Question

Describe the role of the following:
(a) $NaCN$ in the extraction of Silver from Silver ore.
(b) Iodine in the refining of titanium.
(c) Acryolite in the metallurgy of Aluminum.

Answer 1

a) $NaCN$ in the extraction of silver is used as a complexing agent as well as leaching agent.

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

b) Iodine reacts with Titanium to form volatile compound which on further heating decomposes to pure titanium. $Ti\left(impure\right)+2I_2+Heat\stackrel{523K}{\to }Ti{I}_4$

$Ti{I}_4+Heat\stackrel{1700K}{\to }Ti\left(Impure\right)+2I_2$

c) Role of cryolyte is:

i) To decrease the melting point of the mixture from $2323K$ to $1140K$

ii) To increase the electrical conductivity of $A{l}_2{O}_3$