Problem 4.20

Predict whether each of the following compounds is soluble in water

(a)Ni(OH)₂

We need to consult the solubility rules for common ionic compounds in water (table 4.1, page 125 of the text) to answer this question. We see that all hydroxides are insoluble except those of the 1A elements and calcium, barium and strontium. Therefore, nickel (II) hydroxide is insoluble.

(b)PbBr₂

Table 4.1 indicates that bromides are typically soluble. However, there are important exceptions to this rule: that is, bromides of siver (I), mercury (I) ion, and lead (II) ion are insoluble.

(c)Ba(NO₃)₂

Again, from Table 4.1, we see that all compounds which contain the nitrate ion are soluble.

(d)AlPO₄

Insoluble. The only soluble phosphates are those with ammonium ion or an alkali metal as the cation.

(e)AgCH₃COO

Soluble. All acetates are soluble (no exceptions!)