Question

Consider a reaction where Ag is oxidized to Ag+ ions in a solution containing AgNO3. We set up an electrochemical cell with a Ag/Ag+ electrode as the anode and a platinum electrode as the cathode. The standard electrode potential for the Ag/Ag+ electrode is +0.80 V. What is the overpotential required to achieve a current of 2 A if the applied voltage is 1.00 V?

Answer 1

To calculate the overpotential, we first need to determine the cell potential under the given conditions. The cell potential  E_cell  can be calculated using the Nernst equation:E_cell = E -  RT/nF  * ln Q where E is the standard electrode potential, R is the gas constant  8.314 J/molK , T is the temperature in Kelvin  assuming 298 K, which is approximately 25C , n is the number of electrons transferred in the redox reaction  1 for Ag to Ag+ , F is the Faraday constant  96,485 C/mol , and Q is the reaction quotient.Since we are given the standard electrode potential  E  for the Ag/Ag+ electrode as +0.80 V and the reaction quotient  Q  is not provided, we will assume that the reaction is under standard conditions  Q = 1 . Therefore, the Nernst equation simplifies to:E_cell = EE_cell = +0.80 VNow, we need to calculate the overpotential   . Overpotential is the difference between the applied voltage  E_applied  and the cell potential  E_cell : = E_applied - E_cellGiven the applied voltage  E_applied  is 1.00 V, we can calculate the overpotential: = 1.00 V - 0.80 V = 0.20 VSo, the overpotential required to achieve a current of 2 A with an applied voltage of 1.00 V is 0.20 V.