Re: Determining the pH level at which buffered and nonbuffered aspirin dissolve

Jennifer,

Acetylsalicylic acid, or aspirin, as you already know, is more soluble in basic environment than under acidic conditions. This is because the acid becomes deprotonated under basic conditions, forming a carboxylic acid salt. This charged compound is more soluble in water than the acid form of ASA, which is neutral (uncharged).

I suggest you do an experiment in which you add a tablet of painkiller to a series of solutions of buffers of varying pH, ranging from acidic to basic. You can then observe how rapidly the tablets are degraded and become dissolved under these varying conditions. You may well find that, rather than a particular pH determining whether the tablet dissolves or not, pH affects the RATE at which this happens.

I am not aware of the pH in the small intestine, but it is surely much less acidic than the stomach.