Uses the electric potential between two distinct electrically conducting chemical phases (usually solid-liquid or solid-gas) to generate a current of electrons from one phase to another, *converting chemical energy into electrical energy.
**Spontaneous and positive cell potential!
*Current always flows against electrons and toward the more basic solution (less positive side, less H+).
T = terminals (electronic conductors such as metal wires): must be made of chemically identical forms of matter in order to measure potential.
E = electrodes (also electronic conductors such as ionic solution): Anode (-/oxidation), loses electrons LEO, AN OX. Cathode (+/reduction), Gains electrons GER, RED CAT.
I = IONIC conductor ("salt bridge"): impermeable to electrons, carries current in form of ions when the cell use two different solutions; prevents equilibrium.
-> When cell is formed, the emf is the electric potential difference between T and T' when they are NOT connected.
*Note: solutions used are 1M (std conditions) for use of reductive potentials!
(cell diagram: cathode on right ("reduction on right"), solids outside, single line, solutions inside, double line to represent salt bridge)