Electrochemistry Flashcards
Redox reaction
transfer of electrons from one molecule to another
what do we mean by electric current
moving charged particles
what can electron transfer do..
measure voltage and current
sodium half reaction to form a positive ion
Na -> Na^+ + e^-
oxidation
loss of electrons
reduction
gain of electrons
half reactions have an electrode potential…
it’s a voltage we can measure
which electrode does reaction occur?
positive electrode (cathode)
which electrode does oxidation occur?
negative electrode (anode)
what reference point in electrochemistry?
standard hydrogen electrode
reference electrode
silver and silver chloride (Ag/AgCl)
Potentiometry
measuring voltage
what do electrode potentials depend on?
the nature of its half reaction.
the concentrations of the molecules in the half reactions.
Electrode potential is proportional to…
the natural log of the concentration
electrochemsitry calibration graph
potential (on y-axis) and ln (ion conc) (on x-axis) forms a straight line going downwards
how are we going to use potentiometry?
measure voltages using ion selective electrodes to determine concentrations
most common ion selective electode
pH meter
electrode on right is…
reference electrode
electrode on left…
ion selective electrode
inside the electrode there is…
an internal electrolyte (solution)
Amperometry
the measure of electric current that flows when a constant external voltage is applied
what gives us an electric current?
when electrons move from electron donor to electron receiver
Polarography
measuring how the current flow varies as we change the voltage
