LET'S THINK Phenobarbital (C12 H12 N2Os; M = 232.2g/mol) is a weak acid (pKg = 7.4) used as a sedative and anticonvulsant. This drug is insoluble in water; the concentration of saturated aqueous solutions of this compound is close to 1 g/L pH Homework Unanswered Estimate the pH of a saturated solution of phenobarbital.