Question

When aqueous solutions of ________ are mixed, a precipitate forms.

Answer 1

Answer:

A) NiBr₂ and AgNO₃  

Explanation:

We can use the solubility rules to decide which reaction gives the precipitate.

The important ones for this problem are:

1. Salts of Group I elements and of ammonia are soluble.  
2. Nitrates are  soluble.
3. Halides are soluble. Important exceptions the silver halides.
4. Most sulfates are soluble.
5. Most hydroxides are slightly soluble.

The possible products from each reaction are

A) Ni(NO₃)₂ and AgBr; B) NaBr and KI; C) KCl and Cr₂(SO₄)₃

D) KNO₃ and Ba(OH)₂; E) LiI and Cs₂CO₃.

A) Ni(NO₃)₂ and AgBr

Ni(NO₃)₂ — soluble (Rule 2)

     AgBr — insoluble (an exception to Rule 3)

When aqueous solutions of NiBr₂ and AgNO₃ are mixed, a precipitate forms.

B) NaBr and KI

NaBr — soluble (Rule 1)

    KI — soluble (Rule 1)

C) KCl and Cr₂(SO₄)₃

        KCl — soluble (Rule 1)

Cr₂(SO₄)₃ — soluble (Rule 4)

D) KNO₃ and Ba(OH)₂

   KNO₃ — soluble (Rule 1)

Ba(OH)₂ — soluble (Rule 5)

E) LiI and Cs₂CO₃

       LiI — soluble (Rule 1)

Cs₂CO₃ — soluble (Rule 1)