Individuals living near copper mines sometimes earn extra money by suspending iron objects in the mine wastewater. Based on your experimentation, explain why the iron objects would be suspended in the wastewater.
To understand why iron objects are suspended in copper mine wastewater, we need to explore a phenomenon known as galvanic corrosion, specifically in the context of copper and iron.
1. Galvanic Corrosion: Galvanic corrosion occurs when two dissimilar metals are in contact in the presence of an electrolyte (such as water or wastewater). In this case, copper (from the copper mine wastewater) and iron (from the iron objects) are the dissimilar metals.
2. Electrochemical Reaction: When copper and iron come into contact, an electrochemical reaction takes place due to their different electrochemical potentials. The copper acts as the anode (positive electrode), and the iron acts as the cathode (negative electrode). This electrochemical reaction is what leads to the suspension of iron objects.
3. Formation of a Galvanic Couple: The electrochemical reaction establishes a galvanic couple where the copper acts as the sacrificial metal (anode) and the iron as the protected metal (cathode). The copper undergoes oxidation, releasing copper ions into the wastewater, while the iron remains relatively unaffected.
4. Cathodic Protection: As copper ions are released into the wastewater, they create a more positive environment around the iron objects. This positive environment enhances the cathodic protection of the iron objects, preventing or minimizing their corrosion.
5. Suspension Effect: Due to the electrochemical reaction and the protective nature of the copper ions, the iron objects in copper mine wastewater become suspended. The electrical charge difference between the anode (copper) and cathode (iron) causes the iron objects to repel each other, preventing them from sinking or settling.
Therefore, suspending iron objects in copper mine wastewater harnesses the phenomenon of galvanic corrosion, which results in the protection of the iron objects from corrosion and their suspension in the wastewater.