Summary of Balancing Redox Reactions

[Jack_Pearce_2H]

Can somebody give a brief summary on the process to balance a redox reaction in a galvanic cell? I just want to make sure I have the right through process for how to approach these problems. Thanks!

[HilaGelfer_2H]

Hi,

In general when balancing redox reactions you must first divide the reaction into the reduction and oxidation half reactions. Afterwards, you must balance each half reaction based on the acidic/basic conditions mentioned. In each half reaction make sure to include the number of electrons gained or lost. After balancing each half reaction, if necessary multiply one of the half reactions to ensure that each half reaction loses/gains the same number of electrons so they can cancel. Afterwards you can add the half reactions to get the redox reactions. Also, on Dr Lavelle's Website he has two links/summaries for balancing redox reactions under both acidic and basic conditions.

I hope this helps :)

[Sera Aintablian 2E]

*In a galvanic cell, energy released by spontaneous redox reactions is converted to electrical energy.

Step 1: Identify the oxidizing and reducing agents, and write out their half reactions.
(Oxidation: loses electrons, increased oxidation number (charge), Reduction: gains electrons, decreases oxidation number).
Step 2: Indicate which electrode is the cathode and which is the anode (electrode with more negative standard reduction potential value becomes the anode (switch the sign), because a galvanic cell must have a positive standard cell potential value (spontaneous).
Step 3: Balance the half reactions (first the elements before H and O). If the solution is acidic, balance the reactions with H+ ions and H20; if basic, balance the reactions with OH- hydroxides and H20.
Step 4: Balance the charges on both sides of the reaction (the charge does not have to equal zero: just equal on both sides). Both half reactions should have the same number electrons lost/gained, so they cancel out in the final balanced equation.
Step 5: Combine your half reactions, cancel out your electrons, and simplify if you can. Make sure everything is balanced!