#4 (Section 20.4) Cell Potentials Electromotive force (emf) is the driving force
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Question
#4 (Section 20.4) Cell Potentials
Electromotive force (emf) is the driving force due to what?
What (not who!) is SHE ?
Look at Fig. 20.11 and describe the spontaneous flow of electrons relative to the reduction potentials:
#5 (Section 20.5) Redox and Free Energy
Consider Faraday’s Equation: DG = - nFE
Under what condition of E is DG negative and spontaneous?
(Recall that in this equation E is define as emf and therefore can yield electrical work.)
#6 (Section 20.6)
Cell potentials under non-standard conditions are observed as a voltaic cell becomes discharged and the concentrations of the reactant and products change (thus, deviate from the standard conc.).
Consider the Nernst Equation: E = Eo - RT/nF ln Q
As the reaction proceeds in a voltaic cell the emf drops and eventually E = 0 (and DG = 0). What is happening to the Q value that causes E and DG values to decrease (ref. page 850, bottom).
Explanation / Answer
potential difference between two half cells is the driving forec.
SHE: standard hydrogen electrode.
If E is positive value then DG also negetive resulting process will be negetive.
once reaction attain equilibrium means potentials become same in both the half cells . Q becomes K.
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