Ch. 12: Electrochemistry Flashcards
what reactions occur in electrochemical cells
oxidation-reduction rxns
contained systems
what occurs at electrodes
oxidation-reduction rxns within electrochemical cells
what electrodes do oxidation and reduction occur at, specifically
AN OX // RED CAT
oxidation at anode, reduction at cathode
what is the electromotive force in regards to the electrochemical cells
voltage or electric potential difference within the cell
positive: cell can release energy, deltaG<0, spontaneous
negative: cell absorbs energy, deltaG>0, nonspontaneous
what is the direction of flow of electrons in an electrochemical cell
from anode to cathode
wha is the direction of flow of current in an electrochemical cell
from cathode to anode
galvanic cells
- spontaneous –> free energy negative, EMF is positive
- non rechargeable
- contains two distinct electrodes surround by electrolyte solution in two half cells connected by conductive wire and salt bridge
what is the purpose of a salt bridge
permits the exchange of cations and anions by dissipating the charge gradient
electrolytic cells
- non spontaneous –> free energy positive, EMF negative
- driven by an external voltage source
what is electrolysis
external voltage source that drives electrolytic cell reactions
what is the electrodeposition equation
mol M = It/nF
I = current, t = time, n = electron equivalents, F = faraday constant
concentration cell
- galvanic cell*
- electrodes are chemically identical
what type of cells are rechargeable cells
rechargeable cells can function as both a galvanic and electrolytic cell
–> lead-acid, nickel-cadminum, nickel-metal hydride
what are surge currents
periods of large current early in the discharge cycle
what are the positive and negative electrodes of galvanic cells
anode = negative, cathode = positive
