Electrochemistry and Chemical Metallurgy

Flashcards covering vocabulary and core concepts from Chapter 3 on Electrochemistry and Chemical Metallurgy, including redox principles, types of cells, conductivities, and battery types.

Electrochemistry

The branch of science which deals with the relationship between electrical energy and chemical energy and the inter-conversion of one form into other.

Electrochemical engineering

The branch of engineering which studies the principles of electrochemistry and their applications in industries.

Electrochemical changes

Chemical changes that involve electron transfer from one chemical species to another.

Reducing agent

A chemical species that loses electrons during a chemical reaction and is subsequently oxidized.

Oxidizing agent

A chemical species that gains electrons during a chemical reaction and is subsequently reduced.

Oxidation

A chemical reaction in which a chemical species loses electrons.

Reduction

A chemical reaction in which a chemical species gains electrons.

Redox reactions

Chemical reactions in which the oxidizing agent is reduced and the reducing agent is oxidized simultaneously.

Half-reaction

One of two parts of an oxidation-reduction reaction, involving either the loss of electrons or the gain of electrons.

Oxido-reduction couple

The oxidation form and reducing form of a chemical species, denoted as Ox/Red.

Oxidation number

The actual charge of an atom if it exists as a monatomic ion, or a hypothetical charge assigned to an atom in a substance.

Electrochemical cell

A device capable of either generating electrical energy from chemical reactions or facilitating chemical reactions through the introduction of electrical energy.

Voltaic cell

Explicitly also called a galvanic cell, it is an electrochemical cell that derives electrical energy from spontaneous redox reactions.

Electrolytic cell

An electrochemical cell in which an electric current drives an otherwise nonspontaneous reaction.

Electrode

The interface between a solid conductor and an ionic conductor where electrons are exchanged.

Anode

The electrode in an electrochemical cell where oxidation occurs.

Cathode

The electrode in an electrochemical cell where reduction takes place.

Metallic conductor

A material that allows electricity to pass through without undergoing chemical change, with flow due to electrons.

Electrolyte

An ionic or electrolytic conductor that allows electricity to pass through in molten states or aqueous solutions due to the movement of ions.

Ohm’s law

States that the electric current flowing across a conductor is directly proportional to the potential difference across it ($V = IR$).

Cell constant

The ratio of the distance between two electrodes to the area of the electrode, represented as $\frac{l}{a}$.

Conductance ($G$)

The reciprocal of resistance ($G = \frac{1}{R}$), measuring the ease with which current flows through an electrolyte.

Specific conductance

Also known as conductivity, it is the reciprocal of resistivity, denoted by the Greek letter kappa ($\kappa$).

Equivalent conductivity ($\Lambda$)

The conductance of all ions produced by 1 gram equivalent of an electrolyte, given by $\Lambda = \kappa \times V$.

Molar conductivity ($\Lambda_m$)

The conducting power of all ions produced by dissolving 1 gmole of an electrolyte in solution.

Salt bridge

An inverted U-tube containing an electrolyte in a viscous medium used to ensure electroneutrality and complete the cell circuit.

Daniel cell

A voltaic cell consisting of zinc and copper electrodes dipped in their respective sulphate solutions.

Cell potential

The driving force for the cell reaction arising from the difference in the tendency of two ions to get reduced, also known as electromotive force (emf).

Nernst equation

An equation used to calculate the electromotive force of a cell: $E = E^o - \frac{RT}{nF} \ln K$.

Standard Hydrogen Electrode (SHE)

A reference electrode arbitrarily chosen to have a standard potential of zero, denoted as $Pt / H(aq)^+ / H_2(g)$.

Electrochemical series

The arrangement of elements in decreasing order of their standard reduction potentials, used to predict the strength of oxidizing and reducing agents.

Active metals

Metals with relatively lower standard reduction potentials.

Noble metals

Metals with relatively higher or less negative standard reduction potentials.

Battery

A power source in which several galvanic cells are connected in series or in parallel.

Primary batteries

Batteries in which the cell reaction is irreversible and get discharged and cannot be used again once reactants are converted.

Secondary batteries

Rechargeable batteries in which the cell reaction is reversible by applying external potential.

Reserve batteries

Batteries which remain inactive until activated immediately before use by adding a missing component like an electrolyte.

Fuel cell

Energy converters that take chemical substances from an external source and convert them to electrical energy.

Electrolysis

The process of passing an electric current through an ionic solution or molten salt to produce a chemical reaction.

Faraday’s first law

States that the mass of a substance produced during electrolysis is proportional to the quantity of electricity passed ($Q = It$).

Faraday’s second law

States that the mass of a substance dissolved or deposited is proportional to the electrochemical equivalent mass (EEM) of the substance.

Electroplating

The process of deposition of a metal on a substrate by passing electric current through an electrolytic solution containing soluble salt of the coating metal.

Concentration cell

A voltaic cell using electrodes of the same metal where the potential difference is derived from differences in concentration in the half-cells.

Chemical metallurgy

The science and technology of extracting metals from their ores, refining them, and preparing them for end use.

Pyrometallurgy

The use of high-temperature reactions and processes for the extraction and refining of metals.

Hydrometallurgy

The production of metal or pure compounds with the help of reactions in aqueous and organic solutions.

Electrometallurgy

The production of pure metal using an electrolytic cell.