Sodium Sulfite or Sodium sulfate?

For years I have been staring at a repurposed brown, Kodak chemistry jar, filled with a white powder with "Sodium Sulfite" and "NaS03" scrawled on the label. Got the bottle with some darkroom equipment and it's still fully dry, powdery and well sealed, but I don't know what exactly it would be, as NaS03 purports to be "Sodium Sulfate".

Anyone know of a practical test to determine the true identity?

If it is Sodium Sulfate and not Sodium Sulfite, what practical good is it in photo chemistry? I do not ever recall seeing any formula call for Sodium Sulfate.

I would hate to toss pretty much full quart of a good chemical, but unidentified it will have to go to the next hazmat disposal event.

Kino said:

as NaS03

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Sodium sulfite is Na2SO3
Sodium sulfate is Na2SO4

Kino said:

Anyone know of a practical test to determine the true identity?

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Make a solution and test pH. If it's neutral, it's sulfate. If it's alkaline (~pH9), it's sulfite.

Kino said:

I do not ever recall seeing any formula call for Sodium Sulfate.

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I think it's an ingredient in Kodak's ECN2 remjet removal/softening bath.

koraks said:

Sodium sulfite is Na2SO3
Sodium sulfate is Na2SO4


Make a solution and test pH. If it's neutral, it's sulfate. If it's alkaline (~pH9), it's sulfite.


I think it's an ingredient in Kodak's ECN2 remjet removal/softening bath.

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Thank you. Good information.

Sulfate is used in tropical developers, to reduce gelatin swelling.