Final answer:
In a redox reaction involving HNO3 as an oxidant, 4 moles of electrons are transferred to 1 mole of HNO3, resulting in the reduction of nitrate to nitric oxide. The redox potential helps explain the ease with which this electron transfer occurs, and examining half-reactions gives insight into the individual oxidation and reduction processes that occur.
Step-by-step explanation:
When HNO3 acts as an oxidizing agent and gets reduced, 4 moles of electrons are transferred to 1 mole of nitric acid. Reduction, in this case, refers to the gain of electrons. In an electrochemical or redox reaction, the substance gaining electrons is being reduced and is called the oxidizing agent or oxidant. Nitrate (NO3-) ions in HNO3 gain electrons to form nitric oxide (NO) as part of the reduction process. The overall reaction where nitrate is reduced typically involves the intermediate formation of nitric oxide, which can further react with oxygen in the air to form nitrogen dioxide (NO2), known for its characteristic brown color.
Understanding the redox potential is also crucial in these reactions as it measures the tendency of a substance to gain electrons. The half-reactions involved in the process show the individual steps of oxidation and reduction. Combining these half-reactions gives the overall balanced chemical equation.