What causes the generation of oxygen in a PbS and H2O2 reaction?

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Discussion Overview

The discussion revolves around the generation of oxygen in the reaction between lead sulfide (PbS) and hydrogen peroxide (H2O2). Participants explore the mechanisms of oxidation, the role of acidic conditions, and the solubility of sulfides in this context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how sulfur gains oxygen in the reaction, noting a lack of half-reactions that show oxygen ion generation.
  • Another participant suggests that sulfides can be oxidized by roasting in air, questioning the necessity of "oxygen ions" for the reaction.
  • A participant proposes that electrons from PbS are needed to initiate the reaction, suggesting a half-reaction where PbS becomes PbS(2+) and releases electrons, allowing H2O2 to act as an oxidizing agent.
  • There is a question raised about the requirement of an acidic medium for the reaction and its implications for the oxidation process.
  • Participants discuss the solubility of sulfides and the potential effects of acidity on shifting the dissolution equilibrium.
  • One participant questions the relevance of dissolution to the reaction, while another notes that reactions in the liquid phase tend to occur more rapidly.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the mechanisms involved in the reaction or the necessity of acidic conditions. Multiple competing views regarding the oxidation process and the role of solubility remain present.

Contextual Notes

The discussion includes uncertainties about the specific half-reactions involved, the role of acidity in the reaction, and the implications of solubility on the reaction dynamics.

Vriska
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I don't get it, how did the sulfur get an oxygen, I'm unable to find any any half reaction wherein a oxygen ion is generated. So what is happening here?
 
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You can oxidize sulfides just by roasting them in the air, there is no solution, no ions there at all. Why do you think you need "oxygen ions" for anything?
 
Borek said:
You can oxidize sulfides just by roasting them in the air, there is no solution, no ions there at all. Why do you think you need "oxygen ions" for anything?

Idea was that you'd need electrons first from PbS to start the reaction. you'd have some PbS -> PbS(2+) + 2e. Now you could have H2O2 accept electrons as an oxidising agent. But nowhere I'm seeing any half reaction that could put an oxygen there and plug that +2 charge.

But now you put it that way, it looks like simple burning. But why is acidic medium required there then? what if bubble carbon monoxide through hydrogen peroxide can I expect CO2, will this be as exothermic as burning CO?
 
Vriska said:
But why is acidic medium required there then?

What do you know about solubility of sulfides? Can you think about a way of shifting the dissolution to the right?
 
Borek said:
What do you know about solubility of sulfides? Can you think about a way of shifting the dissolution to the right?

I'm unafraid i don't follow, PbS is apparently quite insoluble in water. I'm not sure how acid will help unless there's an hydroxide on the right side which will be eaten by the acid.
 
What about protonating S2-?
 
Borek said:
What about protonating S2-?

Woah, amazing. thank you!
 
Borek said:
What about protonating S2-?

Heyyyyy wait a second what does dissolution have to do with this reaction?
 
Reactions in the liquid phase are much faster.
 
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