Electrochemistry (5/16) Flashcards
Standard reduction potential
E0
measured in volts
used to refer to any reduction half-reaction
More positive reduction potential
likes to be reduced, more spontaneous
Electrochemical cell
uses electric energy to make a reduction reaction happen
Anode
site of oxidation
Catode
site of reduction
Galvanic cells
A spontaneous reaction is used to generate a positive potential difference that drives a current
E0 must always be positive
Finding reaction direction in a galvanic cell 1
1: identify which reaction happens at the cathode and which happens at the anode, reverse the half reaction at the anode and flip its sign and add potentials
Finding reaction direction in a galvanic cell 2
2: identify which reaction happens at the cathode and which happens at the anode, Ecell= Ecathode- Eanode to find the different in reduction potential
Daniell cell
two half cells connected by a wire and a salt bridge
ions can travel back and fourth
Concentration cell
electrodes must be the same material
two regions must have concentration difference
anode to cathode
Electrolytic cells
electrical energy is used to drive a non-spontaneous redox reaction
negative E0
Electroplating
non-spontaneous reduction of metal ion in solution
results in a deposition of solid metal onto cathode
mol=IT/nF
current*time/ mole e- * Faraday’s constant
Rechargeable batteries
Can either discharge (galvanic)spontaneously or recharge (electrolytic), allowing multiple uses
Lead acid battery
has a relatively low energy density or low energy to mass ratio
used in some applications today
Nickle cadium
cathode and anode
