question about solubility of NH3

[pandalove89]

The question is:
Which of the following compounds would be most soluble in NH3?

1. K2CO3
2. NaBr
3. AgBr
4. CaCl2
5. LiNO3


I was confused so I thought it would be 5, since they both have Nitrogen, so it would be a common ion solubility rule or something.

However the answer is 3. The explanation is: transition metals have a particular tendency to form complex ions. For example when NH3 is added to AgBr a complex ions forms Ag(NH3)2+.

How can we randomly assume that the transition metal would be the most soluble though...?

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[pandalove89]

bump

 

[LetsGo2DSchool]

I remember this question in Destroyer and wondered too about how does one go about figuring this out. I hope they don't ask a question like this.

 

[bharat008]

I usually think of this as acid/base rxn. NH3 is basic so acidic salt would be more soluble in it. Now we know that alkali/alkaline cations are neutral while the transition metals are acidic. Therefore, Ag cation would be acidic and tend to be more soluble in NH3..

Hope that helps..

 

[soosoolhastam]

Bharat008 got it. AgBr dissociates to Ag+ & Br-. The positively charged silver is acidic. Because bases are more soluble in acid AgBr will be more soluble in NH3. All other ionic compounds with the exception of 1 would result in a neutral solution.

 

[spoog74]

The question is:
Which of the following compounds would be most soluble in NH3?

1. K2CO3
2. NaBr
3. AgBr
4. CaCl2
5. LiNO3


I was confused so I thought it would be 5, since they both have Nitrogen, so it would be a common ion solubility rule or something.

However the answer is 3. The explanation is: transition metals have a particular tendency to form complex ions. For example when NH3 is added to AgBr a complex ions forms Ag(NH3)2+.

How can we randomly assume that the transition metal would be the most soluble though...?

let me give this a shot with what chad taught me...

The NH3 is a base.... obviously.. So you're looking for an acid..... or the most acidic acid.... because acids are most soluble in bases and vice versa.. So .... When you dissociate everything there just compare it with water.... OH and H so you get down to Ag Br and you do H and OH so yo get HBr and AgOH and there you see HBr is a strong acid, thus NH3 is most soluble in this solution. If you try this with any other answer choices, you wont get a strong acid alone, youll get either a strong acid and strong base, or a weak acid weak base etc etc..

For example if we compared O and OH to the other choice NaBr we get NaOH <--- strong base, and HBr, strong acid but these will both neutralize each other. Thus it wont work ! Doing this with every answer choice comes down to AgOH <-- weak base and HBr <--- strong acid 🙂

 

[Bis-GMA111]

i also used chad's logic here...


we know that NH3 is going to accept a proton to form NH4+ (hence a base), so we are looking for an acidic salt...

CO3(2-) is a base, and potassium is a negligible metal therefore this is a basic salt

sodium is negligible and br is negligible-->neutral salt

ag is acidic, br is negligible-->acidic salt

Ca is negligible, cl is negligible-->neutral salt

lithium is negligible, NO3 is negligible-->neutral salt

therefore, the only acidic salt among these choices is AgBr, making this the correct answer. Hope this helps