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Ow, My Tummy Hurts! The Biology and Chemistry of Gas Relief

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Have you ever wondered why bubbles form when you mix soap and water? Is it possible to mix soap and water without making bubbles? Medical doctors actually study similar questions when they treat patients who have too much gas trapped in their digestive system, which can cause pain and bloating and also signal a serious medical problem. Some drugs, including one called simethicone, can help relieve extra gas in the digestive system. In this science project you will find out how simethicone affects bubbles made from soap and water and how this drug helps people with too much trapped gas.


Areas of Science
Time Required
Very Short (≤ 1 day)
Material Availability
Readily available
Very Low (under $20)
You will need to ask an adult helper to cut the chewable simethicone tablets with a knife.

Teisha Rowland, Ph.D., Science Buddies

Thanks to Andrew Bonham, Ph.D., Metropolitan State University of Denver, for feedback on this project.

  • Alka-SeltzerTM is a registered trademark of Bayer Corporation.
  • Pop Rocks® is a registered trademark of Zeta Espacial S.A.


Investigate how the anti-gas drug simethicone can get rid of trapped gas.


Has your stomach ever ached so bad you felt as if it was blown up like a balloon and bloated? You may have had a large amount of gas trapped in your gastrointestinal tract. The gastrointestinal tract, or digestive system, includes your stomach, intestines, and the other organs in your body that work together to digest, or break down, the food you eat so your body can use it.

Everyone has some bubbles of gas naturally in their gastrointestinal tract. Lots of helpful microorganisms, or tiny, microscopic organisms (mostly bacteria and yeast), live inside your gastrointestinal tracts that help your body digest food. When they do, these microorganisms make gas. As the gas bubbles form, they can get trapped within the food being digested.

Although a little trapped gas in the gastrointestinal tract is normal, certain foods and conditions can produce more gas, and large amounts of trapped gas bubbles can cause problems. For instance, some foods with a lot of starch, like beans, broccoli, cabbage, and breads, may be difficult to digest and can make your gastrointestinal tract produce more gas as a result. Additionally, when you are stressed out, your gastrointestinal tract can also make extra gas. You can also trap gas in your gastrointestinal tract by swallowing large amounts of air, such as by drinking quickly, drinking a carbonated beverage, or chewing gum. Lastly, having too much trapped gas can also be a sign of a more serious medical problem, such as having colon cancer. However it happens, when you have too much trapped gas, you are flatulent. If you feel bloated, you are probably flatulent.

To feel happy and healthy, you need the gas made in your gastrointestinal tract to escape your body somehow. As you probably already guessed, you do this by belching (or burping) or by passing gas (or farting). Some medical drugs are made to help people get rid of large amounts of trapped gas. One drug that does this is called simethicone, shown in Figure 1. Simethicone does not prevent gas from being made, but instead it helps your body pass the gas at a faster rate than normal.

Two pink circular tablets
Figure 1. This photo shows two chewable simethicone tablets.

How does simethicone do this? It actually involves surface tension. Surface tension is a complex concept, but for this science project just think about the following example. You may have noticed that it is pretty hard to make bubbles using only water. However, if you add soap to water, you get lots of bubbles. This is because bubbles need just the right amount of surface tension to form. Plain water has too much surface tension for the bubbles to form, but soap decreases the surface tension of the water so that bubbles can form. Simethicone also decreases surface tension, but by a lot more than soap.

In this human biology and health science project, you will investigate how simethicone can get rid of trapped gas. You will do this by testing simethicone in water with liquid detergent. The liquid detergent should normally make bubbles in the water. Similar to the gas bubbles in your gastrointestinal track during bloating. Will the simethicone affect the bubbles? Will they still form in the soapy water? Will they be able to collect and form a layer of bubbles on top of the water, or will the simethicone prevent this? What does the data from your experiment tell you about how simethicone gets rid of trapped gas? Try this science project to find out!

