From: Sandy King (sanking@hubcap.clemson.edu)
Date: 05/31/00-08:24:21 AM Z
Richard Knoppow wrote:
>
> Since you are lucky enough to have a copy of Haist (he said with
>his tongue hanging out) does he say anything else, like giving a
>hint about what sort of formulas the Potassium form is not good
>with? Since Sodium Carbonate shows up in three forms in formulas it
>would be useful to know to which he is refering. Some very old
>formulas specify cryataline carbonate, most later ones specify
>either anhydrous or monohydrated.
> Kodak, in their 1930's book on motion picture laboratory technique
>recommends the potassium type _because_ it is delequescent and if
>spilled will stick to whatever it falls on and not blow around. The
>delequescense is a problem with the crystaline form of the sodium
>variety. The advantage of monohydrated sodium carbonate is that is
>is very stable. Potassium carbonate evidently does not store well.
>
No, Haist does not give any hint (at least so far as I have found)
regarding possible incompatibilities of potassium carbonate with
specific formulas. He does point out, as you allude to above, that
potassium carbonate absorbs water from the air very readily, becoming
moist and thus preventing carbonate dust from floating in the air. I
have personally observed this quality in my use of potassium
carbonate, and it presents a real problem in accurate weighing of the
chemical. In certain circumstances I have noted that the actual
weight of the chemical per volume has varied from 1-3X depending on
water absorption.
Sandy King
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