Solveeit Logo
Login

Question

Chemistry Question on Classical Idea Of Redox Reactions – Oxidation And Reduction Reactions

Statement-I : Leaching of gold with cyanide ion in absence of air/O2 leads to cyano complex of Au(III).
Statement-II : Zinc is oxidized during the displacement reaction carried out for gold extraction.
In the light of the above statements, choose the correct answer from the options given below.

A

Both statement-I and statement-II are correct

B

Both statement-I and statement-II are incorrect

C

Statement-I is correct but statement-II is incorrect

D

Statement-I is incorrect but statement-II is correct

Answer

Statement-I is incorrect but statement-II is correct

Explanation

Solution

Leaching of gold with cyanide ion is done in presence of air/O2air/O_2 leading to cyano complex [Au(CN)2]–[Au(CN)_2]^– where AuAu is in +1+1 oxidation state.

4Au(s)+8CN−(aq)+2H2O(aq)+O2(g)⟶4[Au(CN)2]ag−+4OH−4Au(s)+8CN^−(aq)+2H_2O(aq)+O_2(g)⟶4[Au(CN)_2]_{ag} ^− +4OH^−

2[Au(CN)2]aq−+Zn(s)⟶[Zn(CN)4]aq2−+2Au(s)2[Au(CN)_2]_{aq} ^− + Zn(s)⟶[Zn(CN)_4]_{aq} ^{2−} + 2Au(s)

Zinc is oxidised from (0) to +2 oxidation state during displacement reaction carried out for gold extraction.