Complete the exercises below. Write complete balanced half-reactions for: a. reduction of nitrate ion to NO in acidic solution, b. oxidation of HNO₂ to NO₂ in acidic solution.

Half-reactions are equations that show either the reduction or oxidation process occurring in a redox reaction. They are essential for balancing redox reactions, as they separate the two processes, allowing for a clearer understanding of electron transfer. Each half-reaction includes the species being oxidized or reduced, along with electrons, protons, and any other necessary ions to balance the charge and mass.

An acidic solution is one where the concentration of hydrogen ions (H⁺) is higher than that of hydroxide ions (OH⁻). In redox reactions occurring in acidic conditions, protons are often added to balance the charge in half-reactions. Understanding the role of H⁺ ions is crucial for accurately writing balanced half-reactions, especially when dealing with species that change oxidation states.

Oxidation states (or oxidation numbers) indicate the degree of oxidation of an atom in a compound. They help in identifying which species is oxidized and which is reduced in a redox reaction. By determining the oxidation states of the reactants and products, one can write balanced half-reactions that reflect the transfer of electrons, ensuring that the overall charge and mass are conserved.