Question
Sat December 22, 2012 By: Shashank Mishra
 

how to caaculate n in nerst equation

Expert Reply
Sun December 23, 2012
The Nernst Equation allows us to calculate the voltage produced by any electrochemical cell given Eo values for its electrodes and the concentrations of reactants and products.
The general Nernst Equation: E = Eo -(RT/nF)lnQ 
      Eo = standard electrochemical cell potential (voltage) 
      R = ideal gas constant 
      T = temperature 
      n = moles of electrons 
      F = Faraday constant = 96,485 C mol-1 
      Q = mass-action expression (approximated by the equilibrium expression)
 
At 25oC the Nernst Equation is simplified to: E = Eo -(0.0592/n)logQ 
      Eo = standard electrochemical cell potential (voltage) 
      n = moles of electrons 
      Q = mass-action expression (approximated by the equilibrium expression)
 
For a system at equilibrium at 25oC, E = 0 and the Nernst Equation is simplified to:
      Eo = (0.0592/n)logK 
      Eo = standard electrochemical cell potential (voltage) 
      n = moles of electrons 
      K = equilibrium expression
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