Equilibrium cells Thermodynamic measurements and potentiometric sensors

1 Equilibrium cells Thermodynamic measurements and potentiometric sensors 

Absolutely symmetrical cells naturally exhibit a zero voltage in the currentless state at electrochemical equilibrium. Let us consider a simple asymmetrical cell, namely an oxygen concentration cell with the oxygen ion conductor made from Y203-doped Zr02 

The incorporation equilibrium applies at each phase boundary  

Calculating the difference at the two phase boundaries yields EF = — AolMs- = — 2 oL/t o2- + 

When formally constructing the overall cell reaction from the difference of the two electrode reactions, it should be noted that in contrast to purely chemical reactions, the spatial separation of the reactants by an electrolyte is crucial the different electrical potentials correspond to sites 0 and L 0 truly cancels in the balance since Jlo - is constant, while the difference between the electron terms leads to the voltage, so that the affinity of the overall (chemical) reaction 

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