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Re: Aquatic Plants Digest V3 #244
Steve Pushak wrote:
> 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?
Yes. Calcium sulfate (CaSO4) is soluble, in cold water, to the extend of
2.4 g/L and CaCO3 = 0.015 g/L.
Solubilitie of other sulfates:
CuSO4 = 143 g/L & CuSO4.5H2O - 316 g/L.
MgSO4 = 260 g/L; MgSO4.7H2O (Epsom salt) = 710 g/L.
MnSO4 = 520 g/L
ZnSO4 = 865 g/L
Compare this to ZnCO3 = 0.01 g/L and CuCO3 = <<0.001 g/L.
Of course, the solubility of all carbonates depends greatly on the pH.
At low pH they tend to exchange the anion and convert to different
salts, which might be more soluble.
At high pH the hydroxides will likely precipitate, except in the case of
calcium, where the solubility of Ca(OH)2 is 1.65 g/L.
Other solubilities are:
Cu(OH)2 = unmeasurable
Fe(OH)2 = 0.0067 g/L; Fe(OH)3 = unmeasurable
Mg(OH)2 = 0.009 g/L
Mn(OH)2 = 0.002 g/L
Zn(OH)2 = 0.000 002 6 g/L
Lead, on the other hand, is comparatively soluble:
PbSO4 = 0.043 g/L &
Pb(OH)2 = 0.155 g/L
PbCO3 = 0.001 g/L; basic lead carbonate = <<0.001 g/L