Cyanide industrial uses

Consider the electroplating of copper, an established industrial process. It is well known to the expert in the field that fast plating of thick layers can be achieved in a so-called acid bath, which consists of CuSO in H SO (with some additives, which need not concern us at this point). If, on the other hand, one wishes to obtain a smooth and uniform deposit on an intricately shaped body, an alkaline cyanide bath is better. The alkaline bath consists of copper ions in an excess of KCN (kept at high pH, to prevent the formation of volatile and highly poisonous HCN). In this bath copper exists as the negatively charged complex ion [Cu(CN) ]. Now, we recall that to achieve uniform current... 

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