Making metal pure

The idea

With impure metal as anode, a thin strip of pure metal as cathode and a metal salt solution as electrolyte, current carries pure metal from anode to cathode; soluble impurities enter the solution and insoluble ones settle as anode mud.

Not pure yet

The metal from a furnace still has impurities mixed in.

What could make it pure?

• Passing an electric current through a salt solution
• Painting it
• Leaving it in the open

The refining cell

Press Next step.

Pure metal moves across

In electrolytic refining the impure metal is the anode and a thin strip of pure metal is the cathode. The electrolyte is a solution of a salt of the metal. The current carries pure metal from the anode to the cathode. Soluble impurities go into the solution. Insoluble impurities settle as anode mud.

With impure metal as anode, a thin strip of pure metal as cathode and a metal salt solution as electrolyte, current carries pure metal from anode to cathode; soluble impurities enter the solution and insoluble ones settle as anode mud.

Notes

Electrolytic refining: impure anode, pure cathode, metal salt solution; soluble impurities dissolve, insoluble ones settle as anode mud.

Check yourself

In electrolytic refining, the impure metal is the ...

What is the electrolyte in electrolytic refining?

Where does the pure metal collect?

What is anode mud?

• cathode. The cathode is the thin strip of pure metal.
• electrolyte. The electrolyte is a solution of a salt of the metal.
• anode — correct. Yes!
• A solution of a salt of the metal — correct. Yes!
• Pure water. The electrolyte is a solution of the metal salt.
• Kerosene oil. The electrolyte is a solution of a salt of the metal, not an oil.
• On the anode. The anode is the impure metal, which dissolves.
• On the cathode — correct. Yes!
• At the bottom as mud. The mud is the insoluble impurity; the pure metal is deposited on the cathode.
• Pure metal that has fallen off. The pure metal goes to the cathode; the mud is made of insoluble impurities.
• Soluble impurities in the solution. Soluble impurities go into the solution; the insoluble ones settle as anode mud.
• Insoluble impurities that settle at the bottom of the anode — correct. Yes!