Balancing Redox Reactions: Confusion with Half-Reaction Electron Count

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SUMMARY

The discussion centers on balancing the redox reaction involving chromium hydroxide and chlorate ions: Cr(OH)3(s) + ClO3−(aq) ® CrO42−(aq) + Cl−(aq). The participant clarifies the confusion regarding the half-reaction ClO3− + 6H+ + 6e− ® Cl− + 3H2O, specifically the necessity of 6 electrons instead of 5. The participant concludes that the 6 electrons account for the change in oxidation state of chlorine, confirming that both sides of the half-reaction are indeed balanced with a charge of -1.

PREREQUISITES
  • Understanding of redox reactions and half-reactions
  • Knowledge of oxidation states and electron transfer
  • Familiarity with balancing chemical equations
  • Basic concepts of acid-base chemistry, particularly in aqueous solutions
NEXT STEPS
  • Study the principles of balancing redox reactions in acidic and basic solutions
  • Learn about oxidation states and how they change during redox processes
  • Explore the use of half-reaction methods for balancing complex reactions
  • Investigate the role of water in redox reactions and its impact on charge balance
USEFUL FOR

Chemistry students, educators, and anyone involved in chemical analysis or redox reaction balancing will benefit from this discussion.

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Homework Statement



Cr(OH)3(s) + ClO3−(aq) ® CrO42−(aq) + Cl−(aq) (basic)

I am up the point where I need to balance both half-reactions for electron charge and I'm confused as to why this half reaction: ClO3− + 6H+ + 6e− ® Cl− + 3H2O, has a total of 6 electrons instead of 5. Isn't the overall charge on that side +5, from the difference of 6H+ and 1 ClO3-?
 
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Actually both sides of the half-reaction have charge -1. I looked and it looked balanced to me. If it's balanced, why mess with it?
 
Really they are both -1? I thought that 6H+ (6e) + ClO- (-1e) = 5 electrons. Wouldn't all the hydrogen atoms carry a 6+ charge on that side? And on the other side, I see why Cl- + 3H20 = -1. H20 carries no charge and Cl- is obviously -1.
 
ClO- counts as an extra electron, not a deficiency.
 
What about the 6H+? It doesn't carry a charge?
 
Actually, I just realized the 6 electrons were not for total balance charge but rather the change in Cl by itself, so the -1 charge does make sense. Thank you!
 

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