Mistake in TBR?

[SonhosDaVida]

In this question, shouldn't it read least soluble in which solution?

Since NO3 so readily dissociates, there is a bigger abundance of NO3 ions already present in solution, thus according to common ion effect, this reduces the solubility of Hg(NO3)2.

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[SweetBurger]

Think of somehow you only have Hg^2+ ions and you add them to each one of the listed solutions in the answer choices. Its not really a common ion effect question as much as it is a pure solubility rules recall question. Given the fact that the NO3 is infinitely soluble in water it isn't going to recombine with the Hg^2+ ions and hence no Hg(NO3)2 wont precipitate out of solution making Hg^2+ the most soluble in this solution. In the case of the other solutions (example NaCl) the Cl is far less soluble than NO3 and therefore a significant degree of HgCl2 is going to precipitate out of solution. Does that make sense?

 

[SonhosDaVida]

Thanks for the explanation. So basically is this question saying that Mercury cation will combine with the given salt, NaCl, NaNO3, etc to form HgCl2 or HgNO3)2 and then, asking the solubility of the newly formed salt products such as HgCl2 or Hg(NO3)2? Thanks

 

[SonhosDaVida]

Also, compared with NaNO3, Hg(NO3)2 is less soluble, so it will precipitate out of solution (like in an ion exchange column.)

Same for the HgS, HgCl2, HgI2 compared with Na2S, NaCl, snd N'ai, respeftively right? Since Hg salts are not as soluble as sodium salts, intrinsically?

 

[SweetBurger]

Thanks for the explanation. So basically is this question saying that Mercury cation will combine with the given salt, NaCl, NaNO3, etc to form HgCl2 or HgNO3)2 and then, asking the solubility of the newly formed salt products such as HgCl2 or Hg(NO3)2? Thanks

Yes exactly.

Also, compared with NaNO3, Hg(NO3)2 is less soluble, so it will precipitate out of solution (like in an ion exchange column.)

Same for the HgS, HgCl2, HgI2 compared with Na2S, NaCl, snd N'ai, respeftively right? Since Hg salts are not as soluble as sodium salts, intrinsically?

Yes, the Hg salt is less soluble than the sodium salt and some Hg(NO3)2 may precipitate out of solution, but it is still relatively soluble. For this questions its really important to note that combinations of Hg with Cl, I, or Sulfides is significantly less soluble than with Nitrates.