ANACHEM 11 12 Flashcards
relationship between chemical reaction
and electricity (movement of electrons
ELECTROCHEMISTRY
it is the measurement of current/voltage
generated by the activity of an ion
ELECTROCHEMISTRY
Electrochemistry Analysis
- redox titration
- potentiometry - widely used
- amperometry
- polarography
- electrogravimetry
- voltammetry
- A pair of
electrodes in contact with an electrolyte
solution
Electrochemical Cell
An
electrochemical cell which
spontaneously produces current (or
energy) when the electrodes are
connected externally by a
conducting wire.
. Galvanic or Voltaic Cell -
An electrochemical cell through
which current is forced by a battery
or some other external source of
energy. (such as battery, DC,
alternate current)
Electrolysis or Electrolytic Cell
The
algebraic sum of the individual electrode
potentials of an electrochemical cell at
zero current
Theoretical Cell Potential -
- the amount of
potential that is lost on the way from the
reference electrode to the working
electrodes.
Ohmic Drop, IR
A potential
developed across a boundary between
electrolytes differing in concentration or
chemical composition
Liquid-junction Potential
one way of measuring how
easily the substance loses on
electron.
Standard Electrode Potential
Electrode potential
measured in solutions where all
reactants and products are at
unit activity.
Standard Electrode Potential
The potential
of an electrode measured relative to a
standard, usually the SHE. It is a
measure of the driving force of the
electrode reaction and is temperature
and activity dependent
Electrode Potential E
This consists of a platinum electrode
coated with platinum black to catalyze
the electrode reaction and over the
surface of which hydrogen at 760 mm of
mercury is passed.
Standard Hydrogen Electrode
One in which the halfcell reactions are reversed by reversing
the current flow; such a cell is said to be
in thermodynamic equilibrium
REVERSIBLE CELL
The electrode at which
reduction occurs
CATHODE
The electrode at which
oxidation occurs.
ANODE
occur together but opposite
direction.
Half-cell Reactions
The additional
potential required to cause some
electrode reactions to proceed at an
appreciable rate
Activation Overpotential
Oxidation or reduction reaction
occurring at an electrode
Half-cell Reactions
In an oxidation/reduction reaction
electrons are transferred from one
reactant to another. (occurs together)
REDOX REACTIONS
consists of two conductors called
electrodes, each of which is
immersed in an electrolyte solution.
Electrochemical Cells
- the
additional voltage that is needed to carry
out electrolysis in addition to the
standard cell potential.
Concentration Overpotential
In most of the cells that will be of
interest to us, the solutions
surrounding the two electrodes are
different and must be separated to
avoid direct reaction between the
reactants
Electrochemical Cells
consume
electricity. In contrast to a voltaic cell,
requires an external source of
electrical energy for operation.
electrolytic cells
store electrical
energy.
Galvanic cells
: In redox
methods an indicator electrode is used
to sense the presence or change in
concentration of the oxidized and
reduced forms of a redox couple.
INDICATOR ELECTRODE