Hands-on Activity: Pill Dissolving Demo

Contributed by: VU Bioengineering RET Program, School of Engineering, Vanderbilt University

Two photos: A girl blowing her nose while sitting in bed next to a table with bottles of prescription medicine on it. A close-up of nine pills of different types, colors and shapes (gel, chalk, pink, green, tablets, capsules, etc.).
In the acidic human stomach, do different pill types dissolve faster than others?
Copyright © (left) 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA. All rights reserved. (right) National Institute of General Medical Sciences, National Institutes of Health http://www.nigms.nih.gov/Education/Factsheet_Drugs.htm


In a class demonstration, the teacher places different pill types ("chalk" pill, gel pill, and gel tablet) into separate glass beakers of vinegar, representing human stomach acid. After 20-30 minutes, the pills dissolve. Students observe which dissolve the fastest, and discuss the remnants of the various pills. What they learn contributes to their ongoing objective to answer the challenge question presented in lesson 1 of this unit.

Engineering Connection

Biomedical engineers use experiments to discover how various chemical substances react in the human body, for example, the absorption of medication and how the body breaks down the outer coatings of pills and capsules. To test new medicines, scientists use solutions with chemical compositions similar to the environments found in the human body to model various body reactions. Engineers also create all sorts of devices and tools used in experiments, and creative medicine delivery materials and equipment, including syringes and patches, and even the factories for making different types of pills and bottling liquids.

Learning Objectives

After this activity, students should be able to:

  • Describe what happens to a pill in the human stomach.
  • Explain which pill form is absorbed the fastest.

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Materials List

For the class demonstration:

  • 3 small glass beakers
  • ~ 2 cups vinegar
  • 3 types of pills: chalk, gel capsule, gel tablet


We have been asked to determine which type of medicine works the fastest.

So many TV and magazine advertisements claim that their medicines offer the quickest relief.

So we are going to do our own experiment to observe three different pill forms to investigate whether the ads are truthful in their claims of offering quick relief, and to determine which type breaks down the fastest in the body.

How does medicine get into the bloodstream? The human stomach is filled with an acidic solution that breaks down all the food and liquid that we ingest.

How long do you think it takes for a pill to dissolve in the stomach? To create a similar environment, we will use vinegar.

Watch the pills carefully. You may be surprised at what happens!


antibiotic: A chemical substance used to treat infections by destroying or inhibiting the growth of bacteria and other microorganisms.

bacteria: Single-celled microorganisms that can exist either as independent organisms or as parasites. Singular = bacterium; plural = bacteria.


Photo shows a glass containing a clear liquid and a chalk tablet sitting next to it.
Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA.

  1. Gather materials on a table that is visible to everyone in the class.
  2. Fill each beaker with approximately one-quarter cup vinegar (or until beakers are half full).
  3. Introduce the demo to students using the information in the Introduction/Motivation section.
  4. Place one pill in each beaker. Note the start time on the clock.
  5. After several minutes, pick up the beakers and observe any change in color of the vinegar. Also, look for any changes in the pills.
  6. Consider a pill fully dissolved when the vinegar is clear (this does not include any remaining outer coverings).
  7. Lead a class discussion. Ask students the Investigating Questions.
  8. At this point, students should be able to determine what form of medicine to take (the shot) for speed. For homework, as described in Assessment section, assign students to write three suggestions of how to make the medicine work more quickly.

Investigating Questions

How does medicine get into the bloodstream? (Answer: Common ways are pills, liquids and shots. Medicines that reach the stomach are broken down so they can enter the bloodstream.)

How long does it take for a pill to dissolve in the stomach? (Answer: Ranges from 15-30 minutes.)

What does this imply about those in liquid form? (Answer: Liquid forms go through the same process as pills once they reach the stomach.)

What happens when you receive a shot? (Answer: The medicine bypasses the digestive process and goes directly into a person's bloodstream.)


Post-Activity Assessment

Short Answer Homework: Assign students to individually answer the following questions with short answers. Review their answers to gauge their comprehension of the subject. Tell the students: Earlier (in the associated lesson), you viewed a short animated video on medicine being injected into the blood stream. We then discussed how long it takes for the medicine in injections, as well as in pills and liquids, to typically take effect. Now, you have just observed an experiment to compare how quickly various types of pills dissolve in acidic environments. With this information, you are now able to answer the first part of the challenge question.

  • Which pill form works the fastest? Why? (Answer: Fastest is chalk, then gel capsule, then gel tablet. This is because it takes longer for the gel coating to dissolve enough for the capsule/tablet to release the inner medicine.)
  • Which form of medicine (pill, liquid or injection/shot) works the fastest? Why? (Answer: The fastest is medicine injected through a syringe [ a shot].)
  • Describe three suggestions of what you might do to get medicine to work more quickly. Provide explanations of why you think they may work. (Answers will vary. Possible answers: 1) move around because increasing your heart rate increases blood flow, 2) eat something because this starts the digestive system, 3) stay warm because this opens the veins more. All of these actions assist your body in absorbing the medicine more quickly, especially pill/liquid forms.)

Activity Scaling

For more advanced students, have them do their own experiments instead of the class demonstration. See the Protect That Pill activity in which students develop pill coatings that can withstand the churning actions and acidic environment found in the stomach. Teams test coating durability by using clear soda to simulate stomach acid.


Michelle Woods


© 2013 by Regents of the University of Colorado; original © 2011 Vanderbilt University

Supporting Program

VU Bioengineering RET Program, School of Engineering, Vanderbilt University


The contents of this digital library curriculum were developed under National Science Foundation RET grant nos. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: April 26, 2017