Multiply the two half-reactions by the number that yields the lowest common number of electrons in each half-reaction.Remember that the balanced equations coefficients state the stoichiometric factor or mole ratio of reactants and products. MnO 4 - + 8H + + 5e - → Mn 2+ + 4H 2O 2I - → I 2 + 2e - The balanced equation must now be used to convert moles of Fe (s) to moles of H 2 (g). The second half-reaction has 2- on the left and 0 on the right. Add 5 electrons to the left to balance the charge. In this example, the first half-reaction has a charge of 7+ on the left and 2+ on the right. Now, balance charge by adding electrons as needed.Balance the hydrogen by adding H + as needed: MnO 4 - + 8H + → Mn 2+ + 4H 2O 2I - → I 2.Now add O and H 2O as needed to balance oxygen: MnO 4 - → Mn 2+ + 4H 2O 2I - → I 2.Balance all of the atoms besides the oxygen (O) and hydrogen (H) in the half-reactions: MnO4 - → Mn 2+ 2I - → I 2.Write a skeleton ionic equation that only covers the atoms that change oxidation number: MnO 4 - → Mn 2+ I - → I 2.Find the atoms that experience a change in oxidation number: Mn: +7 → +2 I: +1 → 0.Write down the oxidation numbers for each type of atom on both sides of the equation: Left hand side: K = +1 Mn = +7 O = -2 I = 0 H = +1 S = +6 Right hand side: I = 0 Mn = +2, S = +6 O = -2. First, write the unbalanced chemical equation: KMnO 4 + KI + H2SO 4 → I 2 + MnSO 4.
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