Why is Sulfur Mentioned in Qualitative Analysis of Hg+2 and Cu+2?

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Discussion Overview

The discussion revolves around the role of sulfur in the qualitative analysis of mercury (Hg+2) and copper (Cu+2), specifically in the context of their separation using 3M nitric acid (HNO3). Participants explore the reasoning behind the presence of sulfur in this analysis.

Discussion Character

  • Homework-related, Conceptual clarification

Main Points Raised

  • One participant states that the answer to a homework question is that HgS is less soluble than CuS in 3M HNO3, but expresses confusion about the presence of sulfur in the solution.
  • Another participant suggests that the confusion may stem from an omission regarding the precipitation of sulfides, specifically mentioning "following precipitation with H2S."
  • A later reply acknowledges the oversight regarding the sulfur atom's role in the analysis.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the understanding of sulfur's role, as there is confusion and an acknowledgment of an oversight regarding the process involved in the qualitative analysis.

Contextual Notes

The discussion highlights a potential missing assumption about the precipitation process involving H2S, which is not explicitly detailed in the initial post.

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Homework Statement


In qualitative analysis, Hg+2 can be separated from Cu+2 by the addition of 3M HNO3 because

A. Cu(NO3)2 is less soluble than Hg(NO3)2
B. Hg(NO3)2 is less soluble than Cu(NO3)2
C. HgS is less soluble than CuS in 3M HNO3
D. CuS is less soluble than HgS in 3M HNO3
E. Hg+2 is oxidized by 3M HNO3, whereas Cu+2 is not

Homework Equations


-

The Attempt at a Solution


The answer is C but I don't understand how there is a S atom in the solution. Is there something I am missing?

Thanks!
 
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You're certain you haven't omitted "following precipitation with H2S?"
 
Yep
 
We'll mark that down to an "oversight."
 
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Ok thanks!
 

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