Question

$(Ag+Pb)alloy\underset{isadded}{\overset{meltandzinc}{\to }}(Ag+Pb+Zn)melt\stackrel{Cool}{\to }\frac{Layerx}{Layery}$
Select the correct statement(s) based on above scheme:

• A. Layer X contains zinc and silver
• B. Layer Y contains lead and silver but amount of silver in this layer is smaller than in the layer X.
• C. X and Yare immiscible layers
• D. X and Yare miscible layers

Answer 1

Answer: (A), (B), (C)

The correct options are
A Layer X contains zinc and silver
B Layer Y contains lead and silver but amount of silver in this layer is smaller than in the layer X.
C X and Yare immiscible layers

Parke's process is used for the desilverization of argentiferous lead (PbS + 0.01 to 1 % Ag) and is based on distribution principle as molten zinc and molten lead form a two phase system. Silver is more soluble in molten zinc than in molten lead. The Zn - Ag alloy is lighter and hence forms the top layer (layer X). The Pb - Ag alloy is heavier and forms the bottom layer (layer Y). The two layers are immiscible and hence the floating solidified Zn - Ag alloy can be easily removed from molten Pb.