Question

Extraction of Ag from sulphide ore and removal of unreacted silver bromide from photographic plate involves complexes:
A. ${[Ag{({S_2}{O_3})_2}]^{3 - }}$ in both
B. ${[Ag{(CN)_2}]^ - }$ in both
C. ${[Ag{({S_2}{O_3})_2}]^{3 - }},{[Ag{(CN)_2}]^ - }$
D. ${[Ag{(CN)_2}]^ - },{[Ag{({S_2}{O_3})_2}]^{3 - }}$

Answer 1

Hint:Silver is extracted from its sulphide ore by reacting with sodium cyanide which results in the formation of a complex and in the generation of photographic plate the unreacted silver bromide is washed using sodium thiosulphate solution which results in formation of another complex.

Complete step by step answer:The silver can be extracted from its sulphide ore by cyanide process.
In this process, the concentrated solution of silver sulphide is reacted with a dilute solution of sodium cyanide. A current of air is passed through the solution continuously which after a few hours results in the formation of a soluble complex known as sodium argento cyanide.
The reaction of silver sulfide with sodium cyanide is shown below.
$AgS + 4 NaCN \to 2Na[Ag{(CN)_2}] + N{a_2}S$
In this reaction, one mole of silver sulphide reacts with four mole of sodium cyanide to form two mole of sodium argento cyanide and one mole of sodium sulphide.
In the development of photographic film, quinol is reacted with silver bromide.
The reaction of quinol and silver bromide is shown below.
${C_6}{H_4}{(OH)_2} + 2AgBr \to 2Ag + {C_6}{H_4}{O_2} + 2HBr$
In this reaction, one mole of quinol reacts with two mole of silver bromide to form two mole of silver, one mole of benzoquinone and two mole of hydrogen bromide.
The formation of silver results in the formation of good film.
The excess of silver bromide is washed from the film by adding sodium thiosulfate.
The reaction of silver bromide and sodium thiosulfate is shown below.
$AgBr + 2N{a_2}{S_2}{O_3} \to N{a_3}[Ag{({S_2}{O_3})_2}] + NaBr$
In this reaction silver bromide reacts with sodium thiosulfate to form a complex known as sodium argento thiosulfate and sodium bromide.
Thus, the complexes involved in the extraction of Ag from sulphide ore and removal of unreacted silver bromide from photographic plate are ${[Ag{(CN)_2}]^ - },{[Ag{({S_2}{O_3})_2}]^{3 - }}$.
Therefore, the correct option is D.

Note: Make sure that the complex formed is a sodium complex where sodium is the cation which is common in both the reaction which is excluded in the options and only anions are present.