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Balancing Redox Equations• Many redox reactions are too complex to
simply balance by inspection we must ensure that the e- lost and gained balance
• There are 2 methods to balance redox rxn:– Half reaction– Using oxidation numbers
Half Rxn Method
We’ll balance:Sn + HNO3 SnO2 + NO2 + H2O
• Step 1: Assign oxidation numbers to each element to identify which is oxidized and which is reduced.
• Step 2: write the half rxn, using only elements that change in oxidation number. Then add e- to balance the charges.
• Step 4: Transfer the coefficients into the original reaction.
• Step 5: Balance the remaining elements by inspection.
• Step 6: Check the equation to see that it is balanced.
Balancing Acid/Base Solutions• We follow the same steps as before, but leave
the H and O until the end, and then balance by adding H+, OH- or H2O according to:
• In acid solutions, we add H+ and H2O as needed
• In basic solutions we add OH- and H2O as needed