So far,
Loss of electron(s) is oxidation while the gain of electron(s) is reduction.
Reducing agent: a substance that loses or gives up electrons to another substance in a
redox reaction.
Oxidizing agent: a substance that gains or removes electrons from another substance in a
redox reaction.
Redox Table: Organizes metals in either increasing reactivity as an oxidizing agent or
decreasing reactivity as a reducing agent.
Pneumonics:
LEO the lion says GER –
LEO: loss of electrons is oxidation
GER: gain of electrons is reduction
“An Ox and Red Cat” –
An Ox: Anode involves Oxidation
Red Cat: REDuction involves CAThode
The set up of an electrochemical cell is A B C –
A: Anode
B: Bridge
C: Cathode
ELECTROCHEMICAL CELLS (VOLTAIC)
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In cells of this type, spontaneous chemical change produces a flow of electricity.
Oxidation occurs at the anode (attracts anion - )
Reduction occurs at the cathode (attracts the cation + )
Electron flow is always from the anode (-) to the cathode (+).
An electric cell must have the following: 2 electrodes (solid conductor), an electrolyte
(aqueous conductor) and a salt bridge (contains electrolyte as well).
 Electron flow can be measured in terms of voltage and current.
Example:
Cell Notation:
Note: The substance with the lowest oxidation state is written closest to the electrode
Standard Cell Potential (E)
 The E, the nought stands for standard conditions: 25C and 101.3 kPa, 1.0 mol/L
 Half-cell reduction potentials (voltages) can be determined by comparing them to the
half potential for hydrogen half-cell.
2H+1 + 2eH2
E = 0.00V (arbitrary choice)
 A reaction is only spontaneous if the oxidizing agent is above the reducing agent in
the Redox table. Using the electric potential values, if adding the two half-cells gives
a positive value than the reaction is spontaneous as written.
Consider the electrochemical cell example above:
Example 2: Draw and label an electrochemical cell using Al/Al+3//Ni/Ni+2