Question

Derive the Nernst Equation for a specific electrochemical cell and calculate its EMF.

Hint:

At 25°C, always use \(0.0591/n\) for आसान calculation.

Answer 1

Concept: The Nernst Equation relates the electrode potential of a cell to the standard electrode potential, temperature, and concentrations of reactants and products.
Answer:
For a general electrochemical reaction: \[ aA + bB \rightarrow cC + dD \] The Nernst Equation is: \[ E = E^\circ - \frac{RT}{nF} \ln Q \] where:

• \(E\) = EMF of the cell
• \(E^\circ\) = Standard EMF
• \(R\) = Gas constant
• \(T\) = Temperature in Kelvin
• \(n\) = Number of electrons transferred
• \(F\) = Faraday constant
• \(Q\) = Reaction quotient

At \(25^\circ C\) (298 K), the equation becomes: \[ E = E^\circ - \frac{0.0591}{n} \log Q \] Example:
For a Daniell cell: \[ Zn + Cu^{2+} \rightarrow Zn^{2+} + Cu \] \[ E = E^\circ - \frac{0.0591}{2} \log \frac{[Zn^{2+}]}{[Cu^{2+}]} \] By substituting concentration values, EMF can be calculated.