Video Transcript
What substance is most likely to be
entering the electrolytic cell at point A? (A) Waste gases, (B) carbon, (C)
molten aluminum, (D) alumina, (E) cryolite.
Aluminum is an incredibly important
metal that is used for a wide range of applications worldwide. But it can be very costly to obtain
pure aluminum. Typically, the most effective
method to obtain pure aluminum is through electrolysis. Electrolysis is a chemical process
caused by passing electricity through an electrolyte. Typically, the process of
electrolysis utilizes a setup that includes an electrolyte solution, a negatively
charged cathode, a positively charged anode, and a power supply. All together these components make
up an electrolytic cell.
In the industrial electrolysis of
aluminum, the equipment is a little more complex than what we are showing here. It’s important to note that in an
industrial electrolytic cell used to extract aluminum, all of the electrodes are
made from carbon. Aluminum oxide, or Al2O3, is added
through an opening at the top of the cell. Aluminum oxide is also known as
alumina. Alumina is mixed with molten
cryolite to form an electrolyte solution in the bottom of the cell.
A large electrical current is run
through the electrolyte solution, breaking the alumina into its constituent
elements. Aluminum ions gain electrons at the
cathode. This reduction of the Al3+ ions
produces liquid aluminum metal. The molten aluminum is then
collected through the port labeled C. The oxide ions from alumina lose
electrons at the anodes. The oxidation of the oxide ions
produces molecules of oxygen that bubble out of the solution and leave the cell
through port B.
So, which substance is most likely
to be entering the electrolytic cell at point A? According to our diagram, alumina
is added to molten cryolite from the port in the top of the cell labeled A. Therefore, the correct answer is
answer choice (D), alumina.
