Using Electrolysis to Extract Metals Flashcards

All 6 cards in this deck

When is electrolysis used to extract a metal instead of reduction with carbon?

When the metal is too reactive to be extracted by reduction with carbon (more reactive than carbon), or if the metal reacts with carbon.

Why is extracting a metal by electrolysis expensive?

Large amounts of energy are needed to melt the compound and to produce the electric current.

What is the electrolyte used in the manufacture of aluminium?

A molten mixture of aluminium oxide and cryolite.

Why is cryolite mixed with the aluminium oxide in aluminium extraction?

It lowers the melting point of the mixture, so less energy (and cost) is needed to melt it.

Why must the carbon positive electrode be continually replaced in aluminium extraction?

The oxygen produced at the anode reacts with the hot carbon to form carbon dioxide, so the electrode wears away.

What is produced at each electrode when molten aluminium oxide is electrolysed?

Aluminium at the negative electrode (cathode) and oxygen at the positive electrode (anode).