Chapter 16: Introduction to Electrochemistry Flashcards
sometimes called redox reactions
oxidation/ reduction reactions
is an electron donor
reducing agent
is an electron acceptor
oxidizing agents
A substance that has a strong affinity for electrons
oxidizing agent
donates electrons to another species
reducing agent
Oxidation/reduction reactions can be viewed in a way that is analogous to the
Bronsted Lowry concept
TRUE or FALSE
When an acid donates a proton, it becomes a conjugate base that is capable of accepting a proton
TRUE
TRUE or FALSE
when a reducing agent donates an electron, it becomes an oxidizing agent
that can then accept an electron.
TRUE
unique aspect of oxidation/reduction reactions is that the transfer of electrons— and thus an identical net reaction—can often be brought about in an ______ in which the oxidizing agent and the reducing agent are physically separated from one another
electrochemical cell
isolates the reactants but maintains electrical contact between the two halves of the cell.
salt bridge
When a voltmeter of high internal resistance is connected as shown or the electrodes
are not connected externally, the cell is said to be at _______ and delivers the full cell potential
open circuit
When the circuit is open, no net reaction occurs in the cell, although we shall show that the cell has the ________ for doing work
potential
voltmeter measures what
potential difference or voltage, between two electrodes ar any instant
is a measure of the tendency of the cell reaction to proceed toward equilibrium.
voltage
TRUE or FALSE
A cell with zero voltage does not
perform work, as anyone who has found a “dead” battery in a flashlight or in a laptop
computer can attest.
TRUE
The electrodes in some cells share a
common electrolyte; these are known
as
cells without liquid junction
is an electrode where
reduction occurs
cathode
electrode where oxidation occurs
anode
An electrochemical cell consists of two conductors called
electrodes
TRUE or FALSE
The most common way of avoiding mixing is to insert a salt bridge, between solutions
TRUE
stores electrical energy or also known as voltaic cells
galvanic cells
consume electricity
electrolytic cells
are usually made from several such cells connected in series to produce higher voltages than a single cell can produce.
batteries
TRUE or FALSE
There is a liquid junction potential at each interface of cell notation
TRUE
Galvanic cells operate spontaneously, and the net reaction during discharge is called the
spontaneous cell reaction
In this cell, reversing the current reverses the cell
reaction when the direction of flo is changed
reversible cell
In this cell, reversing the current causes a
different half-reaction to occur at one or both of the electrodes.
irreversible cell
was one of the earliest galvanic cells to find widespread practical application
Daneill gravity cell
The phase boundary between an
electrode and its solution is called an
interface
If the reactants and products are in their standard states, the resulting cell potential is called the
standard cell potential
is a reference state that allows
to obtain relative values of such
thermodynamic quantities as free
energy, activity, enthalpy, and
entropy. All substances
standard state
formula of delta G
delta G= -nFEcell =-RTln Keq
requires an external source of electrical energy for operation
electrolytic cell
meets specifications such as an electrode must be easy to construct, reversible, and highly reproducible in its behavior, which has been used throughout the world for many years as a universal reference electrode and is a typical gas electrode
standard hydrogen electrode
The standard hydrogen electrode
is sometimes called the
normal hydrogen electrode
is a layer of finely divided platinum that
is formed on the surface of a smooth platinum electrode by electrolytic deposition of
the metal from a solution of chloroplatinic acid,
platinum black
TRUE or FALSE
By convention, the potential of
the standard hydrogen electrode is assigned a value of 0.000 V at all temperatures
TRUE
is defined as the potential of a cell in which the electrode in question is the right-hand electrode and the standard hydrogen electrode is the left-hand electrode.
electrode potential
is defined as its electrode potential when the activities of the reactants and products are all unity
standard electrode potential
A metal ion/metal half-cell is
sometimes called a
couple
is by
definition a reduction potential
electrode potential
is the
potential for the half-reaction written
in the opposite way. The sign of an
oxidation potential is, therefore,
opposite that for a reduction
potential, but the magnitude is
the same.
oxidation potential
TRUE or FALSE
The standard electrode potential for a half-reaction is temperature dependent
TRUE
The following further complicate application of standard electrode potential data to
many systems of interest in analytical chemistry:
association
dissociation
complex formation
solvolysis equilibria
are empirical potentials that compensate for the types of activity and competing equilibria effects that we have just described.
formal potential
is the electrode
potential when the ratio of analytical
concentrations of reactants and
products of a half-reaction is exactly
1.00 and the molar concentrations
of any other solutes are specified
formal potential
is the potential of the half-cell with respect to the standard hydrogen
electrode measured under conditions such that the ratio of analytical concentrations
of reactants and products as they appear in the Nernst equation is exactly unity and
the concentrations of other species in the system are all carefully specified
formal potential
this rule implies that one should always measure the cell potential by connecting the positive lead of the voltmeter to the right-hand electrode in the schematic or cell drawing and the common, or ground, lead of the voltmeter to the left-hand electrode
plus right rule
potential of hydrogen electrode depends on
temperature
activities of hydrogen ion
molecular hydorgen in the solution
