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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: ace_of_beer on July 19, 2008, 08:36:17 AM

Title: Sulfide oxidation
Post by: ace_of_beer on July 19, 2008, 08:36:17 AM

When adding nitrite and sulfide to an anoxic sterile growth media I see the formation of a yellow color in the media. The color doesn't form immediately.
Does anyone know whether nitrite can react with sulfide and generate a yellow soluble product ?

Title: Re: Sulfide oxidation
Post by: vhpk on July 19, 2008, 10:56:38 PM

Quote from: ace_of_beer on July 19, 2008, 08:36:17 AM

When adding nitrite and sulfide to an anoxic sterile growth media I see the formation of a yellow color in the media. The color doesn't form immediately.
Does anyone know whether nitrite can react with sulfide and generate a yellow soluble product ?

Show your attempt first, write the equation representing the process which you think? Do you have any predictions about the product of the reaction above?

Title: Re: Sulfide oxidation
Post by: ace_of_beer on July 20, 2008, 10:17:02 AM

Well what I think what might happend is a reaction between nitrite and sulfide leading to the formation of elementary sulfur: H₂S / HS^-  +  NO₂^-  -->  S⁰ + N₂  + H₂O
The elementary sulfur would result in a yellow color but as far as I know elementary sulfur is insoluble in water and I don’t observe any precipitation.

Alternatively nitrite could be reduced to ammonium. The ammonium could then react with sulfide producing ammonium sulfide. H₂S / HS^-  + NH₄⁺  -->  [NH₄]₂S
Ammonium sulfide is yellow and is extremely soluble in water. However, when nitrite is replaced by ammonium no yellow color occurs.