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From: "\"Uncle Al\" Schwartz" <>
Newsgroups: sci.chem
Subject: Re: School Child (and Father) need help
Date: Wed, 12 Feb 1997 15:13:45 -0800

Chuck Mugford wrote:

> My 13 year old daughter did an experiment measuring the time it took for
> different brands of non-coated asprin to start disolving in different
> temperatures of water. Now, of course, she wants to know what she was testing.
> Could/would someone please direct us towards the type of reference materials
> we should be looking for? I assume the experiment had to do with with
> solubility(?) and the effects of temperature. Please keep in mind, this is
> only for an eighth grade science class.
> Thanks in advance.

Talk to the FDA or the American Society for Testing Materials (ASTM). 
There are standard assays for tablet disintegration or dissolution

Getting a tablet to survive the world until ingestion and then rapidly
crumble is no small trick.  Once crumbled it can proceed to dissolve. 
Many formulations contain "cross-povidone."  This is a crosslinked
poly(vinyl pyrrolidinone) dust which would be very water soluble if its
molecules were not all welded together.  It is not hygroscopic, but it
swells like a champ in liquid water.

The tablet hits the juice, the polymer swells, everything crumbles, the
greatly enlarged surface area aids in rapid dissolution.

There are other strategies.

Alan "Uncle Al" Schwartz ("zero" before @)
 (Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?"  The Net!

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