ELECTROCHEMISTRY GLOSSARY
Ampere (A):
The SI unit for electric current. 1A = 1 C/s (one Coulomb per second).
Anode:
The electrode where oxidation occurs.
Anion:
A negatively charged ion, i.e., one that would be attracted to the anode in electrolysis.
Battery:
A group of two or more galvanic cells connected in series.
Cathode:
The electrode where reduction occurs.
Cathodic Protection:
A form of corrosion prevention in which electrons are continually supplied to the metal that is being protected, making the metal a cathode.
Cation:
A positively charged ion, i.e., one that would be attracted to the cathode in electrolysis.
Cell:
A system in which two connected electrodes are in contact with an electrolyte.
Cell Potential:
The electric potential difference (voltage) between the two half-cells in a galvanic cell.
Chloralkali Process:
It is is a process used to create sodium hydroxide, chlorine, and hydrogen from sodium chloride and water, which is fueled by electrolysis. It is normally conducted in a tank separated by a membrane, although there are other methods, such as using mercury. If potassium chloride or calcium chloride is used instead, potassium hydroxide and calcium hydroxide are produced. When the membrane is not in place, hypochlorites are formed. If it is heated, chlorates are formed.
Coulomb (C):
The SI unit of electric charge, equal to the quantity of electricity conveyed in one second by a current of one ampere.
Corrosion:
The deterioration of a metal by a redox reaction.
Electric Current:
The rate of flow of charge past a point.
Electric Potential Difference (voltage):
The potential energy difference per unit charge.
Electrochemical Cell:
A general term that is used to refer to both a galvanic and an electrolytic cell.
Electrode:
A solid electrical conductor.
Electrolytic Cell:
A Cell that uses electrical energy to produce a chemical change that would not occur spontaneously.
Electrolyte:
An aqueous electrical conductor.
Electrolysis:
The application of current through a cell to produce a chemical change.
Electroplating:
It is a process that uses electrical current to reduce dissolved metal cations so that they form a coherent metal coating on an electrode.
Electrorefining:
It is a method for purifying a metal using electrolysis. An electric current is passed between a sample of the impure metal and a cathode when both are immersed in a solution that contains cations of the metal. Metal is stripped off the impure sample and deposited in pure form on the cathode.
Fuel Cell:
A galvanic cell for which the reactants are continuously supplied.
Galvanic Cell:
An arrangement of two connected half-cells that spontaneously produces electric current.
Galvanizing:
Or galvanization, it is the process in which steel is coated with a thin layer of zinc to protect the steel from corrosion.
Half-Cell:
An electrode and an electrolyte that from half of a complete cell.
Half-reaction Equation Method:
A method for balancing redox equations. This method assumes the reaction occurs in aqueous, acidic solution where H2O and H+ are plentiful. If the reaction occurs in a basic solution, this method allows for a correction at the end.
Hall-Heroult Process:
It is the major industrial process for the production of aluminum. It involves dissolving alumina in molten cryolite, and electrolyzing he molten salt bath to obtain pure aluminum metal.
Impressed Current:
A form of cathodic protection in which electrons from a DC power source are pumped into the metal that is being protected.
Joule (J):
The SI unit of work and energy.
Line Notation:
An abbreviated way to describe cells.
Oxidation:
The process in which one or more electrons is lost by a chemical entity.
Oxidation-reduction (redox) Reaction:
The reaction in which one or more electrons are transferred between chemical entities.
Oxidation Agent:
The reactant that is oxidized (gains or removes electrons from another substance) during an oxidation-reduction reaction.
Oxidation Number:
A number used to keep track of electrons in oxidation-reduction reactions according to certain rules.
Oxidation Number Method:
Also called “Oxidation State method”, it is a method that provides a relatively easy way to balance redox (including ionic redox) equations. The underline principle is that the gain in the oxidation number (number of electrons) in one reactant must equal to the loss in the oxidation number of the other reactant (this is referred to as the conservation of electrons).
Oxidation State:
Also known as oxidation number.
Primary Cell:
A cell that cannot be recharged.
Redox Spontaneity Rule:
A spontaneous redox reaction occurs only if the oxidizing agent (OA) is above the reducing agent (RA) in a table of relative strenthgs of oxidizing and reducing agents.
