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solubility of Zinc and Copper (technical)
My old chemistry text (Mortimer) gave the solubility product of some
carbonates as follows:
CaCO3 4.7 * 10**-9
CuCO3 2.5 * 10**-10
ZnCO3 2 * 10**-10
CaSO4 2.4 * 10**-5
No solubility products were given for the sulphate salts. Does that mean
that the sulphate salts of those metals are fairly soluble?
Does this mean that these anions would not precipitate in the presence
of bicarbonate under typical aquarium conditions since calcium remains
dissolved that way?
I don't think that we should say that zinc and copper are not soluble in
the way that iron and manganese are. (referring to Neil's comments on
substrate minerals) These metals, if present, can be toxic to plants and
animals at high enough concentrations.
Copper (and probably other metals) are less toxic if chelated such as by
organic humic complexes from peat. This is one reason why the humic
material in soil or peat helps to prevent possible toxicity problems
with certain kinds of soils.
Sphagnum peat has low enough pH to dissolve aluminum yet we do not see
aluminum toxicity with peat/clay mixtures which contain certain forms of
aluminum. Is it because those aluminum compounds are not chemically
Al(OH)3 has solubility of 5 * 10**-33
Steve Pushak teban at powersonic_bc.anti-spam.ca
Visit "Steve's Aquatic Page" http://home.infinet.net/teban/
for LOTS of pics, tips and links for aquatic gardening!!!
Aquatic Gardeners Association - technical advisor