Terms and Concepts



  • Agrawal, A. (n.d.). Introduction to surface tension. Gareth McKinley's Non-Newtonian Fluid Dynamics Research Group. Massachusetts Institute of Technology. Retrieved March 25, 2013.
  • Kids.Net.Au. (n.d.). Flatulence. Retrieved March 25, 2013.
  • Wikipedia contributors. (2013, April 14). Simethicone. Wikipedia, the Free Encyclopedia. Retrieved May 14, 2013.

Materials and Equipment

Experimental Procedure

Testing Simethicone

In this part of the science project, you will investigate how simethicone tablets affect the formation of bubbles in soapy water. This is a model for how simethicone helps get rid of trapped gas bubbles in a person's gastrointestinal track.

  1. In your lab notebook, create a data table like Table 1.
    1. In steps 11 and 12, you will record your observations and results in this data table.
 Jar Do bubbles form in the water?
Do bubbles collect at the top of the water?
Trial 1 With simethicone  
Without simethicone   
Trial 2 With simethicone   
Without simethicone   
Trial 3 With simethicone  
Without simethicone   
Table 1. In your lab notebook, made a data table like this. When you get to steps 11 and 12, record your results in the data table.
  1. Remove two chewable simethicone tablets from their packaging. They may look similar to the ones in Figure 1 in the Introduction, in the Background tab.
  2. Place the tablets on a cutting board and ask an adult to use a knife to cut the tablets into small pieces.
    1. If you want it to be easier to move the crushed tablets to a jar (which you will do in step 4), you can do this on top of a piece of wax paper.
  3. Use the back of a spoon to crush the small pieces into a powder like that shown in Figure 2.
Tablets are crushed into a coarse pink powder
Figure 2. Crush two chewable simethicone tablets into a powder.
  1. Carefully put all of the powder into one of your jars, glasses, or vases, as shown in Figure 3.
    1. Keep track of which jar you put the powder in and which one you did not.
      1. If the tablets are colored, like the ones shown in this Procedure, this should not be hard to do, because when you add water to the powder in the jar, the water should turn cloudy.
      2. Tip: You could put a sticky note with a label (such as "With simethicone" or "Without simethicone") on each jar to help you keep track of them.
An empty glass jar next to a glass jar that contains a small amount of pink powder
Figure 3. Move all of the powdered simethicone into one of the two empty jars.
  1. Fill both jars with water until they are about half full.
    1. Your jars may now look similar to the ones shown in Figure 4.
A glass jar filled with water next to a glass jar filled with a mix of water and pink powder
Figure 4. Fill both jars about half full with water.
  1. Add five drops of liquid dishwashing detergent to both jars.
    1. You are adding the detergent now so that when you add more water in step 8 it will help mix the detergent in each jar.
  2. Fill both jars with water until they are filled about one inch from the top of the jar.
    1. It is important to leave some space at the top of the jars for bubbles to form.
    2. How does the liquid in each jar look now? Does one have more bubbles than the other, or do they look about the same?
  3. Put a clean straw into each jar and stir the water in each jar with the straw.
    1. Make sure that the detergent and simethicone powder is well mixed in the water.
    2. What happens to the liquid in each jar when you stir them?
  4. Get a timer ready or have a clock nearby that shows seconds.
  5. Slowly blow through one of the straws (into the liquid in the jar) for 10 seconds.
    1. Do bubbles form inside of the water? In other words, at the bottom of the straw do you see bubbles come out when you blow through it?
    2. Did bubbles collect, or form a layer, on the surface of the water?
    3. Record your answers in the data table in your lab notebook for the correct jar. This will be Trial 1.
      1. Optional: If you need, or want, to quantify your results for your science fair, use a ruler to measure the height of the foam layer (if any bubbles and foam collect) on the surface of the water. You may want to have a helper do this just as you finish blowing through the straw so that you collect the data before any bubbles pop. Remember that science uses metric measurements, so your data should be in millimeters or centimeters.
    4. If you have a camera, take pictures of your results. You may want to take a picture of the side of the jar, and a picture of the top of the jar. Later you can put these pictures on your Science Fair Project Display Board.
      1. If you do not have a camera, you may want to make drawings of the jar in your lab notebook.
  6. Repeat step 11 with the other jar. Try to slowly blow through the straw just as you did with the first jar.
    1. Be sure to record your answers in the data table in your lab notebook for the correct jar.
  7. Repeat steps 2-12 two more times.
    1. Clean and dry the jars completely before using them again, or use two other clean jars, drinking glasses, or vases that are the same size and shape as each other.
    2. The second time you repeat these steps will be Trial 2, and the third time you repeat them will be Trial 3.
    3. Be sure to record your results in the data table in your lab notebook, writing them down for the correct jar and trial each time.