Redox Table:
A table listing standard reduction potentials of common oxidizing agents and reducing agents in order from strongest to weakest. Also known as a standard potential table.
Reducing Agent:
The reactant that is oxidized (loses or gives up electrons to another substance) during an oxidation-reduction reaction.
Reduction:
The process in which one or more electrons is gained by a chemical entity.
Sacrificial Anode:
A form of cathodic protection in which the oxidation of a more active metal is attached to the steel prevents the iron in the steel from being oxidized.
Salt Bridge:
A tube that contains an electrolyte solution and connects the two half-cells in a galvanic cell.
Secondary Cell:
A cell that can be recharged by being attached to an external source of electrical energy; recharging reverses the chemical reaction that generates the electrical energy.
Single Displacement Reaction:
Also called single-replacement reaction, is a type of oxidation-reduction chemical reaction when an element or ion moves out of one compound and into another. That is, another in a compound replaces one element. This is represented by the general reaction scheme: A + BC → AC + B.
Standard Cell:
A galvanic cell in which all the entities involved in the half-cell reactions are at SATP and the solutions have a concentration of 1.0 mol/L.
Standard Cell Potential (ΔE0r(cell)):
The electric potential difference of a galvanic cell that is operating under standard conditions.
Standard Hydrogen Half-Cell:
The galvanic cell from which all the half-cell potentials are determined; E0r = 0 V (by definition).
Standard Reduction Potential (E0r):
The ability of a half-cell to attract electrons in a cell that is operating under standard conditions.
Volt (V):
The SI unit of a galvanic cell, the SI unit for electric potential. Its unit symbol is V, where 1 V is equal to Joules per Coulomb, or J/C.
Voltaic Cell:
Also known as a galvanic cell.
Voltmeter:
An instrument for measuring electric potential in volts.
The SI unit for electric current. 1A = 1 C/s (one Coulomb per second).
Anode:
The electrode where oxidation occurs.
Anion:
A negatively charged ion, i.e., one that would be attracted to the anode in electrolysis.
Battery:
A group of two or more galvanic cells connected in series.
Cathode:
The electrode where reduction occurs.
Cathodic Protection:
A form of corrosion prevention in which electrons are continually supplied to the metal that is being protected, making the metal a cathode.
Cation:
A positively charged ion, i.e., one that would be attracted to the cathode in electrolysis.
Cell:
A system in which two connected electrodes are in contact with an electrolyte.
Cell Potential:
The electric potential difference (voltage) between the two half-cells in a galvanic cell.
Chloralkali Process:
It is is a process used to create sodium hydroxide, chlorine, and hydrogen from sodium chloride and water, which is fueled by electrolysis. It is normally conducted in a tank separated by a membrane, although there are other methods, such as using mercury. If potassium chloride or calcium chloride is used instead, potassium hydroxide and calcium hydroxide are produced. When the membrane is not in place, hypochlorites are formed. If it is heated, chlorates are formed.
Coulomb (C):
The SI unit of electric charge, equal to the quantity of electricity conveyed in one second by a current of one ampere.
Corrosion:
The deterioration of a metal by a redox reaction.
Electric Current:
The rate of flow of charge past a point.
Electric Potential Difference (voltage):
The potential energy difference per unit charge.
Electrochemical Cell:
A general term that is used to refer to both a galvanic and an electrolytic cell.
Electrode:
A solid electrical conductor.
Electrolytic Cell:
A Cell that uses electrical energy to produce a chemical change that would not occur spontaneously.
Electrolyte:
An aqueous electrical conductor.
Electrolysis:
The application of current through a cell to produce a chemical change.
Electroplating:
It is a process that uses electrical current to reduce dissolved metal cations so that they form a coherent metal coating on an electrode.
Electrorefining:
It is a method for purifying a metal using electrolysis. An electric current is passed between a sample of the impure metal and a cathode when both are immersed in a solution that contains cations of the metal. Metal is stripped off the impure sample and deposited in pure form on the cathode.
Fuel Cell:
A galvanic cell for which the reactants are continuously supplied.
Galvanic Cell:
An arrangement of two connected half-cells that spontaneously produces electric current.
