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Chemistry 101

Having commented earlier on Steve's chemistry problems, I got to 
thinking about some of my own blunders that may help others. It 
mainly deals with the solubilities of the common macro chemicals 
we use with our plants. I remember weighing out a good amount of 
K2SO4 and trying to dissolve it in 100ml of water and had a time 
with it not dissolving, eventually dumping it out and starting over. 
This is not a good thing, since we only get limited amounts of 
chemicals and wasting them is not an option. I looked up the sol. 
constants for my chemicals and everything works great now. I 
thought I'd pass it on. Remember, the number of grams is the 
theoretical limit and it's always good to back down a few grams to 
make sure everything does dissolve, or even to a whole number, 
which makes calculating a lot easier. All solubilities are @ 25C.

CaCL2 - freely sol in water, very exothermic.(I use a 50% solution).

MgCl2 - freely sol in water, exothermic, pH~7.(I use 30%)

KCl - 35.7g/100ml water pH~7.

CaCO3 - practically insol in water, sol in dilute acids(Carbonated 
water is acidic if the kH values are low, thus dissolving small 
amounts of CaCO3).

KNO3 - 35.7g/100ml (same as KCl), endothermic rxn, pH = 7.

K2SO4 - 12.0g/100ml, pH = 7 (10g/100ml takes forever to dissolve, 
so 12g/100ml would drive you mad, believe me!)

MgSO4 - (Epson salt) -sol in water @ 20C 71g/100ml, pH~6-7.

Jamie, enjoying the Indian Summer.