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Standard cell potential (Ecell°) is the cell potential measured when all species are in their ______ states. In practice, this condition means that all gases are at ___, all solutes are at ___ mol*L-1, and all liquids and solids are ____.
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3 steps on writing a cell reaction corresponding to a cell diagram
- write the equation for the electrode on the right of the cell diagram as a reduction half-reaction (rmbr: right for reduction)
- write the equation for the electrode on the left of the cell diagram as an oxidation half-reaction
- multiply one or both equations by a factor if necessary to equalize the number of electrons, and then add the two equations.
- If the cell potential is positive, then the reaction is spontaneous as written, if it negative, then the reverse reaction is spontaneous
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Which is the cathode under standard conditions and why? What is the overall standard potential?
MnO4- + 8H+ + 5e- → Mn2+ + 4H2O E=+1.51 V
Cr2O72- + 14H+ + 6e- → 2Cr3+ + 7H2O E=+1.33V
- The 1st one is, because the half reaction with higher standard potential is the cathode in a cell reaction with a positive potential
- E = E(reduction) - E(oxidation) = 1.51V - 1.33V = +0.18V
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If solving for reaction gibbs free energy for Cu & Zinc ions, and your potential difference is +1.04V, which equation is used? What is the value of n?
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