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Using NERST Eqn. Impact of NON-Standard Conditions on Voltaic Cells. Help ! Help! My battery is dead!. As redox rxn progresses, concentrations of ions in anode + cathode cell changes. Eventually, flow of e- stops, E = 0 and … cell is dead.
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Using NERST Eqn Impact of NON-Standard Conditions on Voltaic Cells
Help ! Help! My battery is dead! • As redox rxn progresses, concentrations of ions in anode + cathode cell changes. • Eventually, flow of e- stops, E = 0 and … cell is dead. • Cell will discharge e- until it reaches equilibrium, termed the dead cell, Q = K and E = 0. • At equilibrium, G= 0.
Effect of [Concentration] on Ecell • NERST Eqn takes into account solns NOT at 1M: Gibbs Free Energy G Gas Constant R (8.31 J/mol-K) Temperature in (K)elvin Moln Faraday’s ConstantF Cell PotentialEcell Reaction Quotient Q [Products]/[Reactants]
The NERST Equation • Use NERST to explore ion concentration changes during redox reactions. @ 25 °C
Sample Exercise 20.11 p. 850 • Sample Exercise 20.12 p. 850
TAKE HOME MESSAGE p. 850 • Increasing [reactants] or decreasing [products] results in HIGH E! • Decreasing [reactants] or increasing [products] results in LOW E! • In comparison with Eat Standard Conditions.