Question

(Ag+Pb) alloy $\underset{Zincisadded}{\overset{Meltand}{\to }}(Ag+Pb+Zn)melt\stackrel{Cool}{\to }\underset{LayerY}{\overset{LayerX}{\to }}$

Select the correct statement based on the above scheme :

• A. Layer X contains Zn and Ag
• B. Layer Y contains Pb and Ag but amount of silver in this layer is smaller than in layer X
• C. X and Y are immiscilbe layer
• D. All the correct statements

Answer 1

The correct option is D All the correct statements

(Ag+Pb) alloy $\underset{Zincisadded}{\overset{Meltand}{\to }}(Ag+Pb+Zn)melt\stackrel{Cool}{\to }\underset{LayerY}{\overset{LayerX}{\to }}$

This is Parke's process and it is used for the desilverization of argentiferous lead (PbS + 0.01 to 1 % Ag). It is based on distribution principle, where molten zinc and molten lead form a two phase system. Silver is more soluble in molten zinc than the molten lead.

The Zn - Ag alloy is lighter than Pb and freezes fast. Hence it forms upper layer (X). The floating solidified Zn - Ag alloy can be easily removed from molten Pb.

The lower layer (Y) contains smal amounts of Ag in Pb

From Zn - Ag alloy, zinc is separated by distillation.

So all statements are correct.