Page 133 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1 2024-2025

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

Ksp and Molar Solubility

AgCl has a larger K than Ag CO .Does this mean that AgCl has a larger molar
sp 2 3
solubility than Ag CO ? ………………….WHY?
2 3

No, because they do not have the same number of ions.
For different sparingly soluble salts:

The smaller the value of K the lower the solubility.
sp

This rule is mainly applied for symmetrical salts
and not always obeyed in case of non-symmetrical salts ...................why?

Because of the relative difference in their molar solubilities

So, When comparing the solubilities of two salts, you can sometimes simply

compare the relative values of their K provided that the salts have the same
sp
number of ions (i.e. they are symmetrical in the number of ions)

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