Balancing Redox

Half Reaction Each redox reaction can be divided into two parts: one for oxidation, the other reduction These parts are called half-reactions Ex. – Break into two half-reactions Ce 4+ + Sn 2+  Ce 3+ + Sn 4+

Balancing Redox Atoms and charges must be balanced Balance the acidic redox reaction below H + + Cl - + Sn + NO 3 -  SnCl NO 2 + H 2 O

Step 1 For Balancing Determine oxidation states for all atoms in the reaction H + + Cl - + Sn + NO 3 -  SnCl NO 2 + H 2 O

Step 2 Show electrons gained and lost using “tie lines” H + + Cl - + Sn + NO 3 -  SnCl NO 2 + H 2 O e - lost 1 e - gained

Step 3 Use coefficients to equalize the electrons gained and lost H + + Cl - + Sn + 4NO 3 -  SnCl NO 2 + H 2 O

Step 4 Balance the rest by inspection 8H + + 6Cl - + Sn + 4NO 3 -  SnCl NO 2 + 4H 2 O

Sample Balance the redox reaction below PbO + NH 3 → N 2 + H 2 O + Pb