax and placed in a cool place.
(4) Substances liable to Sublimation:
Naphthalene, anthracene, iodine and other substances are easy to sublimate and should be sealed and stored at low temperature.
(5) Substances easy to interact with glass:
Sodium hydroxide, potassium hydroxide, etc. are easy to interact with the silica in the ground glass and can adhere to the glass plug. Therefore, they should be stored in sealed containers with rubber plugs. Water glass itself has a strong role of adhering to glass, so it cannot be stored in containers with glass plugs. Hydrofluoric acid can react with silica in glass due to its strong corrosiveness. Therefore, it cannot be stored in glass bottles, but in plastic bottles.
(6) Flammable substances:
① Flammable liquids:
Mainly organic solvents, such as ethanol, ether, acetone, carbon disulfide, benzene, toluene, gasoline, etc., which are easily volatilized into gas and will be burned in case of open fire. Therefore, these liquids should be sealed and stored separately. Attention should be paid to: cool, ventilated and away from fire source.
② Flammable solids:
The ignition point of sulfur, red phosphorus, magnesium powder, aluminum powder and other substances is very low, and the storage place should be ventilated and dry.
(7) Substances liable to cause poisoning:
Cyanide, arsenic trioxide or other arsenide, mercury dichloride, etc. are highly toxic reagents, and a small amount of them may cause poisoning death if they invade the digestive tract; Soluble copper salt, barium salt, lead salt and antimony salt can also cause poisoning. Therefore, these reagents should be kept properly. Highly toxic substances shall be kept by special personnel.
(8) Explosive substances:
① Substances that burn and explode in water:
Sodium, potassium, calcium, calcium carbide, zinc powder, etc. can react violently with water and release combustible gas, which is very easy to cause explosion. Therefore, these substances should be isolated from inflammables, strong oxidants, etc. and sealed for storage.
② Substances causing explosion due to strong redox reaction:
Strong oxidizing substances such as peroxides (such as hydrogen peroxide, sodium peroxide and barium peroxide), strong oxidizing oxyacids (such as perchloric acid) and strong oxidizing salts (such as nitrate, chlorate, dichromate and permanganate) may cause explosion when heated, impacted or mixed with reducing substances. Therefore, it must not be stored together with combustibles, combustibles and reducing substances. It should be stored in a cool and ventilated place.