Question

Calculate the polarization that occurs in an electrochemical cell when a current of 2 A flows through it for 10 minutes. The electrode area is 25 cm², and the current efficiency is 95%. The activation energy is 80 kJ/mol, and the reaction quotient is 2.5 x 10⁻⁵. The temperature of the cell is 25°C. Find the polarization resistance and the total polarization of the cell.

Answer 1

To calculate the polarization resistance and the total polarization of the electrochemical cell, we need to consider the Butler-Volmer equation, which relates the current density  j  to the overpotential    in an electrochemical cell:j = j  exp a * F *  / RT  - exp -c * F *  / RT  where:j = exchange current densitya = anodic transfer coefficientc = cathodic transfer coefficientF = Faraday's constant  96485 C/mol R = gas constant  8.314 J/molK T = temperature in Kelvin  25C = 298.15 K  = overpotentialFirst, we need to find the current density  j  by dividing the current  I  by the electrode area  A :j = I / A = 2 A /  25 cm *  1 m / 10000 cm   = 2 A / 0.0025 m = 800 A/mNext, we need to find the exchange current density  j . We can use the Tafel equation to relate the exchange current density to the activation energy  Ea  and the reaction quotient  Q :j = A * exp -Ea /  RT  * ln Q  where A is the pre-exponential factor. Unfortunately, we don't have enough information to calculate j, as we don't know the values of A, a, and c. Therefore, we cannot calculate the polarization resistance and the total polarization of the cell using the given information.However, if you provide the missing parameters, we can continue with the calculations.