Copper isn't that toxic; it's not like lead, mercury or cadmium and as far as I'm aware it's not even classified as a heavy metal.
It is classified as a heavy metal, and is toxic. Same goes for iron. Hence the 'harmful' warning on copper sulphate. Copper is a heavy enough element to bind to and denature proteins, so it produces toxic heavy metal effects. For example copper sulphate is deemed harmful, and can have toxic effects in relatively small doses as it differentiates into copper ions and sulphate ions. Wikipedia suggests that the LD50 for copper sulphate is approximately 300mg/kg, i.e. that 300mg per kg of body weight is enough to kill 50% of test subjects. Compare that to cadmium sulphate with an approximate LD50 of 280mg/kg, or lead sulphate, which also has an LD50 of 300mg/kg. I believe the primary reason that lead is considered more dangerous that copper is that in a metallic state, lead will dissolve in water and produce ions much more readily than copper or most other metals. As for mercury, it's highly volatile.
Anyway, biochemistry rant over
Hero999 said:
That's normal, it absorbs water.
I expected that since it is quite important that they remain in dry granular form, measures would have been taken to remove as much of the moisture from inside the bag as possible. The bag was still sealed when it turned to a congealed slop.
I did throw out the ferric chloride; a big congealed slop seemed little use. I'm still getting into electronics so I would probably only need to use the etchant solution at far apart intervals, so even if I made the whole pack into a solution for later use, I believe the website suggests it'll only be good for a couple of days in that form. I'd probably only get one use out of it.
Hero999 said:
No, it smells like bleach.
I believe bleach smell is usually caused by chlorine or a chlorine compound; but since you're using sodium persulphate rather than ferric chloride, I don't know how you managed that. Ammonia smell is also often associated with bleach, but again I don't see any reason for the formation of ammonia.