Untitled - Kelly Walsh High School

Electrochemistry 269
Don’t Forget!
The difference is that the electrons are now flowing through a wire from the oxidation
half-reaction to the reduction half-reaction. The flow of electrons
through a wire is electricity. If we connect a voltmeter to the wire connecting
the two electrodes, we would measure a current of 1.10 V. This galvanic cell is
a Daniell cell.
The electrode at which oxidation is taking place is called the anode and the electrolyte
solution in which it is immersed is called the anode compartment. The
electrode at which reduction takes place is the cathode and its solution is the cathode
compartment. We label the anode with a negative sign (), while the cathode
has a positive sign (). The electrons flow from the anode to the cathode.
Oxidation is an anode process.
Sometimes the half-reaction(s) involved in the cell do not have a solid conductive
part to act as the electrode, so an inert (inactive) electrode, a solid conducting
electrode that does not take part in the redox reaction, is used.
Graphite and platinum are common inert electrodes.
Cell notation is a shorthand notation of representing a galvanic cell. To write
the cell notation for the Daniell cell you:
1. Write the chemical formula of the anode: Zn(s)
2. Draw a single vertical line to represent the phase boundary between the
anode and the anode compartment: Zn(s) |
3. Write the reactive part of the anode compartment with its initial concentration
(if known) in parenthesis (assume 1 M in this case): Zn(s) | Zn2 (1 M)
4. Draw a double vertical line to represent the salt bridge connecting the two
electrode compartments: Zn(s) | Zn2 (1 M) ||
5. Write the reactive part of the cathode compartment with its initial concentration
(if known) shown in parenthesis: Zn(s) | Zn2 (1 M) || Cu2 (1 M)
6. Draw a single vertical line representing the phase boundary between the
cathode compartment and the cathode: Zn(s) | Zn2 (1 M) || Cu2 (1 M) |
7. And finally write the chemical formula of the cathode: Zn(s) | Zn2 (1 M) ||
Cu2 (1M) | Cu(s)