Studied by 10 peopleelectrochemistry
the study of chemical reactions that produce electricity and chemical reactions that take place because electricity is supplied
what are examples of electrochemical processes?
electroplating, electrolysis of water, production of aluminum metal, production and storage of electricity in batteries
what types of reactions are involved in electrochemical reactions?
redox reactions
why is indirect electron transfer needed for a redox reaction to produce energy?
no useful work can be done by the electrons
describe indirect electron transfer
two half reactions are physically separated and connected by the wire; electrons lost in oxidation flow through the wire to the reduction half
electrochemical cells
cells that use indirect electron transfer to produce electricity by a redox reaction, or use electricity to produce a desired redox reaction
galvanic (voltaic) cells
cells that produce electricity using a redox reaction
electrodes
portions of a cell that conduct electrons in the redox reaction
electrode compartments
solutions in which the electrodes are immersed
salt bridge
an inverted U-tube that holds a gel containing a concentrated electrolyte solution
why is a salt bridge needed in a galvanic cell?
to maintain electrical neutrality; otherwise, solutions will build up a postive or negative charge
anode
electrode at which oxidation takes place
anode compartment
electrolyte solution at which oxidation takes place
cathode
electrode at which reduction takes place
cathode department
electrolyte solution at which reduction takes place
in a galvanic cell, what are the signs of the anode and the cathode?
anodes are negative, cathodes are positive
inert (inactive) electrode
a solid conducting electrode that does not take part in the redox reaction
what are common inert electrodes?
graphite and platinum
cell notation
shorthand notation representing a galvanic cell
standard reduction potentials
the potential of a half-cell at 298 K with all components in their standard states and gases at 1 atm
standard cell potential
the potential (voltage) associated with a cell at standard conditions
the value of a standard cell potential for a galvanic cell must be
positive
the standard cell potential can be calculated by
substracting the standard cell potential of the cathode from the anode
electrolytic cells
cells using electricity from an external source to produce a desired redox reaction
what are some electrolytic cells?
electroplating and reacharging an automobile battery
electrolysis
decomposition of a compound with electricity
in an electrolytic cell, what are the signs of the anode and the cathode?
the anode is postiive and the cathode is negative
Faraday’s constant
96485 J/V mol
equation for Gibbs free energy of a reaction
delta G°=inFE°cell
equation for the equilibrium constant of a redox reaction
E=0.0592 V/n log K
Nernst equation
Ecell=Ecell°- RT/nF lnQ
what is the most common nonstandard condition?
the molarity is no longer 1 M
concentration cell
an electrochemical cell in which the same chemical species is used in both cell compartments
what instrument is used to measure cell potential?
voltmeter (potentiometer)
Note
Flashcard