ABSTRACT
Electrolysis can be used for the extraction (electrowinning) of metals from either aqueous solutions or molten salts and for the purification (electrorefining) of crude metal obtained by other extraction routes. The principles involved are readily appreciated from consideration of a galvanic cell, which consists of two plates or rods of dissimilar metals partially immersed in an electrolyte and connected by an external circuit. When Cu and Zn are selected for the electrodes, both metals are soluble in a sulfuric acid electrolyte. The half-cell reactions are: () Cu 2 + 2 e − = Cu, E o = + 0.34 V https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203736722/bc1139bf-b5ce-4f71-b06f-b224495a2dc9/content/eq486.tif"/> () Zn 2 + 2 e − = Zn, E o = − 0.76 V https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203736722/bc1139bf-b5ce-4f71-b06f-b224495a2dc9/content/eq487.tif"/>
