Sciencemadness Discussion Board

Venting Sodium Bisulphate

curiousmatt - 14-5-2013 at 07:53

If this is in the wrong forum I do apologize. I am no chemist and know little of chemistry but I do have a couple important questions if anyone is willing to help. Without getting into to many details the basic problem I have is that I have a machine applying sodium bisulphate onto cloth. The sodium bisulphate is being heated up enough to cause steam. This is in a heavy container and instead of venting this we are diluting it with water. Should we vent this gas to the outside? Can sodium bisulphate change into sulfur dioxide?

blogfast25 - 14-5-2013 at 09:23

Quote: Originally posted by curiousmatt  
Can sodium bisulphate change into sulfur dioxide?


When actually fused (melted) SO3 fumes are generated, quite nasty is that. I doubt if in your conditions that actually happens. Regards SO2, it has a distinct and quite pungent odour, if you can't smell any of it you should be ok to vent it outside.

curiousmatt - 14-5-2013 at 09:38

Thank you blogfast for helping me out. I did not think we could be producing SO3 but I was just being cautious. The smell is awful you are correct on that.

ElectroWin - 14-5-2013 at 10:13

SO2 is so stinky that you can smell that brimstone odour even in trace amounts; if there is no smell like burning matches, then no SO2.

ScienceSquirrel - 14-5-2013 at 12:20

I use sodium metabisulphite as a routine mild bug killer and the soild and solution have that familiar choking smell.
Sulphur dioxide, once smelt, never forgotten!

woelen - 14-5-2013 at 12:44

Sodium bisulfate does not give off SO2 when heated. The usual product of commerce is NaHSO4.H2O and the H2O easily is given off (at temperatures well below 100 C quite some water vapor is released). At temperatures of a few 100 C another molecule of H2O is split off and you get Na2S2O7. Before SO3 is given off you have to heat to 1000 C or so (red hot, normal glass melts at a lower temperature than the temperature at which Na2S2O7 releases SO3). So, in your situation you won't have any SO2, nor SO3. It is safe to vent the gasses outside.

Of course, there can be certain smells, but either these are from impurities in the NaHSO4.H2O, or these are due to smelly things in the cloth.