The half-equation method separates the oxidation and reduction of a redox reaction in half reactions. Overall scheme for the half reaction method:

Step 1: Split reaction into half-reactions (reduction and oxidation)

Step 2: Balance the charge or oxidation number with electrons

Step 3: Balance O by adding H₂O

Step 4: Balance H by adding H⁺

Step 5: Multiply by some integer to make electrons (lost) = electrons (gained)

Step 6: Add half equations and cancel substances on both sides

Step 7: (only in basic solution): add OH^- and cancel H₂0

Step 8: Check atom balance and charge balance on both sides of the equation!!!!

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Complete and balance the following redox reactions (skeleton equations) using the half-equation method:

1. Zn(s) + H⁺(aq) ==> Zn²⁺ + H₂(g) (acidic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)

2. I^-(aq) + NO₂^-(aq) ==> I₂ (s) + NO (g) (acidic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)

3. MnO₄^-(aq) + Cl^- (aq) ==> Mn²⁺(aq) + Cl₂(g) (acidic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)

Do same reaction in basic solution:

______________________________________________________ (overall)

4. Br₂(l) ==> BrO₃^-(aq) + Br^-(aq) (basic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)

5. CrO₄^- + S^2- ===> Cr³⁺ + SO₄^2- (acidic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)

6. H₂O₂ + NO₂^- ===> H₂O + NO₃^- (acidic solution)

______________________________________________________ (reduction)

______________________________________________________ (oxidation)

______________________________________________________ (overall)