Interesting, Ian. So if the local water treatment plant says cyanide in effluent must be below 3ppm, do I conclude it must be below that because it is bound to the iron molecule and not free? That would be an awesome result.
That rule applies only to cyanide itself, which is a very toxic chemical. When you bond another atom or another molecule to an existing molecule, you COMPLETELY change its chemical properties. It's toxicity changes, its appearance changes, its reactivity changes, etc.
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