What is bromine?

Bromine is a deep reddish brown liquid. It is also the only non-metallic element in liquid form at room temperature. It has a pungent odor and is highly corrosive. Bromine was discovered in 1842 and the use of bromine and its compounds is very extensive.

In November 2017, according to the provisions of Article 2 of the Regulations on the Administration of Precursor Chemicals, the State Council agreed to add the list of the Classification and Variety List of Precursor Chemicals in the Schedule to the Regulations on the Management of Precursor Chemicals. Addition of bromine to the second class of precursor chemicals

Related reactions: Chlorine and bromine are elements of the same main group, and their chemical properties are similar. Some common bromine-related chemical reactions are listed below.

Dissolving the bromine in water to obtain hydrobromic acid (HBr) and hypobromous acid (HOBr or HBrO);

Bromine dissolved in potassium hydroxide to obtain potassium bromide, potassium hypobromite;

The bromine vapor and hydrogen are ignited to produce hydrogen bromide, and the hydrogen bromide is dissolved in water to obtain hydrobromic acid;

Displacement reaction between bromine water and potassium iodide solution: Br2+KI=I2+KBr (addition of CCl4 organic layer is purple-red);

The combination of bromine and sodium metal reacts violently to produce sodium bromide;

Liquid bromine can be combined with benzene under the catalysis of iron (iron tribromide) to form bromobenzene.

Process: The laboratory can be prepared by mixing potassium bromide, potassium bromate and concentrated sulfuric acid to prepare bromine. Generally, the bromine water used in the experiment (when the requirement is not high) can be directly prepared by using a chlorine gas generating device to pass a saturated solution of potassium bromide.

Toxicity: Bromine vapor can burn mucous membranes even at low concentrations, causing cough, increased mucosal secretions, nosebleeds, dizziness and other symptoms. Liquid bromine is strongly corrosive to the skin and can form scars that are difficult to heal. The maximum allowable concentration of bromine vapor in air is 0.5 mg/m3. Poisoning 30 to 40 minutes can be fatal.

Protective measures: Workers must wear protective gear such as overalls, rubber gloves, aprons, goggles and filter masks. Avoid contact with the skin. When the skin is burning, rinse with plenty of water, then apply ointment and send it to hospital for treatment.

Packing, storage and transportation: Packed with acid-resistant ceramic altar or glass bottle, sealed at the mouth of the altar (bottle) or sealed with wax or gypsum. Industrial bromine has a net weight of 25kg or 30kg per litter. The altar (bottle) is placed in a wooden box, and a cushion is placed between the box and the altar (bottle) to prevent smashing. There should be obvious “drugs” and “corrosives” signs on the packaging. It is a Class I inorganic acid corrosion item, dangerous code number: 91030. It should be stored in a cool, ventilated, dry warehouse. To prevent exposure to sunlight, it should be isolated from fire and heat sources, and should not be stored and transported with ammonia, phosphorus, aluminum powder and alkali. Keep away from flammable materials such as wood chips, shavings, and straw to prevent burning. Handle with care during transportation and handling to avoid breakage of the altar (bottle). In case of fire, use water, dry sand, carbon dioxide fire extinguisher to save.

Relevant national standards: GB/T 1281-2011 Chemical reagents Bromine [2]

Relevant knowledge: It should be noted that commercially available bromine is divided into bromine (liquid bromine, bromine) and bromine water. Bromine is a simple substance of bromine and bromine water is a 3% aqueous solution of bromine. The two are completely different. of. Bromine (liquid bromine, Br2) is a deep reddish brown liquid, bromine water is an orange-yellow liquid (an aqueous solution of bromine, the main component Br2), and bromine vapor is a reddish brown gas. Bromine vapor and nitrogen dioxide can be identified by adding water, silver nitrate solution, carbon tetrachloride or the like.