Aspirin Questions: Seeking Guru Input

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these questions were given to us to think 'bout for homework. I thought about the answers but I'm thinking i may be a bit wrong for some? i don't know .. if someone has an extra 2 minutes i'd appreciate their guru imput.

a)
stomach acid has a pH of about 1.5. Given the acidity of the stomach acid, would Aspirin dissolved in stomach acid be mostly in its ionized or un-ionized form?

For this I figured that aspirin is a weak acid and therefore doesn't fully ionize, in fact i think it's mostly in its molecular form. so, it must be in it's un-ionized form most, right? what i don't get about this is how they ask you to take into account the stomach's acidity ... ? anyone?


b) Un-ionized aspirin molecules can readily penetrate the stomach lining into a region of less acidity, this is where the stomach irritation associated with aspirin occurs. use le chatalier to explain.

for this i assume that since the pH is higher, then the equilibrium shift of the reaction would shift to the right and more H+ will be made, which is of course acidic, and it makes the new regions acidic, and therefore it irritates.


thanks guys!

 

[FZ+]

what i don't get about this is how they ask you to take into account the stomach's acidity ... ? anyone?

I suspect it is an equilibrium thing. Low pH = big H+ concentration, which would push the equilibrium with regards to the aspirin molecules a certain way...

for this i assume that since the pH is higher, then the equilibrium shift of the reaction would shift to the right and more H+ will be made, which is of course acidic, and it makes the new regions acidic, and therefore it irritates.

Exactamondo!