Question

The cyanide process of gold extraction involves leaching out gold from its ore with $CN^-$ in the presence of Q in water to form R. Subsequently, R is treated with T to obtain Au and Z. Choose the correct option(s)

• A. Q is O$_2$
• B. T is Zn
• C. Z is $[Zn(CN)_4]^{2-}$
• D. R is $[Au(CN)_4]^-$

Answer 1

Answer: (C)

Z is $[Zn(CN)_4]^{2-}$

Answer 2

${4Au(s) + 8CN^{-}(aq) + 2H2O(aq) +}$ $\underset{\text{(Q)}}{{O2(g)}}$ ${->4[Au(CN)2]^{-}(aq) + 4OH^{-}(aq)}$
$\underset{\text{(R)}}{{2[Au(CN)2]^{-}}}$ ${(aq) +}$ $\underset{\text{(T)}}{{Zn(s)}}$ $\underset{\text{(Z)}}{{{->}{[Zn (CN)4]^{2-}}}}$ ${(aq) + 2Au(s)}$