Echem Cells

VOLTAIC CELL (GALVANIC CELL)

An electrochemical cell that uses a spontaneous (product-favored) redox reaction to produce electricity and supply it to an external circuit (a battery)

ELECTROLYSIS CELL (ELECTROLYTIC CELL)

An electrochemical cell that uses electrical energy from an external source to force a nonspontaneous (reactant-favored) redox reaction to occur

SPONTANEOUS REACTION

A reaction that wants to move forward and releases energy; the basis for the production of current in a voltaic cell

NONSPONTANEOUS REACTION

A reaction that does not want to move forward; it requires an external energy input (electricity) to proceed, as in an electrolytic cell

ANODE (GALVANIC CELL)

The negative electrode where oxidation occurs; it is the source of electrons that flow through the external wire

CATHODE (GALVANIC CELL)

The positive electrode where reduction occurs; it is the terminal that receives electrons from the external wire

ANODE (ELECTROLYTIC CELL)

The positive electrode where oxidation occurs; it is connected to the positive terminal of the external power source

CATHODE (ELECTROLYTIC CELL)

The negative electrode where reduction occurs; it is connected to the negative terminal of the external power source

SALT BRIDGE (OR POROUS DISK)

A component that completes the circuit in a galvanic cell by allowing ion flow between the half-cells to maintain charge neutrality

METALLIC CONDUCTION

The flow of electrons through the external wire and the electrodes

IONIC CONDUCTION

The flow of ions through the salt bridge or solution to maintain charge balance

CELL NOTATION

A shorthand representation of an electrochemical cell (e.g., Mg (s) | Mg2+ (aq) || Al3+ (aq) | Al (s)), listing the anode components on the left and cathode components on the right

ELECTROLYSIS

The overall process in an electrolytic cell where electrical energy is used to bring about a nonspontaneous chemical change (e.g., gold-plating a spoon)

FARADAY’S LAW OF ELECTROLYSIS

The amount of substance that undergoes oxidation or reduction at each electrode during electrolysis is directly proportional to the amount of electricity that passes through the cell