Apparently, the maximum you can reach is about 65 % at 20 °C w/w (solubility 1930 g/L).
Either you can boil an excess amount of azeotropic HBr, which will release moist HBr. You can then use reflux, which will condense the water, or pass
the gaseous mixture through a calcium chloride trap (or both), and you get relatively dry HBr that you redissolve in your main solution.
Or you can get dry HBr by reacting sodium bromide with 85% phosphoric acid. Contrarily to sulphuric acid, phosphoric acid is not an oxidant, so you
should be able to get reasonable amounts of HBr gas using this path (please test before, though, I'm somewhat perplexed by the use of phosphoric acid
to get HBr, but it seems to work fine). |