LanthanumK - 1-7-2011 at 04:44
Once, I melted sulfur in a test tube and could not get it clean. After reading on Wikipedia that thiosulfate is produced by heating sulfur with an
aqueous solution of a metal sulfite, I was wondering if this is a good way to remove sulfur residues from glassware as thiosulfate is soluble in
water.
barley81 - 1-7-2011 at 04:57
Sounds good to me. It also makes a useful product. Toluene can also be used to dissolve sulfur.
Woelen has a page about recrystallizing sulfur with toluene:
http://woelen.homescience.net/science/chem/exps/S+toluene/in...
Bot0nist - 1-7-2011 at 04:59
Soak in and wash with boiling water if toluene isn't available.
Jor - 1-7-2011 at 05:15
Use hot sodium hydroxide solution, this is the cheapest, most effective way and most environmental friendly solution. The sulfur disproportionates in
alkaline environment to sulfide and thiosulfate (I am not completely sure of the latter). The former can dissolve even more sulfur to give
polysulfide-ions.
UnintentionalChaos - 1-7-2011 at 05:21
Hot NaOH solution should remove traces fairly quickly. Hot toluene/xylene will work better on bulk material though. Have you considered merely heating
it with air exposure. If there isn't gunk in the sulfur (like in gardening sulfur), it should evaporate/burn away cleanly. I wouldn't do this to round
bottom flasks because of the heat stress but test tubes are cheap.
LanthanumK - 1-7-2011 at 11:39
I didn't know there were so many ways. Why do they always recommend to use an old test tube when melting sulfur if it is removed relatively easily?