Which of the following reactions is an oxidation carried out by A. ferrooxidans?
a. Fe²⁺ → Fe³⁺
b. Fe³⁺ → Fe²⁺
c. CuS→ CuSO₄
d. Fe⁰ → Cu⁰
e. none of the above

Verified step by step guidance

1. Identify the role of A. ferrooxidans: It is a chemolithoautotrophic bacterium known for oxidizing iron and sulfur compounds.
2. Understand oxidation: Oxidation involves the loss of electrons, resulting in an increase in oxidation state.
3. Analyze option a: Fe²⁺ → Fe³⁺. This involves the loss of an electron, indicating oxidation.
4. Analyze option b: Fe³⁺ → Fe²⁺. This involves the gain of an electron, indicating reduction, not oxidation.
5. Analyze option c: CuS → CuSO₄. This involves the oxidation of sulfur, which is a known reaction for A. ferrooxidans.

Key Concepts

Oxidation-Reduction Reactions

Oxidation-reduction (redox) reactions involve the transfer of electrons between substances. In oxidation, a substance loses electrons, resulting in an increase in its oxidation state, while reduction involves gaining electrons and a decrease in oxidation state. Understanding these processes is crucial for identifying which reactions involve oxidation.

A. ferrooxidans

Acidithiobacillus ferrooxidans is a chemolithotrophic bacterium known for its role in the bioleaching of metals and the oxidation of iron and sulfur compounds. It oxidizes ferrous iron (Fe²⁺) to ferric iron (Fe³⁺), which is a key reaction in its metabolic processes. Recognizing the metabolic capabilities of A. ferrooxidans helps in determining which reactions it can catalyze.

Oxidation States of Iron

Iron can exist in multiple oxidation states, primarily +2 (ferrous, Fe²⁺) and +3 (ferric, Fe³⁺). The conversion of Fe²⁺ to Fe³⁺ represents an oxidation reaction, as it involves the loss of an electron. Understanding these oxidation states is essential for analyzing the reactions presented in the question.