Dynamics of anodic process of gold electrode in thiourea solution in the presence of sulfur dioxide

The electrochemical kinetics equation of the oxidation of gold in thiourea solution in the presence of sulfur dioxide was given out. The kinetic parameters are determined as: the transmission coefficient β=0.477; when the reaction time is zero, the initial over potential of the oxidation of gold in acid thiourea solution is 0.267 V. The dynamics of anodic process of gold electrode was studied by using Tafel plots. In the solution containing 5×10-6 mol/L sulfur dioxide the activated energy is 46.11 kJ/mol. When the electrode potential is higher than 270 mV, the gold is oxidized by thiourea. The addition of H2SO3 can obviously improve the corrosion speed of gold.