Bromine: reactions of elements

Reaction of bromine with air

Bromine, Br2 is not reactive towards with oxygen, O2, or nitrogen, N2. However, bromine does react with ozone, O3, the second allotrope of oxygen, at -78°C to form the unstable dioxide bromine(IV) oxide, BrO2.

Br2(l) + 2O3(g) → O2(g) + 2BrO2(s) [brown]

Reaction of bromine with water

Bromine, Br2, reacts with water to produce hypobromite, OBr-. The position of the equilibrium depends very much upon the pH of the solution.

Br2(l) + H2O(l) ⇌ OBr-(aq) + 2H+(aq) + Br-(aq)

Reaction of bromine with the halogens

Bromine, Br2, reacts with chlorine, Cl2, in the gas phase to form the interhalogen species BrF. The product is difficult to obtain pure since BrF disproportionates at room temperature to form bromine, Br2, and BrF3 and BrF5.

Br2(g) + F2(g) → 2BrF(g)

3BrF(g) → Br2(l) + BrF3(l)

5BrF(g) → 2Br2(l) + BrF5(l)

Under more forcing conditions, excess fluorine reacts with bromine, Br2, at 150°C to form the interhalogen species BrF5.

Br2(l) + 5F2(g) → 2BrF5(l)

Chlorine, Cl2, reacts with bromine, Br2, in the gas phase to form the unstable interhalogen species bromine(I) chloride, ClBr.

Cl2(g) + Br2(g) → 2ClBr(g)

Similarly, bromine, Br2, reacts with iodine, I2, at room temperature to form the interhalogen species bromine(I) iodide, BrI.

Br2(l) + I2(s) → 2IBr(s)

Reaction of bromine with acids

Reaction of bromine with bases

Bromine, Cl2, reacts with hot aqueous alkali to produce bromate, BrO3-. Only one sixth of the total bromine is converted in this reaction.

3Br2(g) + 6OH-(aq) → BrO3-(aq) + 5Br-(aq) + 3H2O

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