Bromine Properties

Bromine

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Physical properties of Bromine :

• It is deep red colored, volatile  liquid.
• Bromine is poisonous and produces blisters on skin.
• It has pungent odour.
• It is soluble in water. Its aqueous solution is called bromine water.

Chemical properties :

1)  Reaction with NH₃ : Ammonium bromide & nitrogen is formed.

2NH₃ + 3Br₂ ——–> N₂ + 6HBr

6 HBr + 6NH₃   ———–> 6NH₄Br

Equation as a whole-

8NH₃ +3 Br₂ ——-> 6NH₄Br +N₂

2) Reaction with NaOH :

a)With  Cold and dilute NaOH : Sodium bromide & sodium hypo bromite is formed.

2NaOH +Br₂ ——-> NaBr +NaBrO (sodium hypo bromite) + H₂O.

b) With hot and concentrated NaOH : Sodium bromide & sodium  bromate is formed.

6NaOH + Br₂ —–>5 NaBr +NaBrO₃(sodium  bromate) +3 H₂O.

3) Reaction with Ba(OH)₂ solution (baryta water):

6Ba(OH)₂ + 6Br₂ —–>5 BaBr₂ (barium bromide) +Ba(BrO₃)₂ (barium    bromate)+ 6H₂O.

4) Reaction with hot and concentrated Na₂CO₃ solution : Sodium bromide & sodium  bromate is formed.

3Na₂CO₃+ 3Br₂ ——-> 5NaBr + NaBrO₃ + 3CO₂

5) Reaction with Ca(OH)₂ :  calcium bromo hypo bromite is formed.

Ca(OH)₂ +Br₂ ——–> CaOBr₂ (calcium bromo hypo bromite) + H₂O

6) Oxidizing properties :

In presence of moisture bromine acts as strong oxidizing agent.

a) It oxidizes SO₂ into H₂SO₄:

Br₂ +H₂O ——->2HBr +O

SO₂ + O+ H₂O  ——–> H₂SO₄

Equation as a whole-

Br₂ + SO₂ +2H₂O  —->H₂SO₄ +2HBr

b) It oxidizes sodium thio sulphate to sodium tetra thionate:

2Na₂S₂O₃(sodium thio sulphate) + Br₂  —-> Na₂S₄O₆( sodium tetra thionate) +2NaBr

c) It oxidizes sodium arsenite to sodium arsenate:

Br₂ +H₂O ——> 2HBr +O

Na₃AsO₃ +O ——> Na₃AsO₄

Equation as a whole-

Br₂ + H₂O + Na₃AsO₃(sodium arsenite)  ——–> 2HBr +Na₃AsO₄(sodium arsenate)

d) It displaces I₂ from KI:

2KI + Br₂ ———>2KBr +I₂

Test of bromine:

1)  Bromine is red colored liquid with pungent odour.

2) It turns starch iodide paper blue.

2KI +Br₂ ——-> 2KBr + I₂

I₂ +starch ——> blue color

Uses:

1)  As oxidizing agent.

2) As a germicide.

3) Br₂-water is used to test unsaturation in organic compounds.