Question

Consider these compounds:

A. Pb3(PO4)2

B. Ca3(PO4)2

C. Ag2SO3

D. Mg(OH)2

Complete the following statements by entering the letter(s) corresponding to the correct compound(s). (If more than one compound fits the description, include all the relevant compounds by writing your answer as a string of characters without punctuation, e.g, ABC.)

Without doing any calculations it is possible to determine that silver chromate is more soluble than ___ , and silver chromate is less soluble than ____ .

It is not possible to determine whether silver chromate is more or less soluble than ____ by simply comparing Ksp values.

Answer 1

Without doing any calculations it is possible to determine that silver chromate is more soluble than AB , and silver chromate is less soluble than C.

It is not possible to determine whether silver chromate is more or less soluble than D by simply comparing Ksp values.

Explanation: The predictions can be made by considering hard-soft acid base theory. Since PO₄^3- is a hard base, and Pb²⁺ and Ca²⁺ are both hard acids, their solubility will be less. Hence silver chromate will be less soluble than these. Ag⁺ is a soft acid and SO₃^2- is a borderline base. Hence the solubility will be higher for this. Hence silver chromate is less soluble than silver sulphite.

The solubility product of Mg(OH)₂ and solver chromate are very similar. Hence by comparing these two quantity, it is not possible to predict the solubility.