Question

The intrinsic solubility of sulfathiazole, an old antimicrobial, is 0.002 mol/l. it is a weak acid and its pka is 7.12. what is the ph of the saturated solution of sulfathiazole in pure water?

Answer 1

The formula we will use is:

pH = 0.5 (pKa – log C)

where C is the concentration of sulfathiazole in molarity or mol / L

Since all values are given, we can compute directly for pH:

 

pH = 0.5 (7.12 – log 0.002)

pH = 4.91