Question

Silver can be separated from lead by:

• A. fractional crystallization
• B. amalgamation
• C. cupellation
• D. addition of zinc

Answer 1

The correct option is D addition of zinc

The Parkes process is a pyrometallurgical industrial process for removing silver from lead during the production of bullion. It is an example of liquid–liquid extraction.

The process takes advantage of two liquid-state properties of zinc. The first is that zinc is immiscible with lead, and the other is that silver is 3000 times more soluble in zinc than it is in lead. When zinc is added to liquid lead that contains silver as a contaminant, the silver preferentially migrates into the zinc. Because the zinc is immiscible in the lead it remains in a separate layer and is easily removed.