Unit 3 Chemistry AOS 2: Production of Chemicals Using Electrolysis

This set of vocabulary flashcards covers the fundamental principles of electrolysis, commercial cell designs, rechargeable batteries, green hydrogen technology, and the application of Faraday's Laws.

Electrolysis

The passing of electrical energy through a conducting source (electrolyte) to cause non-spontaneous redox reactions to occur.

Electrolytic Cell

A device that converts electrical energy into chemical energy through a non-spontaneous redox reaction, requiring an external power supply.

PANIC

A mnemonic for electrolytic cells standing for "Positive is Anode, Negative Is Cathode."

Secondary Cells

Rechargeable cells that discharge as a galvanic cell (converting chemical to electrical energy) and recharge as an electrolytic cell (converting electrical to chemical energy).

Green Hydrogen

Hydrogen produced using renewable energy, such as solar or wind, to electrolyse water, resulting in net zero emissions.

Polymer Electrolyte Membrane (PEM)

A selectively permeable plastic polymer in an electrolyser that allows protons to pass while blocking electrons, water, and gases ($H_2$ and $O_2$).

Artificial Photosynthesis

A system using visible light-absorbing materials and catalysts to convert water and solar energy into hydrogen fuel and oxygen: $2H_2O \rightarrow 2H_2 + O_2$.

Faraday's Constant ($F$)

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

Downs Cell

A commercial electrolytic cell used to produce chlorine gas ($Cl_2$) and sodium metal ($Na$) from molten sodium chloride ($NaCl$).

Hall-Heroult Cell

An industrial cell used to produce aluminium metal ($Al$) by dissolving alumina ($Al_2O_3$) in molten cryolite ($Na_3AlF_6$).

Cryolite

A substance ($Na_3AlF_6$) added to alumina in the Hall-Heroult cell to lower its melting point from approximately $2050^{\circ}\text{C}$ to between $950\text{--}1000^{\circ}\text{C}$, saving energy.

Membrane Cell

A cell used to produce chlorine, hydrogen, and sodium hydroxide from concentrated brine, utilizing a semipermeable membrane to prevent products from mixing.

Electroplating

The process of depositing a layer of or metal onto the surface of another metal via electrolysis, where the object to be plated acts as the cathode.

Anode Mud

A sludge of solid metal impurities, such as silver ($Ag$) and gold ($Au$), that forms beneath the anode during copper refining because they are weaker reductants than copper.

Inert Electrodes

Electrodes, such as graphite or platinum, that facilitate the transfer of electrons but do not take part in the chemical reaction.

Charge Equation ($Q$)

The formula used to calculate electric charge: $Q = I \times t$, where $I$ is current in Amperes ($A$) and $t$ is time in seconds ($s$).

Electrode Polarities (Recharging)

During the recharging of a secondary cell, the anode is the positive terminal and the cathode is the negative terminal.

Strongest Oxidising Agent (Aqueous Electrolysis)

In aqueous solutions, water ($H_2O$) can act as the strongest oxidant if the dissolved metal ions are below it on the electrochemical series.