Balancing the Ionic Equation: Zn + NO3- → Zn2+ + NH4+

Step 1: Assigning oxidation numbers
- The oxidation number of zinc (Zn) is 0 because it is a pure element.
- The oxidation number of nitrate (NO3-) is -1.
- The oxidation number of zinc (Zn2+) is +2.
- The oxidation number of ammonium (NH4+) is +1.

Step 2: Identifying the oxidized and reduced species
- In this equation, zinc is oxidized from an oxidation number of 0 to +2, so it is the reducing agent.
- Nitrate is reduced from an oxidation number of -1 to 0, so it is the oxidizing agent.

Step 3: Writing the half-reactions
- Half-reaction for oxidation: Zn → Zn2+
- Half-reaction for reduction: NO3- → NH4+

Step 4: Balancing the half-reactions
- Balancing the oxidation half-reaction: Since zinc is being oxidized, we need to add two electrons (e-) to the left side to balance the charge. The balanced half-reaction is: Zn → Zn2+ + 2e-
- Balancing the reduction half-reaction: The nitrogen atom in nitrate (NO3-) has an oxidation number of +5, while the nitrogen atom in ammonium (NH4+) has an oxidation number of -3. To balance the nitrogen atoms, we need to add three electrons (3e-) to the right side. The balanced half-reaction is: NO3- + 3e- → NH4+

Step 5: Balancing the number of electrons transferred
- To equalize the number of electrons in both half-reactions, we need to multiply the oxidation half-reaction by 3 and the reduction half-reaction by 2. This will result in 6 electrons in both half-reactions.
Balanced oxidation half-reaction: 3Zn → 3Zn2+ + 6e-
Balanced reduction half-reaction: 2NO3- + 6e- → 2NH4+

Step 6: Combining the balanced half-reactions
- Now that the number of electrons is balanced, we can combine the two half-reactions into the overall balanced ionic equation:
3Zn + 2NO3- → 3Zn2+ + 2NH4+

Step 7: Final check
- Verify that the equation is balanced in terms of atoms and charge. In this case, there are three zinc atoms, two nitrogen atoms, ten hydrogen atoms, and twelve oxygen atoms on both sides of the equation. The charges are also balanced, with a total charge of -6 on both sides.

Explanation:
The oxidation number method is used to balance ionic equations by assigning oxidation numbers to each element involved. The oxidation half-reaction represents the species losing electrons (oxidation) and the reduction half-reaction represents the species gaining electrons (reduction). By balancing the number of electrons transferred in each half-reaction and combining them, the overall balanced equation is obtained. In this specific equation, zinc is oxidized