Question

Calculate the activation energy of the following electrochemical reaction: 2Fe^3+(aq) + 2I^-(aq) → 2Fe^2+(aq) + I2(s) Given that the reaction rate constant at 25°C is 1.0 × 10^-3 s^-1, and the reaction's activation energy follows the Arrhenius equation with a pre-exponential factor of 8.0 × 10^7 s^-1.

Answer 1

To calculate the activation energy  Ea  of the reaction, we will use the Arrhenius equation:k = A * exp -Ea /  R * T  where k is the rate constant, A is the pre-exponential factor, R is the gas constant  8.314 J/molK , and T is the temperature in Kelvin.First, we need to convert the temperature from Celsius to Kelvin:T = 25C + 273.15 = 298.15 KNow, we can rearrange the Arrhenius equation to solve for Ea:Ea = -R * T * ln k / A Plugging in the given values:Ea = -8.314 J/molK * 298.15 K * ln 1.0  10^-3 s^-1 / 8.0  10^7 s^-1 Ea = -8.314 * 298.15 * ln 1.25  10^-11 Ea  193,000 J/molThe activation energy for the electrochemical reaction is approximately 193 kJ/mol.