One of the first developments of extractive metallurgy was the leaching of gold. The cyanidation of gold is an electrochemical process, comprising the oxidation of gold by oxygen and reduction of oxygen to hydroxide in the presence of excess cyanide, resulting in the famous Elsner's equation for gold extraction: 4Au+8CN+O2+H2O4Au(CN)2+4OH Calculate the mass-transfer coefficient (m/s) for a gold particle with a diameter of 70m and a density of 19.3g/cm3, to completely dissolve after 100 hours, by assuming that the extraction rate is controlled by the dissolution of oxygen with a solubility of 2.5104mol/L