Question

Complexes formed in the following methods are:

(I) Mond's process for purification of nickel
(II)Removal of lead poisoning from the body
(III) Cyanide process for extraction of silver
(IV) Froth floatation process for separation of $ZnS$ from galena are by using depressant

• A. $Ni\left(CO{)}_4\right[Pb\left(EDTA\right){]}^{2-}\left[Ag\right(CN{)}_2\left]\right[Zn\left(CN{)}_2\right]$
• B. $Ni\left(CO{)}_4\right[Pb\left(EDTA\right){]}^{2-}\left[Ag\right(CN{)}_2{]}^{-}\left[Zn\right(CN{)}_4{]}^{2-}$
• C. $Ni\left(CO{)}_6\right[Pb\left(EDTA\right){]}^{4-}\left[Ag\right(CN{)}_2{]}^{-}\left[Zn\right(CN{)}_6{]}^{4-}$
• D. $Ni\left(CO{)}_4\right[Pb\left(EDTA\right){]}^{2-}\left[Ag\right(CN{)}_4{]}^{3-}\left[Zn\right(CN{)}_4{]}^{2-}$

Answer 1

The correct option is B $Ni\left(CO{)}_4\right[Pb\left(EDTA\right){]}^{2-}\left[Ag\right(CN{)}_2{]}^{-}\left[Zn\right(CN{)}_4{]}^{2-}$

• Mond's Process:
  

$Ni+4CO\uparrow \stackrel{{50}^{\circ }C}{\to }\left[Ni\right(CO{)}_4]\stackrel{{230}^{\circ }}{\to }Ni+4CO\uparrow$
Impure volatile complex pure

• Removal of lead poisoning:
  

$P{b}^{2+}+EDT{A}^{4-}\rightleftharpoons \left[Pb\right(EDTA){]}^{2-}$

• Cyanide process:
  

Silver and gold are extracted by the cyanide process (Mac Arthur - Forrest process). After the preliminary crushing and concentration by froth floatation process, the ore (crushed auriferous rocks in the case of gold) is leached with dilute (0.4 - 7%) solution of sodium cyanide made alkaline by adding lime kept agitated by a current of air. Silver (or gold) pass into solution as argento cyanide (or aurocyanide) :

$A{g}_{2}S+4NaCN\to 2Na\left[Ag\right(CN{)}_2]+N{a}_{2}S$

• Separation of $ZnS$ from $PbS$:
  

$ZnS+C{N}^{-}\rightleftharpoons \left[Zn\right(CN{)}_4{]}^{2-}$