Chemistry

# Key Terms

ChemistryKey Terms
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) and current is measured in amperes $(1 A=1Cs)(1 A=1Cs)$
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 $(1 V=1JC)(1 V=1JC)$
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
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 produces a balanced overall oxidation-reduction reaction by splitting the reaction into an oxidation “half” and reduction “half,” balancing the two half-reactions, and then combining the oxidation half-reaction and reduction half-reaction in such a way that the number of electrons generated by the oxidation is exactly canceled by the number of electrons required by the reduction
inert electrode
electrode that allows current to flow, but that does not otherwise participate in the oxidation-reduction reaction in an electrochemical cell; the mass of an inert electrode does not change during the oxidation-reduction reaction; inert electrodes are often made of platinum or gold because these metals are chemically unreactive.
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
(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 $(Ecell°)(Ecell°)$
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; can be calculated by subtracting the standard reduction potential for the half-reaction at the anode from the standard reduction potential for the half-reaction occurring at the cathode
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; the reference point for standard reduction potentials
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
Do you know how you learn best?
Kinetic by OpenStax offers access to innovative study tools designed to help you maximize your learning potential.
Order a print copy

As an Amazon Associate we earn from qualifying purchases.