Consider an electrochemical cell with a copper metal electrode immersed in a solution of copper sulfate, and a platinum electrode in a solution of hydrogen sulfate. The current is measured at 25°C while the cell potential is varied. The following data is obtained for the anodic and cathodic currents:Anodic current:Cell potential (V): 0.20 0.30 0.40 0.50 0.60Current (mA): 1.01 1.80 3.04 4.58 6.25Cathodic current:Cell potential (V): -0.20 -0.30 -0.40 -0.50 -0.60Current (mA): -1.00 -1.79 -3.02 -4.54 -6.19Calculate the anodic and cathodic Tafel slopes for this electrochemical cell.

Question

Consider an electrochemical cell with a copper metal electrode immersed in a solution of copper sulfate, and a platinum electrode in a solution of hydrogen sulfate. The current is measured at 25°C while the cell potential is varied. The following data is obtained for the anodic and cathodic currents:Anodic current:Cell potential (V): 0.20  0.30  0.40  0.50  0.60Current

Answer 1

To calculate the anodic and cathodic Tafel slopes, we first need to understand the Tafel equation, which is given by: = b * log10 i / i0 where  is the overpotential  V , b is the Tafel slope  V/decade , i is the current density  mA/cm , and i0 is the exchange current density  mA/cm .We can rearrange the equation to solve for the Tafel slope  b :b =  / log10 i / i0 Since we don't have the values for i0, we can use the difference between two data points to calculate the Tafel slope: = b * log10 i2 / i1 b =  / log10 i2 / i1 Now, let's calculate the anodic and cathodic Tafel slopes using the given data.Anodic Tafel slope:Choose two data points, for example,  0.20 V, 1.01 mA  and  0.30 V, 1.80 mA . = 0.30 V - 0.20 V = 0.10 Vi2 = 1.80 mAi1 = 1.01 mAb_anodic = 0.10 V / log10 1.80 mA / 1.01 mA   0.121 V/decadeCathodic Tafel slope:Choose two data points, for example,  -0.20 V, -1.00 mA  and  -0.30 V, -1.79 mA . = -0.20 V -  -0.30 V  = 0.10 Vi2 = -1.00 mAi1 = -1.79 mAb_cathodic = 0.10 V / log10 -1.00 mA / -1.79 mA   0.120 V/decadeSo, the anodic Tafel slope is approximately 0.121 V/decade, and the cathodic Tafel slope is approximately 0.120 V/decade.