Final answer:
To balance redox reactions in acidic solutions, use H₂O(l) to balance oxygen and H⁺ (aq) to balance hydrogen. The Half-Reaction Method provides a systematic way of balancing the reaction by adding appropriate species to balance elements and charge. So the correct answer is A and B.
Step-by-step explanation:
When preparing to balance complicated oxidation-reduction reactions that occur in acidic solutions, you can use H₂O (l) to balance oxygen atoms and H⁺ (aq) to balance hydrogen atoms. Hydroxide ions (OH⁻ (aq)) are also at times used, but typically in the context of balancing reactions in basic solutions.
Therefore, options (a) H₂O(l) and (b) H⁺ (aq) can be used in acidic solutions. The process can be efficiently carried out using the Half-Reaction Method, also known as the ion-electron method, which systematically balances the redox reaction in a step-by-step approach.
In an acidic medium, after initially writing down the half-reactions, you proceed by balancing all elements except for hydrogen and oxygen, using water molecules to balance oxygen, and then adding hydronium ions to equalize the hydrogen atoms. A charge is balanced by adding electrons, and if the reaction occurs in a basic solution, hydroxide ions are used to neutralize the excess hydrogen ions.