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

[TT0]

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

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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!

 

[Bystander]

You're certain you haven't omitted "following precipitation with H₂S?"

 

[TT0]

Yep

 

[Bystander]

We'll mark that down to an "oversight."

 

[TT0]

Ok thanks!