Complete the exercises below. An aqueous solution of SO₂ reduces a. aqueous KMnO₄ to MnSO₄ (aq) b. acidic aqueous K₂Cr₂O₇ to aqueous Cr⁵⁺, c. aqueous Hg₂(NO₃)₂ to mercury metal. Write balanced equations for these reactions.

Redox reactions, or reduction-oxidation reactions, involve the transfer of electrons between species. In these reactions, one substance is oxidized (loses electrons) while another is reduced (gains electrons). Understanding the oxidation states of the elements involved is crucial for identifying which species undergo these changes, as well as for balancing the overall reaction.

Balancing chemical equations is the process of ensuring that the number of atoms for each element is the same on both sides of the equation. This is essential for obeying the law of conservation of mass. Techniques such as the half-reaction method can be particularly useful in redox reactions, where separate oxidation and reduction half-reactions are balanced before combining them into a complete equation.

Acid-base chemistry involves the transfer of protons (H⁺ ions) between reactants. In the context of the given reactions, acidic conditions can influence the oxidation states of certain elements, such as chromium in K₂Cr₂O₇. Recognizing the role of acids and bases in redox reactions is important for predicting the products and balancing the equations correctly.