Predict which of the following compound will dissolve in the diluted HNO₃ but not in H₂O

[Dhamnekar Winod]

(a) SrCO3 (b)PbBr2 (c)MgF2 (d)MnS (e)Cul (f)Fe(OH)2(g)Hg2Cl2 (h)FeC2O4 (i)PbCl2 (j)CaCrO4

I am working on finding out answers to this question. Any member may provide hint to me.

[ChenBeier]

Carbonate, Hydroxide, Oxalate and Chromate will be dissolved in acid.

[Dhamnekar Winod]

MnS (Manganese Sulphide) and CuI (Copper Idodide) will also dissolve in dilte \(HNO_3\) but not in\(H_2O\)

[ChenBeier]

Manganese sulfid I agree, but copper-I-iodide I disagree. Do you have a proof for it?

[Dhamnekar Winod]

Cuprous Iodide + Nitric Acid = Copper(I) Nitrate + Hydrogen Iodide
\(CuI + HNO_3 \rightleftharpoons CuNO₃ + HI\)

is a Double Displacement (Metathesis) reaction where one mole of Cuprous Iodide [CuI] and one mole of Nitric Acid [HNO₃] react to form one mole of Copper(I) Nitrate [CuNO₃] and one mole of Hydrogen Iodide [HI]

Cuprous Iodide + Nitric Acid = Diiodine + Nitrate Radical + Copper Hydride
\(2CuI + 2HNO_3 \rightleftharpoons I_2 +2NO_3 + 2CuH\)
Two moles of Cuprous Iodide [CuI] and two moles of Nitric Acid [HNO₃] react to form one mole of Diiodine [I₂], two moles of Nitrate Radical [NO₃] and two moles of Copper Hydride [CuH]

[ChenBeier]

Do you use AI, because there is some bullshit in. NO₃ radical under this circumstances and CuH is not existing. Or do you have a link where I can find it.
If CuH would be there your sample would be a small bomb.

[Dhamnekar Winod]

Following link are useful for your reference.

https://www.chemicalaid.com/tools/equat ... O₃+%2B+2HI

https://www.chemicalaid.com/tools/equat ... O₃+%2B+CuH

Author's answer.png (3.78 KiB) Viewed 5196 times

I am sorry. CuI will not dissolve in dilute \(HNO_3\)

Copper(I) iodide (CuI) is **almost insoluble** in water¹. Its solubility in water is extremely low, only about **0.000042 g/100 mL** at 25°C¹. However, it can dissolve in the presence of sodium iodide (\(NaI\)) or potassium iodide (\(KI\)) to form the linear complex anion \([CuI_2]^^-\)¹³. It's also soluble in liquid ammonia, dilute hydrochloric acid, potassium cyanide, or sodium thiosulfate solution².

Source: Conversation with Bing, 1/12/2024
(1) Copper(I) iodide - Wikipedia. https://en.wikipedia.org/wiki/Copper%28I%29_iodide.
(2) Copper(I) iodide - wikidoc. https://www.wikidoc.org/index.php/Copper%28I%29_iodide.
(3) Cuprous iodide | 7681-65-4 - ChemicalBook. https://www.chemicalbook.com/ChemicalPr ... 102056.htm.
(4) Is cui2 ( copper iodide ) Soluble or Insoluble in water. https://www.bengislife.com/2017/11/is-c ... le-or.html.

[ChenBeier]

There not useful, because its redoxreaction which takes place with conc. HNO₃. In the question it was told diluted HNO₃.
Dont use this things, if you dont have knowledge what realy goes on.

[Dhamnekar Winod]

Author said \(MgF₂\) not \(CuI\) will dissolve in dilute \(HNO_3\) but not in \(H_2O\). You didn't say \(MgF_2 , MnS\) will also dissolve in dilute \(HNO_3\) but not in \(H_2O\)

Yes, both \(MgF_2\) and \(MnS\) contain anions of weak acids.

- \(MgF_2\) contains the fluoride ion (\(F^-\)) which is the conjugate base of hydrofluoric acid (\(HF\)), a weak acid¹².
- \(MnS\) contains the sulfide ion (\(S^^2-\)) which is the conjugate base of hydrogen sulfide (\(H_2S\)), also a weak acid⁶⁸.

Remember, the conjugate base of a weak acid can act as a weak base. So, in the presence of a strong acid, these anions can accept protons and form their corresponding weak acids. For example, the sulfide ions from MnS can combine with hydrogen ions from a strong acid like HCl to form a weak acid \(H_2S\)⁶. Similarly, fluoride ions from \(MgF_2\) can combine with hydrogen ions to form hydrofluoric acid⁴.

Source: Conversation with Bing, 1/12/2024
(1) Magnesium fluoride - Wikipedia. https://en.wikipedia.org/wiki/Magnesium_fluoride.
(2) Acid and Base Chart — Table of Acids & Bases - MilliporeSigma. https://www.sigmaaldrich.com/US/en/tech ... base-chart.
(3) The best explanation the solubility of MnS in dil. HCl is that - Toppr. https://www.toppr.com/ask/question/the- ... l-is-that/.
(4) Common Ions and Complex Ions - Division of Chemical Education, Purdue .... https://chemed.chem.purdue.edu/genchem/ ... omplex.php.
(5) Is MgF₂ an acid, base or salt? Explain how you know and ... - Numerade. https://www.numerade.com/ask/question/i ... ing-09938/.
(6) Synthesis and characterization of MgF₂–CoF₂ binary fluorides. Influence .... https://pubs.rsc.org/en/content/article ... c8ra09365b.
(7) Is MgF₂ an acid or base or salt - Bengis Life. https://www.bengislife.com/2017/09/is-m ... -salt.html.
(8) Manganese Sulfide (MnS) Nanocrystals: Synthesis, Properties, and .... https://www.intechopen.com/chapters/52371.

[ChenBeier]

I answered generally., if you check my first answer. MgF₂ is soluble in HNO₃ but also in higher concentration.
I already agreed above that MnS is soluble in nitric acid.
Now stop it please.