Balancing Redox Reactions: Confusion with Half-Reaction Electron Count

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Discussion Overview

The discussion revolves around balancing redox reactions, specifically focusing on the half-reaction involving chlorate ion (ClO3−) and its electron count. Participants are examining the charge balance in the half-reaction and addressing confusion regarding the number of electrons involved in the process.

Discussion Character

  • Homework-related
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions why the half-reaction ClO3− + 6H+ + 6e− → Cl− + 3H2O has a total of 6 electrons instead of 5, suggesting confusion over the charge balance.
  • Another participant asserts that both sides of the half-reaction have a charge of -1, implying that the reaction is balanced as presented.
  • A different participant expresses uncertainty about the charge contributions, suggesting that 6H+ and ClO− should result in a total of 5 electrons, indicating a misunderstanding of how charges are counted.
  • One participant clarifies that ClO− should be considered as contributing an extra electron rather than a deficiency in the charge balance.
  • There is a question raised about the charge carried by 6H+, with one participant seeking clarification on its contribution to the overall charge.
  • A later reply indicates a realization that the 6 electrons relate to the change in the oxidation state of chlorine, acknowledging that the -1 charge does make sense in the context of the half-reaction.

Areas of Agreement / Disagreement

The discussion reflects a lack of consensus, with multiple viewpoints on the charge balance and the number of electrons involved in the half-reaction. Participants express confusion and differing interpretations of the charge contributions.

Contextual Notes

Participants' understanding of charge balance appears to depend on their interpretations of the contributions from H+ ions and the chlorate ion, which may not be fully resolved in the 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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