Extraction of Metals - Result Question 25
####25. Native silver metal forms a water soluble complex with a dilute aqueous solution of $NaCN$ in the presence of
(a) nitrogen
(b) oxygen
(c) carbon dioxide
(d) argon
$(2008,3 M)$
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Solution:
- A water soluble complex with silver and dilute aqueous solution of $NaCN$ is $Na\left[Ag(CN) _2\right]$. In the cyanide process, the native silver is crushed and treated with aqueous $NaCN$ solution and aerated.
$$ 4 Ag+8 NaCN+2 H _2 O+O _2 \longrightarrow 4 Na\left[Ag(CN) _2\right] $$
$$ +4 NaOH $$
