how to caaculate n in nerst equation

Asked by shashank mishra | 22nd Dec, 2012, 10:43: PM

Expert Answer:

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

Answered by  | 23rd Dec, 2012, 08:21: AM

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