Bromate Reduction (with specific requirements)

[battousai]

In a solution with both BrO3- and Br-, does anyone know how to reduce the BrO3- to Br- without oxidising the pre-existing Br- to Br2? Also, only potassium ions can be introduced into the solution.

 

My first thought is, to use hydrogen peroxide or potassium permanganate, but I believe this would oxidise the Br- to Br2.

 

Does anyone have any ideas?

[John Cuthber]

Try adding a reducing agent.

If you don't want Br2 formed you have to keep the solution alkaline.

[battousai]

If I were to use aluminum or zinc, would the majority of the BrO3- be reduced, forming solid aluminum or zinc oxide, with the respective oxide remaining inert to the solution?

[dlzc]

In a solution with both BrO3- and Br-, does anyone know how to reduce the BrO3- to Br- without oxidising the pre-existing Br- to Br2? Also, only potassium ions can be introduced into the solution.

 

My first thought is, to use hydrogen peroxide or potassium permanganate, but I believe this would oxidise the Br- to Br2.

 

Does anyone have any ideas?

 

"breakpoint bromination"... add a stoiciometric amount of ammonia.

[battousai]

dlzc, could you explain please?

 

For the chem experts, would H2, be a strong enough reducting agent with BrO3- to produce, H2O and Br-?

[dlzc]

dlzc, could you explain [about breakpoint bromination] please?

 

Various oxidized halogens are added to waters containing ammonia, to neutralize the ammonia to nitrogen gas and water. The process is called breakpoint chlorination, bromination, or iodation (etc.). and they are added in precise amounts... resulting in a rapid conversion (high rate constant). These are discussed in literature, and well known in swimming pool chemistry (probably inclusive of salt water aquaria).

 

The same can be applied with ammonia added in suitable amounts to neutralize the "excess" oxidized halogens.

[verode]

Just Al +NaOH with bromates only gives bromides