1. The problem statement, all variables and given/known data The rate of degradation of a drug D that is subject to hydrolysis is given by the first order equation rate=kobs (D) where Kobs= Kh (H+) + Ko= Koh (OH-) Derive an equation for the pH at the minimum (pH)min of the pH/rate profile. 3. The attempt at a solution From elementary calculus, I know that I need to first differentiate the rate equation, then find the roots of the differentiated equation. Take a second differentiation of the equation, put the roots into it and see whether it gives a positive or a negative value. The positive value gives you the (pH)min. However...I'm not too sure how to do that with this sort of equation?? Thanks!