Electrolysis

Definition of Electrolysis

• A process that produces a non-spontaneous redox reaction by passing an electric current from a power supply through an electrolyte

• Allows for electrical energy to be converted into chemical energy

• Usually used to produce highly reactive substances (strong oxidants and reductants) that would not be naturally found in their native (pure) state

Purpose of the Power Supply

• Acts as an ‘electron pump’

• Withdraws electrons from the anode and forces them into the cathode

• Allows for a non-spontaneous redox reaction to occur

• Allows for a relatively weak oxidant to react with a relatively weak reductant

Purpose of the variable resistor

To maintain a constant current by restricting the flow of current in a cell

Connecting the power supply

• The positive terminal of the power supply should be connected to positively charged electrode (anode)

• The negative terminal of the power supply should be connected to negatively charged electrode (cathode)

• Voltage used should be slightly greater than that produced by the products spontaneously (e.g slightly greater than 1.27V)

Molten electrolytes

• Used when water is a stronger oxidant or reductant than the desired reaactant

• Produced by melting a solid ionic compound

• High temperatures are required to melt the electrolyte and maintain it in a molten state:costly due to large amts of electricity

• Can act to also increase the rate of reaction due to high temp

• Other compounds can be added to reduce the melting point of the electrolyte, as long as they do not participate in the reaction