Video Transcript
The figure describes a generic cell
diagram. The X-term represents one chemical
element. The Y-term represents a different
element. What terms should be put into boxes
one through four? (A) Anode, cathode, oxidation,
oxidation. (B) Anode, cathode, reduction,
oxidation. (C) Anode, anode, oxidation,
reduction. (D) Cathode, cathode, oxidation,
reduction. (E) Anode, cathode, oxidation,
reduction.
In this question, we want to know
what term should be placed in the boxes to correctly label a generic cell
diagram. This notation is called a cell
diagram. It can also be called the cell
notation. We typically use cell diagrams as a
shorthand to write the information about a galvanic cell. A galvanic cell is a type of
electrochemical cell where electrons are generated spontaneously by a redox
reaction. In other words, in a galvanic cell,
chemical energy is converted to electrical energy.
As with all electrochemical cells,
a galvanic cell has both a cathode and an anode. The anode is an electrode which
undergoes oxidation, while a cathode is where reduction occurs. As electrons leave the anode,
oxidizing it, positive ions also leave the anode and go into solution. As electrons from the external
circuit, or wire, enter the cathode, reducing it, positive ions in solution gain
these electrons.
In a generic cell diagram,
information about the galvanic cell is written in a specific place. On the left-hand side, information
about the anode is written. We start by writing the chemical
symbol for the metal electrode. This is followed by a vertical line
that indicates a phase boundary. The symbol and charge of the
matching ion in solution are then written, and the anode half-cell is complete. The salt bridge linking the two
half-cells is represented by the double vertical line.
On the right-hand side, information
regarding the cathode is written. This includes the metal ion in
solution. There is also a vertical line
indicating a phase boundary. Finally, there is the symbol for
the cathode element.
We know that oxidation occurs at
the anode where atoms are converted to positive metal ions as electrons are
lost. And we know that reduction occurs
at the cathode as the metal ions in solution gain electrons and are converted to
neutral atoms. We can see that the correct answers
for the boxes one through four match answer choice (E). So the correct terms for boxes one
to four are (E) anode, cathode, oxidation, reduction.
