Electrochemistry Flashcards
what does potentiometry study
voltage versus concentration
thermodynamics
what does coulometry study
charge vs concentration
stoichiometry
what does amperometry study
concentration vs kinetics
what does electrochemical impedance study
impendance vs concentration
mechanism
what equation for potentiometry
nersnt equation
in potentiometry, the redox reaction is what (3 things)
reversible/equilibrium, stable in potential, stable with time
what equation for coulombetry
farady equation
in coulombetry, where does the current come from
electron transfer reactions
what occurs at the anode
oxidation
what occurs at the cathode
reduction
what is the electrolyte
solution capable of conducting current
what is a galvanic cell
cell develops spontaneous potential difference
in a galvanic cell, what happens at the external wire, and the ion solution
electrons carry current, ion carry current
what is the working (indicator) electrode
surface at which the reaction takes place
what is the reference electrode
maintains a constant potential is that is independent of current flow
what is the counter electrode
current supporting electrode, does not influence reaction or potential of interest
in a three electrode electrochemical cell, what measures the current, potential, reactions
working electrode/counter electrode
working electrode/reference electrode
working and counter electrodes
is the galvanic cell a two or three electrode system
two
in a two electrode system, I cannot equal
0
in a three electrode system, I =
0
why is the current between WE and RE in a three electrode system almost zero
bc potential is controlled
WE are usually what
inert metals and graphite
counter electrodes are what
inert metals and graphie with a large surface area
reference electrodes are what
S.H.E or Ag/AgCl
a two compartment cell is a
h cell
a three compartment cell is a
e cell
how is a h cell set up
WE in one side, CE in the other
how is a t cell set up
CE in left, WE in middle, RE in right
what are the two functions of a potentiostat
- measure and control voltage difference between WE and RE
2. Measures current flow between WE and CE
three components of a potentiostate
control amplifier, electrometer, current-to-voltage converter
what does the control amplifier do
supplies power to maintain the controlled potential between WE and RE.
what does the electrometer do
measures the potential difference between the RE and WE
what does the current-to-voltage converter do
measures current between WE and CE
three types of noise
intrinsic, external pick up, and internal noise
electrochemical cell; electrolyte solutions are what type of noise
intrinsic
nearby RF; other instrumentation are what type of noise
external pick up
generated within the potentiostat is what type of noise
internal
what is the solution to intrinsic noise
purify the system
solution to external pick up
shielding with a faraday cage
solution to internal noise
filter
two types of electrode processes
fradaic and non faradaic
what is a faradaic process
oxidation or reduction governed by faraday’s law
what is a non faradaic process
charging of a double later not due to redox reactions
charge (electrons) flow from what to what when current is present
negative electrode to positive electrode
