Half-Reactions in Zn + HCl Reaction

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    Hcl Reaction
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Discussion Overview

The discussion revolves around the concept of half-reactions in the context of the reaction between zinc and hydrochloric acid (Zn + HCl). Participants explore the definitions and applications of half-reactions in oxidation/reduction processes, as well as the implications of oxidation states in the reaction.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant requests clarification on half-reactions for the reaction between Zn and HCl.
  • Another participant provides half-reactions, stating that Zn is oxidized to Zn2+ while HCl is reduced to H2 and Cl-.
  • A similar response is reiterated by a different participant, emphasizing the electron transfer involved in the half-reactions.
  • A question is raised regarding whether hydrogen is being reduced or if the entire HCl compound is undergoing reduction, highlighting the complexity of identifying which part of a compound is affected in redox reactions.
  • A participant argues that in aqueous solutions, Cl- acts as a spectator ion, suggesting that H+ is the reactive species, while also noting the challenges of attributing oxidation states to specific atoms within compounds.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of half-reactions and the role of individual elements versus whole compounds in redox processes. The discussion remains unresolved regarding the specific identification of which component is reduced.

Contextual Notes

Participants acknowledge the limitations of using oxidation numbers as a mere accounting tool for electron transfer, which may not reflect measurable properties of atoms in compounds.

Kaneki123
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I do not have a clear concept about half-reactions...Can someone please give the half reactions for following reaction,
Zn^0 + 2H^1 Cl^-1 -----> Zn^+2 Cl2^-1 + H2^0
or Zn + HCl ----> ZnCl2 + H2
 
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"Half reaction" is used when you have to deal with oxidation/reduction reactions. Half reaction represents how electron is produced/consumed for reducing and oxidizing agent. So,
Zn = Zn2+ + 2e-
2HCl + 2e- = 2Cl- + H2
Add both equation and you will see.
 
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HAYAO said:
"Half reaction" is used when you have to deal with oxidation/reduction reactions. Half reaction represents how electron is produced/consumed for reducing and oxidizing agent. So,
Zn = Zn2+ + 2e-
2HCl + 2e- = 2Cl- + H2
Add both equation and you will see.
Also one more thing...In the given equation, the oxidation state of H is changed...So would we say that H is being reduced or its whole compound HCl is being reduced?
 
In water Cl- is just a spectator, it is H+ that reacts.

But in the gas phase, where only HCl is present I am ready to accept your statement as a correct. Pointing to an element in a compound and stating "this is what is being reduced/oxidized" is often questionable, as it is whole molecule/ion that undergoes the reaction. Yes, when we use oxidation numbers for redox reactions that how we think about the process, but oxidation numbers are just a accounting device designed for keeping track of electrons in the reaction. There is no property of an atom that we can measure to check its oxidation number.
 

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