Question

The formation of complex compounds, finds application in the extraction of some metals. Furnish one example to support the above statement.

Answer 1

1. The formation of complex compounds plays an important role in the extraction of certain metals by increasing their solubility or selectivity during the process.
2. A classic example is the extraction of gold (Au) using cyanide ions (CN⁻). In this method, gold is treated with an aqueous solution of sodium cyanide (NaCN) in the presence of oxygen.
3. Gold forms a soluble complex, [Au(CN)₂]⁻, which can then be separated from the ore: 
   \[\ce{4Au + 8CN^- + O2 + H2O → 4[Au(CN)2]^- + 4OH^-}\]
4. This process is known as cyanidation.
5. Cyanidation allows for the efficient extraction of gold from low-grade ores.
6. This example demonstrates the practical importance of complex formation in metallurgy.