Sciencemadness Discussion Board

Calcium Sulfide

camurgo - 12-8-2019 at 12:53

Hello,
I've been unable to find Calcium Sulfide (CaS) for sale in my region (Brazil).

The places I did find it overseas were, so far, ridiculously expensive. Apparently if I can manage to buy it from China it's gonna be cheaper, but my messages weren't returned yet.

Would anyone know of a seller to recommend?

Or maybe trying to make it should be my preferred route?

Captain Chlorate - 12-8-2019 at 13:17

Can u get h2so4 ? And calciumcarbonate caco3?

Sulfuric acid react with calcium carbonate
H2SO4 + CaCO3 → CaSO4 + CO2 + H2O


Edit : sry pls ignore it...i read caso4

[Edited on 12-8-2019 by Captain Chlorate]

DrScrabs - 12-8-2019 at 13:30

Mill Ca and Sulfur in a ballmill should work I guess.

PirateDocBrown - 12-8-2019 at 13:54

Just lime, hot water and sulfur, then purify.

Chemi Pharma - 12-8-2019 at 14:54

Quote: Originally posted by DrScrabs  
Mill Ca and Sulfur in a ballmill should work I guess.


I agree and think it's the only reasonable way to synthesizes CaS in a decent yield.
Quote: Originally posted by PirateDocBrown  
Just lime, hot water and sulfur, then purify.


This reaction will produce a mixture of sulfide, sulfite and tiosulfate that will be hard to separate, I guess. We can't forget CaS decomposes with water, so, I don't know if this reaction would be feasible. It's something similar to the process to synthesizes sodium sulfide from NaOH, sulfur and boiling water, like said in the Patent attached below.

NOTE: @Camurgo, I have already answered your U2U. Read my answer, don't be so surprised and call me back as soon as you can by U2U, ok?

Attachment: sodium sulfide.pdf (855kB)
This file has been downloaded 380 times

camurgo2 - 12-8-2019 at 15:30

@Chemi Pharma,

I created this secondary account just to let you know I'm currently locked out of my main account. As soon as this issue resolves I'll respond to your U2U.

Explanation: I forgot my password, clicked on "Forgot Password" and am waiting for the recovery email for the last two hours. (Yes, I've checked the spam folder).

Chemi Pharma - 12-8-2019 at 15:45

Quote: Originally posted by camurgo2  
@Chemi Pharma,

I created this secondary account just to let you know I'm currently locked out of my main account. As soon as this issue resolves I'll respond to your U2U.

Explanation: I forgot my password, clicked on "Forgot Password" and am waiting for the recovery email for the last two hours. (Yes, I've checked the spam folder).


No matter at all @Camurgo. We can wait, heh, heh!

Just to know, the classic method to prepare CaS is reducing CASO4 (gipsum) with powdered charcoal in a crucible. Of course this is valuable only for small quantities to be produced in the Lab.

Here's the procedure extracted from PrepChem.Com:

"Preparation of calcium sulfide

Unless the charcoal is already very finely powdered, it should be ground thoroughly in a large porcelain mortar. 48 g of charcoal are mixed with 145 g of gypsum (CaSO4 • 1/2H2O; plaster of Paris) and placed in the clay crucible. The crucible is heat in a gas furnace to between a bright red and a yellow heat for 1.5 hours. At the end of the reaction, the crucible is removed from the furnace and when cold, the contents of the crucible are inspected and there should be no unburned charcoal left. A small sample should dissolve with effervescence in hydrochloric acid and leave no residue more than a slight turbidity.

Synthetic inorganic chemistry, by A. A. Blanchard, 150-151, 1936"

camurgo2 - 12-8-2019 at 16:09

Thank you.

I found an old thread here discussing several methods of synthesizing CaS:

http://www.sciencemadness.org/talk/viewthread.php?tid=1245

I think that, considering my current lab setup, the method you've mentioned is the most doable for me right now.

[Edited on 13-8-2019 by camurgo2]

knowledgevschaos - 17-8-2023 at 21:24

Here is an article explaining how to make phosphorescent calcium sulfide through heating oyster shells. pure calcium carbonate should work for making the pure substance, but oyster shells apparently work better for producing a phosphor.
https://sciencenotes.org/make-glow-dark-powder-oyster-shells...