Sodium bromate

Sodium bromate is an interesting oxidizer used in industrial batch dyeing. Weirdly enough, solutions of it can dissolve gold so it's sometimes used in gold mining. Sodium bromate must be handled with care as it's a possible carcinogen. The easiest way to make sodium bromate is using electrochemistry. I tried this method out.

To a 300ml beaker I added 50ml of saturated sodium bromide solution and a pinch of sodium dichromate. I then electrolyzed the mixture for 3 hours and 10 minutes. The power source was 12 volts DC at 24 amps. A carbon anode and a steel cathode were used. Anyway, after the electrolysis, the mixture was filtered to remove carbon particles and then chilled down to 10 C. Nice white crystals of sodium bromate precipitated as the mixture cooled. I filtered the mixture again to collect the sodium bromate. Then I dried the product. I was left with 1.23g of sodium bromate.

left = dried sodium bromate    right = pyrotechnic with sodium bromate and Mg

anode:  2 Br- ==> Br2 + 2 e-   /   cathode: H2O + 2 e- ==> 2 OH- + H2

Br2 + 2 OH- ==> BrO- + Br- + H2O  /  3 BrO- ==> BrO3- + Br-  /   Na+ + BrO3- ==> NaBrO3