Unit 3 Chemistry: Production of Chemicals Using Electrolysis Flashcards

A comprehensive set of vocabulary flashcards covering the principles of electrolysis, commercial electrolytic cells, green energy innovations, and Faraday's Laws as per the Unit 3 VCE Chemistry curriculum.

Electrolysis

The passing of electrical energy through a conducting source (electrolyte) to cause non-spontaneous redox reactions ($\text{Electrical energy} \rightarrow \text{Chemical energy}$).

Electrolytic Cell

A device consisting of an electrolyte, two electrodes, and a power supply used to drive non-spontaneous redox reactions.

Anode (Electrolytic Cell)

The positive ($+$) electrode where oxidation occurs; electrons are withdrawn from this electrode by the power supply.

Cathode (Electrolytic Cell)

The negative ($-$) electrode where reduction occurs; electrons are supplied to this electrode by the power supply.

Molten Electrolyte

A salt in a liquid state ($l$) used in electrolysis when water would be preferentially reduced or oxidized; requires high temperatures.

Aqueous Electrolyte

A solution where the electrolyte is dissolved in water ($aq$), meaning water ($H_2O$) can potentially act as the strongest oxidant or reductant.

Strongest Oxidising Agent (SOA)

The species highest on the left side of the electrochemical series that is present in the cell; in electrolysis, it is reduced at the cathode.

Strongest Reducing Agent (SRA)

The species lowest on the right side of the electrochemical series that is present in the cell; in electrolysis, it is oxidized at the anode.

Downs Cell

A commercial electrolytic cell used to produce sodium metal and chlorine gas from molten sodium chloride with a calcium chloride additive to lower the melting point.

Hall-Heroult Cell (Hall Cell)

An industrial electrolytic cell where alumina ($Al_2O_3$) is dissolved in molten cryolite ($Na_3AlF_6$) to produce aluminium metal at the carbon cathode.

Cryolite

A compound ($Na_3AlF_6$) used in the Hall cell to lower the melting point of alumina, thereby saving energy in the production of aluminium.

Membrane Cell

A modern electrolytic cell used to produce chlorine gas, hydrogen gas, and sodium hydroxide using a semi-permeable membrane to separate the products.

Secondary Cell

A rechargeable cell that acts as a galvanic cell during discharge and an electrolytic cell during recharge.

Discharging

The process in a secondary cell where chemical energy is converted to electrical energy (acting as a galvanic cell).

Recharging

The process in a secondary cell where electrical energy is converted to chemical energy to reverse the cell reaction (acting as an electrolytic cell).

Green Hydrogen

Hydrogen produced with zero emissions by using renewable energy (solar or wind) to electrolyse water.

Polymer Electrolyte Membrane (PEM)

A selectively permeable membrane in an electrolyser that allows protons ($H^+$) to pass but blocks electrons and gases like $H_2$ and $O_2$.

Artificial Photosynthesis

A technology using semiconductor materials and catalysts to mimic natural photosynthesis, splitting water into hydrogen fuel and oxygen using solar energy.

Electroplating

A process where electrolysis is used to deposit a thin layer of a desired metal onto the surface of another object at the cathode.

Electrorefining

An electrolytic process used to purify metals, such as copper, where the impure metal is the anode and pure metal is deposited on the cathode.

Anode Mud (Sludge)

Solid metal impurities (like gold, silver, or platinum) that fall below the anode during the electrorefining of copper because they are less reactive than copper.

Faraday's Constant ($F$)

The magnitude of electric charge per mole of electrons, approximately equal to $96500\text{ C mol}^{-1}$.

Electrical Charge ($Q$)

The quantity of electricity measured in Coulombs ($C$), calculated as current ($I$) multiplied by time ($t$) in seconds ($Q = I \times t$).