a123x - 17-7-2003 at 15:32
I'm trying to come up with a practical way to make sodium sulfide with easily obtainable chemicals. I'm thinking something like reacting an
insoluble sulfide such as iron sulfide(since I can just buy some at a mineral shop) with dilute sulfuric or hydrochloric acid. The reaction should
evolve toxic hydrogen sulfide but considering iron sulfide is insoluble and I'll be using dilute acids I wouldn't expect it to be very rapid
at all. Anyway this is done in a stoppered flask with a tube running into another stoppered flask filled with ammonium hydroxide solution to bubble
the H2S through it. Another tube comes out from this flask(from above the solution) and runs into another solution of ammonia. I figure that since the
H2S evolution should be slow and an excess of ammonia solution all the H2S will be converted to ammonium sulfide. The solution is boiled to remove
remaining ammonium hydroxide and then reacted with NaOH giving Na2S and more ammonia to just boil off. I would just bubble H2S directly into NaOH
solution but I want an excess of base to ensure full reaction with the H2S and at the end it is easier to remove ammonium hydroxide excess than NaOH
excess. Does my reasoning here have any flaws in it?
Marvin - 18-7-2003 at 10:26
How about,
Dissolving S in NaOH solution and seperating the sulphide?
Sodium hydroxide or carbonate, sulphur, carbon and heating to red heat to produce just sulphide and carbon.
Reducing sodium sulphate with carbon at a slightly higher heat?
Reducing CaSO4 with C might require a temperature not easily managable.
H2S apart from being rather toxic and unpleasent, above a certain concentration we cant smell it anymore.
a123x - 18-7-2003 at 11:34
I thought that dissolving S in NaOH tends to not properly work for making picramic acid, the intended use of the sodium sulfide. Then again
that's using the solution directly, I hadn't really considered evaporating off the water to get the pure sulfide. I've found that my
method won't work anyway because ammonium sulfide decomposes into ammonia and H2S from heating at lowish temperatures so I wouldn't be able
to remove the excess ammonium hydroxide. I'd suppose I could just use NaOH solution to bubble the H2S into. I'm not particularly worried
about H2S toxicity since it should be produced very slowly so that all of it should react with NaOH(aq) and even if it doesn't it shouldn't
build up so long as done outside.
kryss - 18-7-2003 at 12:30
Your best bet is to bubble it directly into NaOH - you may also find some polysulphide being formed.Although if you can get elemental sulphue id go
with that route.Any excess h2s u can remove by bubbling through peroxide solution - or bleach.
Na2S isnt very stable however and its very soluble in water - you'll find your solution loses H2S as you concentrate it ie a smelly process