Oxidation Reduction (redox) Balancing

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SUMMARY

The discussion centers on balancing oxidation-reduction (redox) reactions in acidic and basic environments, specifically addressing the addition of H+ ions and H2O in acidic conditions, and OH- ions and H2O in basic conditions. It is established that H+ ions can react with oxygen to form H2O, while OH- ions can also contribute to water formation. The use of hydronium ions (H3O+) instead of H+ ions is suggested for clarity in acidic reactions. An example reaction involving permanganate and iodide illustrates the balancing process and the role of water in these reactions.

PREREQUISITES
  • Understanding of oxidation-reduction (redox) reactions
  • Familiarity with acid-base chemistry
  • Knowledge of half-reaction method for balancing equations
  • Basic principles of chemical equilibrium in aqueous solutions
NEXT STEPS
  • Study the half-reaction method for balancing redox reactions
  • Learn about the role of hydronium ions (H3O+) in acid-base chemistry
  • Explore the impact of pH on redox reactions in aqueous solutions
  • Investigate the use of oxidation states in balancing chemical equations
USEFUL FOR

Chemistry students, educators, and professionals involved in chemical reactions, particularly those focusing on redox processes in various pH environments.

krackers
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When balancing oxidation reduction reactions involving acids or bases, what (in the case of acids) allows you to add H+ ions to one side of the reaction and H2O to the other, or in the case of bases, OH- and H2O to balance out hydrogen/oxgen? Normally you are not allowed to just add random compounds to either side of the equation.

I suspect this has something to do with the ability of H+ to grab oxygen atoms to form H2O, as similarly with 2OH- to supply Oxygen atoms and give H2O, as demonstrated by these two reactions:
2H^{+}\; +\; O^{2-}\; -->\; H_{2}O

2OH^{-}\; -->\; H_{2}O\; +\; O^{2-}

However, is this the real reason? And instead of using H+ ions for the acids, wouldn't it be more appropriate to use the hydronium ion, H3O+?In case the question is not clear, here is an example reaction.

MnO_{4}^{-}\; +\; I^{-}\; -->\; I_{2}\; +\; Mn^{2+}

One of the half reactions would be:

5e^{-}\; +\; MnO_{4}^{-}\; +\; 8H^{+}\; ->\; Mn^{2+}\; +\; 4H_{2}O

However, in this half reaction what allows you to add H+ to one side and H2O to the other?
 
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These reactions usually take place in water, and typically in either low or high pH - so you can safely assume there is plenty of H2O and H+/OH- around. As there is plenty of them, they can be between reactants and products and you won't even notice changes in their concentrations.
 

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