G Chem Electrochemistry Flashcards
The more positive E(naught) value, the more likely the reaction will occur…?
Spontaneously
Strongest reducing agents have large ____ E(naught) values
Large negative
Strongest oxidizing agents have large _____ E(naught) values
Large positive
Galvanic cells mneumonic
LEO is a GERC
Lose electrons oxidation is anode
Gain electrons reduction is cathode
Nernst equation
Ecell = E(naught)cell - (RT/nF)(lnQ)
Ecell is cell potential
E(naught)cell is cell potential under std-state conditions
R = 8.314 J/mol*K
n = # moles e- transferred in balanced equation
F = Faraday’s constant 95,484.56 C/mol
Q = reaction quotient at specific moment in time
Plank’s constant
6.626 x 10^-34 J*s
Galvanic cells are also referred to…?
Voltaic cells
Define a salt bridge
Used in galvanic cells, contains an inert electrolyte whose ions will diffuse into the separate half-cells to balance the building charges at the electrodes
Which reaction (cathode or anode) serves as the source of e- in galvanic cells?
Anode
The anode is the (+/-) terminal in galvanic cells?
Negative
Galvanic cells have a (+/-) EMF?
+
How do you find the overall EMF for galvanic cells?
- Typically given 2 REDUCTION potentials
- Need to flip one for the oxidation potential
- Decide which one to flip so that when added to the other EMF, you will get an overall + value
Calculating Gibbs Free Energy from EMF (equation)
ΔG(naught) = -nFE
n = moles of e- transferred E(naught) = std state EMF F = faraday’s constant 96,485 C/mol e-
Electric potential energy (equation)
U = qV q= charge V = volts
Define: concentration cell
Specific form of galvanic cell with two equivalent half-cells of the same material differing only in concentrations, producing a small voltage as it attempts to reach equilibrium
What happens when Q = 1 for galvanic cells (Q is the reaction quotient)
The cell reaches equilibrium, and is considered “dead” since the two concentrations are equal (E is also = 0)
Define: electrolytic cell
An electrochemical cell in which the energy from an external power source is used to drive a normally non-spontaneous reaction
The anode is the site of _____ in an electrolytic cell
Oxidation
The anode is the (+/-) terminal of an electrolytic cell
+
For an electrolytic cell, the overall EMF value will be (+/-)?
Negative (indicates the amount of energy required to drive the reaction)
Increasing reduction potentials (more positive) indicate increasing strength of _____?
Oxidizing agent (more likely to be reduced)
More negative reduction potentials indicate increasing strength of _____?
Reducing agents
An OA can oxidize any RA that lies (above/below) it on our std reduction potential table
Below (more negative)
