Science Buddies: "Ask an Expert"

Hey everyone,
I want to conduct an experiment for my SRP, with the question "What is the effect of stomach acid on the dissolution of pain relieving tablets?" and I want to test 3 different brands (of tablets) in 3 different ph solutions, But I don't know how to carry the experiment out? I don't know what materials I should use and how I should change the 3 ph levels to suit the stomach acidity. it would be great if I could get some suggestions!

I did read somewhere that I should us HCI but I don't know where I can get that or how I change the ph level.
Thanks!

Nitchy

Hi and welcome to Scibuddies. I can answer at least some of your question.

Stomach acid has a pH of 1.5-3.5 and so ordinary distilled white vinegar could be used in place of stomach acid.

In order to test a range of pH's, however, you need some that are lower and some that are higher than vinegar. You mentioned hydrochloric acid, HCl, and that would be a good choice to use for the lowest pH, say 1.0 (0.1 M HCl) or pH 0 (1 M HCl). If your school has a chemistry lab, they will certainly have HCl.

Now, on the other side of the pH scale, you need something that is less acidic than vinegar. You can try diluting vinegar with distilled water or add a small amount of sodium bicarbonate to it.

What you do need--and I should have said this first--is good quality, fresh pH paper that can be read on a scale of pH 0 to 7.0. There are several suppliers online where you can buy a roll of it, or your high school lab should have some.

Let us know if you have more questions,

Sybee