Rapid fixers - chloride X sulphate

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Jorge Omar - 04 Feb 2004 18:24 GMT

Hello,

Thre are rapid fixers made by mixing hypo with ammonium chloride or
sulphate (Kodak's F-7 and F-9).

It just happens that Kodak F-7 uses 50g of chloride, F-9 uses 60g of
sulphate.

The molecular weight of chloride is 53.49g and of sulphate is 132.14g.

Doesn't it looks like there is too little sulphate in F-9?

Thanks,

Jorge

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Jean-David Beyer - 04 Feb 2004 19:24 GMT

> Hello,
>
[quoted text clipped - 8 lines]
>
> Doesn't it looks like there is too little sulphate in F-9?

Sulphate is not what matters; it is the ammonium ions that count. There
is only one ammonium ion in amminium chloride, whereas there are two in
ammonium sulphate.

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Jorge Omar - 04 Feb 2004 21:48 GMT

Thanks, Jean-David.
I've almost forgotten my chemistry classes; taking the 2 NH4 in account
they are very much equivalent.

Jorge

> > Hello,
> >
[quoted text clipped - 12 lines]
> is only one ammonium ion in amminium chloride, whereas there are two in
> ammonium sulphate.

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