Analyzing Your Results

  1. Analyze the results you recorded in the data table in your lab notebook. Also analyze any pictures you took or drawings you made of the jars.
    1. Did adding simethicone stop bubbles from forming in the water, or did bubbles still come out of the bottom of the straw?
    2. Did adding simethicone stop bubbles from collecting on the surface of the water?
      1. In other words, did you see a difference in the layer of bubbles at the water's surface of the jar you added simethicone to compared with the jar you did not add simethicone to?
    3. Can you explain your results? If simethicone affected the bubbles, why do you think it did? Hint: For an explanation, you may want to re-read the Introduction in the Background tab.
icon scientific method

Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.


  • In this science project you used two simethicone tablets with a certain amount of water. Do you think if you used one tablet, or part of a tablet, you would still see the effect that you did? Try this science project again, but instead of two tablets use different, smaller amounts of simethicone, such as one tablet, ¼ tablet, 1/32 tablet, etc. You may need to approximate the amount if you use a very small part of a tablet. Ask an adult to help cut the tablets into pieces.
  • You used a straw to create bubbles in soapy water, but you could try making bubbles in other ways, such as by dropping an Alka-Seltzer® tablet or fizzy candy, like Pop Rocks®, in soapy water. Do bubbles made using these different methods look the same? Does simethicone appear to have the same effect on these bubbles?
  • In this science project you used soapy water to test simethicone, but how well does it work in other types of liquid, such as plain water or vegetable oil? Try some to find out!
  • You tested simethicone tablets in water with some detergent in this science project, but this is a bit different from testing simethicone in the liquid that is in your stomach, called stomach acid. Try this science project again, but this time test it in artificial stomach acid. To see how to make artificial stomach acid, check out the Science Buddies project idea Calcium Carbonate to the Rescue! How Antacids Relieve Heartburn. Ask an adult to help you when handling potentially hazardous chemicals and always follow all safety precautions.
  • An adult's full stomach can hold more than two liters. In this science project, you probably used a lot less than two liters of soapy water in each jar. To more closely mimic what happens in a real stomach, repeat this science project using two containers that can hold at least two liters each. Use the recommended dose of simethicone tablets in one of the containers (crushing the tablet[s] as you did before). How effective are the tablets on a full "stomach"? If you used even more water, are they still effective?
  • Think more about how the setup you used in this science project is different from a real stomach and a real digestive system overall. Other than using artificial stomach acid instead of detergent with water, and two liters of liquid total, are there other ways you could change this science project so that it copies more closely what happens in a real stomach? What about changing how thick (or viscous) the liquid is, or adding something similar to digested food? It may be difficult to modify this science project in this way, but if you could change it any way, what changes would you make? To learn more about the digestive system, check out this website:


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MLA Style

Science Buddies Staff. "Ow, My Tummy Hurts! The Biology and Chemistry of Gas Relief." Science Buddies, 20 Nov. 2020, https://www.sciencebuddies.org/science-fair-projects/project-ideas/BioMed_p014/medical-biotechnology/biology-and-chemistry-of-gas-relief. Accessed 30 Sep. 2023.

APA Style

Science Buddies Staff. (2020, November 20). Ow, My Tummy Hurts! The Biology and Chemistry of Gas Relief. Retrieved from https://www.sciencebuddies.org/science-fair-projects/project-ideas/BioMed_p014/medical-biotechnology/biology-and-chemistry-of-gas-relief

Last edit date: 2020-11-20
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