Final answer:
The key reaction catalyzed by Acidithiobacillus ferrooxidans in copper leaching is the oxidation of iron from Fe²⁺ to Fe³⁺, which plays a crucial role in mining processes to extract copper from sulfide minerals.
Step-by-step explanation:
The key reaction that Acidithiobacillus ferrooxidans catalyzes in the copper leaching process is the oxidation of reduced iron (Fe²⁺) to oxidized iron (Fe³⁺). This bacterium is involved in the bioleaching of copper from sulfide minerals, a process in which it uses iron as part of its metabolism, and in doing so, converts Fe²⁺ to Fe³⁺. The oxidized iron (Fe³⁺) can then react with the copper sulfide ore to transform it into a soluble form, thereby aiding in copper extraction.
Other reactions are possible, such as the reduction of Fe³⁺ to Fe²⁺ and the oxidation or reduction of sulfur compounds. However, the oxidation of Fe²⁺ to Fe³⁺ is critical in the context of bacterial leaching because the oxidized iron can further react with the copper ore to mobilize the copper for extraction.
This is in contrast with many other bioleaching organisms that may focus on the direct oxidation of metal sulfides. Acidithiobacillus ferrooxidans is especially valuable in the leaching process due to this ability to oxidize iron, providing an efficient mechanism for the recovery of copper from its ores.