Term | Definition |
active electrode | electrode that participates in the oxidation-reduction reaction of an electrochemical cell; the mass of an active electrode changes during the oxidation-reduction reaction |
alkaline battery | primary battery that uses an alkaline (often potassium hydroxide) electrolyte; designed to be an exact replacement for the dry cell, but with more energy storage and less electrolyte leakage than typical dry cell |
anode | electrode in an electrochemical cell at which oxidation occurs; information about the anode is recorded on the left side of the salt bridge in cell notation |
battery | galvanic cell or series of cells that produces a current; in theory, any galvanic cell |
cathode | electrode in an electrochemical cell at which reduction occurs; information about the cathode is recorded on the right side of the salt bridge in cell notation |
cathodic protection | method of protecting metal by using a sacrificial anode and effectively making the metal that needs protecting the cathode, thus preventing its oxidation |
cell notation | shorthand way to represent the reactions in an electrochemical cell |
cell potential | difference in electrical potential that arises when dissimilar metals are connected; the driving force for the flow of charge (current) in oxidation-reduction reactions |
circuit | path taken by a current as it flows because of an electrical potential difference |
concentration cell | galvanic cell in which the two half-cells are the same except for the concentration of the solutes; spontaneous when the overall reaction is the dilution of the solute |
corrosion | degradation of metal through an electrochemical process |
current | flow of electrical charge; the SI unit of charge is the coulomb (C), The IS unit of current is the ampere (A). One ampere is the flow of one coulomb in one second. Amperes = Charge (C) divided by time (in seconds) [modified see book] |
dry cell | primary battery, also called a zinc-carbon battery; can be used in any orientation because it uses a paste as the electrolyte; tends to leak electrolyte when stored |
electrical potential | energy per charge; in electrochemical systems, it depends on the way the charges are distributed within the system; the SI unit of electrical potential is the volt (V=J/C) [modified see book] |
electrical work (wele) | negative of total charge times the cell potential; equal to wmax for the system, and so equals the free energy change (ΔG) |
electrolysis | process using electrical energy to cause a nonspontaneous process to occur |
electrolytic cell | electrochemical cell in which electrolysis is used; electrochemical cell with negative cell potentials |
electroplating | depositing a thin layer of one metal on top of a conducting surface |
Faraday’s constant (F) | charge on 1 mol of electrons; F = 96,485 C/mol e− |
fuel cell | devices that produce an electrical current as long as fuel and oxidizer are continuously added; more efficient than internal combustion engines |
galvanic cell | electrochemical cell that involves a spontaneous oxidation-reduction reaction; electrochemical cells with positive cell potentials; also called a voltaic cell |
galvanized iron | method for protecting iron by covering it with zinc, which will oxidize before the iron; zinc-plated iron |
half-reaction method | method that splits oxidation-reduction reactions into their “oxidation half” and “reduction half” to make finding the overall equation easier. [modified, see book page 977, 939] |
inert electrode | electrode that allows current to flow, but that does not otherwise participate in the oxidation- reduction reaction in an electrochemical cell; [truncated, see book page 977] |
lead acid battery | secondary battery that consists of multiple cells; the lead acid battery found in automobiles has six cells and a voltage of 12 V |
lithium ion battery | very popular secondary battery; uses lithium ions to conduct current and is light, rechargeable, and produces a nearly constant potential as it discharges |
Nernst equation | equation that relates the logarithm of the reaction quotient (Q) to nonstandard cell potentials; can be used to relate equilibrium constants to standard cell potentials |
nickel-cadmium battery | (NiCd battery) secondary battery that uses cadmium, which is a toxic heavy metal; heavier than lithium ion batteries, but with similar performance characteristics |
overpotential | difference between the theoretical potential and actual potential in an electrolytic cell; the “extra” voltage required to make some nonspontaneous electrochemical reaction to occur |
oxidation half-reaction | the “half” of an oxidation-reduction reaction involving oxidation; the half-reaction in which electrons appear as products; balanced when each atom type, as well as the charge, is balanced |
primary battery | single-use nonrechargeable battery |
reduction half-reaction | the “half” of an oxidation-reduction reaction involving reduction; the half-reaction in which electrons appear as reactants; balanced when each atom type, as well as the charge, is balanced |
sacrificial anode | more active, inexpensive metal used as the anode in cathodic protection; frequently made from magnesium or zinc |
secondary battery | battery that can be recharged |
standard cell potential (Ecell° ) | the cell potential when all reactants and products are in their standard states (1 bar or 1 atm or gases; 1 M for solutes), usually at 298.15 K; [truncated see book page 978] |
standard hydrogen electrode (SHE) | the electrode consists of hydrogen gas bubbling through hydrochloric acid over an inert platinum electrode whose reduction at standard conditions is assigned a value of 0 V; [truncated see book page 978] |
standard reduction potential (E°) | the value of the reduction under standard conditions (1 bar or 1 atm for gases; 1 M for solutes) usually at 298.15 K; tabulated values used to calculate standard cell potentials |
voltaic cell | another name for a galvanic cell |