Q64 / 180 · JIPMER 2017 · Chemistry
In cyamide extraction process of silver from argentite ore, the oxidising and reducing agents are respectively.
- A$\mathrm{O}_2$ and $\mathrm{CO}_2$
- Correct answerB$\mathrm{O}_2$ and Zn dust
- C$\mathrm{HNO}_3$ and Zn dust
- D$\mathrm{HNO}_3$ and CO
Solution
The extraction of silver involves in cyanide process are
(i) $\mathrm{Ag}_2 \mathrm{~S}+2 \mathrm{CN}^{-}+\mathrm{O}_2 \longrightarrow 2\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}+\mathrm{SO}_2$
(ii) $\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}+\mathrm{Zn} \longrightarrow\left[\mathrm{Zn}(\mathrm{CN})_4\right]^{2-}+\mathrm{Ag}$
Thus, in (i) $\mathrm{O}_2$-act as oxidising agent (oxidise sulphide to $\mathrm{SO}_2$ ) and in (ii) Zn act as reducing agent (reduce $\mathrm{Ag}^{+}$to Ag ).
Hence, the correct answer is option: 'B'.