Galvanizing:
Or galvanization, it is the process in which steel is coated with a thin layer of zinc to protect the steel from corrosion.
Half-Cell:
An electrode and an electrolyte that from half of a complete cell.
Half-reaction Equation Method:
A method for balancing redox equations. This method assumes the reaction occurs in aqueous, acidic solution where H2O and H+ are plentiful. If the reaction occurs in a basic solution, this method allows for a correction at the end.
Hall-Heroult Process:
It is the major industrial process for the production of aluminum. It involves dissolving alumina in molten cryolite, and electrolyzing he molten salt bath to obtain pure aluminum metal.
Impressed Current:
A form of cathodic protection in which electrons from a DC power source are pumped into the metal that is being protected.
Joule (J):
The SI unit of work and energy.
Line Notation:
An abbreviated way to describe cells.
Oxidation:
The process in which one or more electrons is lost by a chemical entity.
Oxidation-reduction (redox) Reaction:
The reaction in which one or more electrons are transferred between chemical entities.
Oxidation Agent:
The reactant that is oxidized (gains or removes electrons from another substance) during an oxidation-reduction reaction.
Oxidation Number:
A number used to keep track of electrons in oxidation-reduction reactions according to certain rules.
Oxidation Number Method:
Also called “Oxidation State method”, it is a method that provides a relatively easy way to balance redox (including ionic redox) equations. The underline principle is that the gain in the oxidation number (number of electrons) in one reactant must equal to the loss in the oxidation number of the other reactant (this is referred to as the conservation of electrons).
Oxidation State:
Also known as oxidation number.
Primary Cell:
A cell that cannot be recharged.
Redox Spontaneity Rule:
A spontaneous redox reaction occurs only if the oxidizing agent (OA) is above the reducing agent (RA) in a table of relative strenthgs of oxidizing and reducing agents.
Redox Table:
A table listing standard reduction potentials of common oxidizing agents and reducing agents in order from strongest to weakest. Also known as a standard potential table.
Reducing Agent:
The reactant that is oxidized (loses or gives up electrons to another substance) during an oxidation-reduction reaction.
Reduction:
The process in which one or more electrons is gained by a chemical entity.
Sacrificial Anode:
A form of cathodic protection in which the oxidation of a more active metal is attached to the steel prevents the iron in the steel from being oxidized.
Salt Bridge:
A tube that contains an electrolyte solution and connects the two half-cells in a galvanic cell.
Secondary Cell:
A cell that can be recharged by being attached to an external source of electrical energy; recharging reverses the chemical reaction that generates the electrical energy.
Single Displacement Reaction:
Also called single-replacement reaction, is a type of oxidation-reduction chemical reaction when an element or ion moves out of one compound and into another. That is, another in a compound replaces one element. This is represented by the general reaction scheme: A + BC → AC + B.
Standard Cell:
A galvanic cell in which all the entities involved in the half-cell reactions are at SATP and the solutions have a concentration of 1.0 mol/L.
Standard Cell Potential (ΔE0r(cell)):
The electric potential difference of a galvanic cell that is operating under standard conditions.
Standard Hydrogen Half-Cell:
The galvanic cell from which all the half-cell potentials are determined; E0r = 0 V (by definition).
Standard Reduction Potential (E0r):
The ability of a half-cell to attract electrons in a cell that is operating under standard conditions.
Volt (V):
The SI unit of a galvanic cell, the SI unit for electric potential. Its unit symbol is V, where 1 V is equal to Joules per Coulomb, or J/C.
Voltaic Cell:
Also known as a galvanic cell.
Voltmeter:
An instrument for measuring electric potential in volts.
References
- Picture on title retrieved from: http://arizonaroofingguy.com/wp-content/uploads/2010/10/glossaryroofing.png
- Di Guiseppe, M., Haberer, S., Salciccioli, K., Sanader, M, Vavitsas, A. (2012) Chemistry 12. Toronto: Nelson Education Ltd.
- van Kessel, H., Jenkins, F., Davies, L., Plumb, D., Di Guiseppe, M., Lantz, O., Tompkins, D. (2003). Chemistry 12. Toronto: Thomson Canada Limited.
- http://www.wikipedia.org