Year 12 Chemistry: Electrolysis Flashcards

Summary of key terms, definitions, and chemical principles regarding electrolysis and electrolytic cells as presented in the Year 12 Chemistry lecture.

Electrolysis

The process of using electrical energy to drive a non-spontaneous chemical change by passing an electric current through an electrolyte.

Redox Reactions

Chemical processes involving the transfer of electrons between species, consisting of oxidation and reduction.

Reductant

The species that gives up electrons during a redox reaction and is subsequently oxidised.

Oxidant

The species that gains electrons during a redox reaction and is subsequently reduced.

Spontaneous Reaction

A reaction that proceeds without any external input of energy, occurring when the overall standard cell potential $E^\text{o}$ is positive.

Standard Cell Potential ($E^\text{o}$)

A value measured in volts used to determine spontaneity; if positive, the reaction is spontaneous, and if negative, it is non-spontaneous.

Electrochemical Cell

A system that relies on spontaneous redox reactions to convert chemical energy into a sustained flow of electrical energy through an external circuit.

Non-Spontaneous Reaction

A reaction that will not proceed on its own under standard conditions ($E^\text{o} < 0$) and requires external electrical energy to be driven.

Electrolytic Cell

A setup used to perform electrolysis, consisting of a battery, connecting wires, electrodes, and an electrolyte.

Electrodes

Conductive materials, such as graphite rods, that provide the physical site for oxidation and reduction to occur in a cell.

Electrolyte

A substance, either molten or in aqueous solution, that contains mobile ions allowing it to conduct an electric current.

Graphite

A common material used for electrodes because it is an excellent electrical conductor and is largely chemically inert.

Inert Electrodes

Electrodes that do not participate in the chemical reaction themselves but simply provide a surface for electron transfer.

Current in the Electrolyte

The flow of charge achieved through the migration of positive cations toward the negative electrode and negative anions toward the positive electrode.

Current in the Wire & Electrodes

The movement of negatively charged electrons from the negative terminal of the power source toward the cathode.

Cathode (Electrolytic Cell)

The negative ($-$) electrode where reduction occurs as cations pick up electrons supplied by the external power source.

Anode (Electrolytic Cell)

The positive ($+$) electrode where oxidation occurs as anions surrender electrons to the electrode.

Cathode Reduction Half-Equation (Molten $NaCl$)

$$Na^+(l) + e^- \rightarrow Na(s)$$

Anode Oxidation Half-Equation (Molten $NaCl$)

$$2Cl^-(l) \rightarrow Cl_2(g) + 2e^-$$