[pure-silver] Re: sulfite in PMK working solution
- From: Ryuji Suzuki <rs@xxxxxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 28 Dec 2004 16:51:03 -0500 (EST)
This depends on the precise nature of the "sodium bisulfite" used in
the solution. Pure sodium bisulfite in dry form is exceedingly rare
unless you pay a lot of money for analytical reagent grade chemical.
Most are mixture of bisulfite and metabisulfite, or simply
pure metabisulfite sold as bisulfite.
1 mole of bisulfite makes 1 mole of sulfite when pH is adjusted well
above its pK. Similarly, 1 mole of metabisulfite makes 2 moles of
sulfite. (This is because 1 mole of metabisulfite makes 2 moles of
bisulfite when fully dissolved in water.) These are precise.
What is not precise is what the label says and what exactly it is.
--
Ryuji Suzuki
"Keep a good head and always carry a light camera."
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