THX-1138

'S what I thought. However, I haven't been able to find any reference for the temperature at which it starts to break down. Any pointers? Ta..

I have some finely-divided iron disulfide, possibly mixed with some other things, that I wish to 'dissolve' away -- or at any rate remove from the mix. What would be a good way of doing this using fairly safe chemicals? (I.e., not concentrated nitric acid, although H2SO4 or HCl are possible.) Among the things that may be left behind are SiO2 and microscopic amounts of gold, neither of which I'm concerned about being affected by the solvents. If I heat FeS2, won't it break down and leave me with elemental Fe and SO2? If so, perhaps then I could act directly on the iron and make it into a soluble compound that could be dissolved and washed away..

Gaah. I just looked at the MSDS for toluene, and it's not something I'll be prepared to mess about with for quite some time, if ever. Just as well..

I'm actually not trying to purify it myself, at least not right now. This jar is still pretty full, it was tightly sealed, and I don't have any projects needing it at the moment. Although that's good information if I decide to play mad scientist with the sack of garden sulphur out in the shed.. I just got curious about the industrial process. As for sublimation versus deposition, a lot of geology sources seem to use 'sublimation' primarily for the gas->solid transition, especially with regard to volcanic by-products.

Mm, I was able to figure that much out. But is it done in an inert environment? What material is used for the deposition surface? (Thanks for that correction/reminder, by the way.) How much is done at a time? How are accumulated impurities handled? Questions, questions. What would happen if you passed the gaseous S over a chilled non-solvent liquid? I'm thinking ease of collection here. Just curious, and I haven't had my caffeine-analogue yet this morning..

In rummaging through my shelves, I came across a bottle of pharmaceutical-grade sulphur, the label of which remarks that it was sublimated. That ticked my curiousity, so I went looking to see how you'd sublimate sulphur in commercial quantities. I came up empty on that, although I did learn that the sublimation process in question is from gaseous to solid phase. (I guess I subconsciously associated 'sublimation' with a solid->gaseous transition from the rather more common dry ice.) So.. Just how do they sublimate sulphur in large quantities? I presume its purity would be affected by contaminants on the condensing surface, and any in the sample that had phase transitions very close to S's, so sulphur obtained by sublimation isn't necessarily 100% 'pure.' Just probably pretty close.

I'm sure this has been asked NA times, but I haven't been able to find a clear answer -- just bits and pieces as parts of larger discussions. My chemistry classes are many years in the past now, so I might not even be asking sensible questions. However.. I'm looking for formulae relating concentrations, pH, and molarity to each other, for strong acids/bases. For example, I have here a bottle of industrial H2SO4 for which the MSDS claims the 'Hazardous Components: Sulfuric Acid 93.2%'. Is it safe to assume that's w/w? Presuming the other 6.8% is water, how can I determine the molarity and pH? Thanks in advance..