Safe handling and storage of chemicals
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Storage of many chemicals require additional or special requirements, to avoid hazards as well as contamination.
- 1 Storage area guidelines
- 2 Storage of specific materials
- 3 Handling
- 4 Incompatible chemicals
- 5 References
Storage area guidelines
Storage cabinets and shelves
- Oxidizing acids and flammable solvents must be stored in separate locations.
- Solvents in general must be stored away from any source of heat and light.
- Hazardous materials, especially those that are water sensitive, should not be stored under sinks (except cleaners).
Corrosive chemicals cabinet
Strong acids are usually stored here
- Such cabinets should either be made from chemical resistant materials or lined with such.
- A double door is recommended.
- Scrubbers are optional, but recommended. A open container of baking soda should take care of acidic vapors.
- Do not store metals or other reducing chemicals in the same cabinet.
- Do not store nitrates and oxochlorine anions in the acids cabinet.
- Amines should also not be stored in the same cabinet as acids, as their fumes will react to form a very fine dust.
Refrigerators can be used to store volatile substances and to cool exothermic reactions. Although domestic refrigerators can be used to store many chemicals, they are unsuitable for storing corrosive chemicals, such as acids. Several important guidelines:
- Avoid storing acids, as the escaping vapors will corrode the refrigerator.
- Do not store food in the same refrigerator. Do not reuse a chemical refrigerator for food.
- Avoid storing the cryogenic container in light or near a heat source.
- Periodically check the valves.
- Always ensure that cryogenic container has a pressure release valve
- Always turn on the cooling first before performing any other operation.
- Ethers must never be distilled to dryness, as they tend form explosive peroxides during storage that can explode when dry.
- Never store solvents in plastic containers, even those which are supposed to be insoluble in the solvent.
- Periodically open the lids of chemicals which decompose, to allow pressure buildup to release itself. ALWAYS do this when you move a solvent bottle from a cold place to a warm one (some solvents have a very high vapor pressure and can burst if too much pressure builds up inside the reagent bottle).
- Although it is usually not a safety hazard, make sure to store dehydrated chemicals in completely sealed,(usually) glass, containers.
Storage of specific materials
Lithium poses an unusual problem in that it is lighter than almost every single nonpolar organic solvent. The only ones in which it sinks are liquid ethane and methane. Weighting pieces of lithium down with a heavier metal, such as copper or lead, is common practice.
Sodium is more reactive than lithium, but it's denser than mineral oil and most organic solvents and can be easily stored for months.
Potassium is more reactive than the first two and while it can be stored under mineral oil, it will corrode much faster. Sealing the bottle is recommended. Ampouling is sometimes used.
Rubidium and Cesium
Both Rubidium and Cesium are extremely reactive and even pyrophoric. They can only be stored under mineral oil for short periods, ampouling is used instead.
Unlike the pure alkali metals, the sodium-potassium mixture, in a 77:23 K-Na ratio, is liquid at standard conditions. It is pyrophoric and less dense than water. It is usually stored under hexane or ampouled, since it's lighter than most organic solvents used to store alkali metals. It will also corrode PTFE.
Ethers stored for long periods of time in contact with air will form explosive peroxides, that are a hazard, usually during the distillation, or when opening the storage bottle. Ethers like dimethyl ether, methyl tert-butyl ether or di-tert-butyl ether do not form explosive peroxides, while common ethers, like diethyl ether or THF will slowly form explosive peroxides over the course of several months. Diisopropyl ether tends to form explosive peroxides much easier than the former two, and its use in chemistry is generally avoided. To avoid this unpleasant effect, adding small amounts of an anti-oxidant like BHT (butylated hydroxytoluene), or a clean copper wire will prevent the formation of peroxides. Iron(II) sulfate can also be added to neutralize the peroxides. Sodium hydroxide flakes are also added to precipitate any forming peroxides. Ethers in general are never distilled to dryness, as ether peroxides tend to explode when dry. Adding dry glycerin may help in keeping the distillation residue wet.
Bromine is extremely difficult to safely store, as its vapors will escape the storing bottle and corrode most metals and many plastic materials. Sealing the storage bottle with parafilm or PTFE will slow the vapors from escaping, but parafilm will eventually degrade, and needs to be replaced periodically. Ampouling is recommended, though sealing the ampoule is complicated by the volatility of bromine. Unlike iodine vapors, the bromine ones are more toxic, and is recommended that the bottle should be stored in a container with a scrubbing agent, like a thiosulfate salt, inside the storage cabinet.
Iodine is notorious for escaping the storage vessel, as well as corroding almost any material, except glass and noble metals. Its vapors will destroy aluminium, severely corrode iron and its alloys and irreversibly stain most plastic materials. Ampouling is recommended, while sealing the bottle with parafilm or PTFE will only slow its escape. Since its vapors aren't as dangerous to health as bromine, simple storing the container in a corrosive cabinet is usually sufficient.
White phosphorus should be tightly sealed in an extremely durable container, away from light to prevent degradation. WP can be safely stored underwater.
Hydrofluoric acid should never be kept or handled in glass containers (e.g. beakers), because of its ability to dissolve (most) oxides and silicates. It should be handled in thick plastic containers.
The maximum concentration at which perchloric acid can be safely stored is 70%. As it is a very powerful oxidizer, all the glassware where is about to be poured in should be inspected for any organic traces.
|Chemical||Keep out of contact with||Additional notes|
|Acetic acid||Alkali metals, chloric acid, chlorosulfuric acid, chromium (VI) oxide, ethylene glycol, ethylene-imine, hydrogen peroxide, hydroxyl compounds, manganese (VII) oxide, magnesium, metal hydrides, nitric acid, oleum, perchloric acid, peroxides, permanganates, potassium tert-butoxide, PCl3||Fire hazard|
|Acetic anhydride||Alkali metals, chloric acid, chlorosulfuric acid, chromium (VI) oxide, ethylene glycol, ethylene-imine, hydrogen peroxide, hydroxyl compounds, manganese (VII) oxide, magnesium, metal hydrides, nitric acid, oleum, perchloric acid, peroxides, permanganates, potassium tert-butoxide, PCl3, water||Fire hazard|
|Acetone||Hydrogen peroxide||Fire and explosive hazard|
|Acetone peroxide||Most common metals, static-prone materials (cloths)||Explosive hazard|
|Acetonitrile||Acetic acid, acids, alkali metals, bases, chromic acid, nitrating agents, nitric acid, oleum, perchlorates, reducing agents, sodium peroxide, steam, diphenyl sulfoxide, trichlorosilane, certain plastics (ABD, CPVC, PVC)||Fire hazard and decomposition|
|Acetylene||Alkali hydrides, brass, bromine, chlorine, copper, copper salts, fluorine, mercury, mercury salts, nitric acid, potassium. silver, silver salts||Fire and explosive hazard|