jamit - 30-8-2011 at 03:31
I've been reading the board lately on hydrobromic acid and attempting to distill it but I've ran into some problems with bumping.
After's adding sulfuric acid to sodium bromide in 1:1 molar ratio, and putting that in an ice bath to ppt sodium bisulfate as much as possible... I
setup for simple distillation.
The first to come over is mostly water and that there was no problem... the temperature than shot up to around 122-125C. I changed receiving flask to
collect the hydrobromic acid.
After about 30 minutes, the bumping started... I put in boiling stones before the distillation but that was useless as it just floated and would not
submerged. The bumping become too violent so I shut off the heating mantle and waited for it to cool. Afterward, I put 5 pieces of broken stirring
rod and removed any crystallized sodium bisulfate by decanting the solution into another 500ml rbf. Again I setup for simple distillation.
Again everything was fine but after awhile (about 20mins) the bumping began again. What am I doing wrong? How can I stop the bumping?
Any help would be greatly appreciated. thanks.
AndersHoveland - 30-8-2011 at 07:03
One does not distill bromides with sulfuric acid, because the HBr tends to get oxidized by the H2SO4.
It is best to use phosphoric acid instead.
jamit - 30-8-2011 at 19:34
can you use 40-50% phosphoric acid to do this or does it have to be 85% phosphoric acid?