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The Dissolution Time of Decongestants in Water and Stomach Acid

Researched by Nicole S. 


The purpose of this experiment was to test which allergy nasal decongestant dissolved the fastest in water and simulated stomach acid. 

I became interested in this idea when I would have allergies and I would wonder when the allergy nasal decongestant was going to start working. 

The information gained from this experiment will benefit society by doctors, physicians, and people having the knowledge of when a decongestant is completely dissolved in their stomach.  


My hypothesis was that Sudafed would dissolve fastest in both the simulated stomach acid and water. 

I based my hypothesis on the size of the sinus decongestant compared to the other decongestants.  


The constants in this study were:

  • the amount of water for each tablet
  • the amount of hydrochloric acid and water for each tablet
  • the timers
  • the amount of decongestants in each trial
  • the magnetic stirrer 
  • the place where it was conducted 
  • the temperature of the water (36-37degrees Celsius) 
  • the temperature of the hydrochloric acid (36-37 degrees Celsius) 

The manipulated variable was the types of allergy nasal decongestants added to the water and simulated stomach acid. 

The responding variable was the time that the decongestants took to dissolve. 

To measure the responding variable I used a digital timer.  


Quantity Item Description
1 lab coat
1 pair of goggles
1 pair of latex gloves
2 magnetic stirrers
2.25 L simulated stomach acid
-- water
1 Celsius thermometer
1 Microwave
1 roll of paper towels
2 digital timers
3 beakers
10 tablets of Benedryl
10 tablets of Tylenol
10 tablets of Sudafed



1. Gather all materials needed for experiment.  
2. Wear a lab coat and goggles during experiment. 
3. Obtain 4 liters of 0.01 molar HCl with 0.01 per liter amylase and 0.05 grams per liter of pepsin.  
4. Pour 10ml of hydrochloric acid into a graduated cylinder and then pour what is in the cylinder into the large beaker.  
5. Make sure the temperature of the HCl is 36-37 degrees Celsius.  
6. Get two small beakers and pour 100ml of acid into each.  
7. Set the beakers on the magnetic stirrer. 
8. Add one magnet to each beaker.  
9. Set the speed of the magnetic stirrer to about the center. 
10. Drop in the tablet in one of the beakers and start one of the timers.  
11. Drop in the other tablet (same brand) and start the other timer.  
12. When the tablet is dissolved, stop the timer and magnetic stirrer and record the time.  
13. Empty out the HCl and wash all the materials with water.  
14. Dry the materials with a paper towel.  
15. Repeat steps 2 through 12 four times with each type of decongestant. 
16. Repeat steps 2 through 14 except use water instead of HCl.  


The original purpose of this experiment was to test which nasal decongestant dissolved the fastest in water and simulated stomach acid.

The results of the experiment were that the Benadryl dissolved the fastest in hydrochloric acid and water because of each of the times on it (each had less than 4 minutes).  
View My Data And Graphs 


My hypothesis was that Sudafed would dissolve in the hydrochloric acid and water

The results indicate that this hypothesis should be rejected. 

Because of the results of this experiment, I wonder if the water is stronger than the hydrochloric acid. I wonder what the results would be if I included more medicines such as pain relievers. I also wonder if other temperatures would have different affects. 

If I were to conduct this project again I would use more kinds of decongestants, more trials, and a higher speed to the mixer. 

Research Report


 Acids and bases are part of everyday life. They are in cleaners and other materials. Acids are used in factories for certain reasons. Water too is also very important. Our bodies are made up of 75% of water, in our muscles, brain, and other organs. Water is the key to how animals survive. 

Acids and Bases

 Acids and bases can be classified as organic or inorganic. Common organic acids include citric acid, salicylic acid, carbonic acid, lactic acid, tartaric acid, and hydrogen cyanide. Common inorganic acids would be hydrogen sulfide, hydrogen chloride, phosphoric acid, and sulfuric acid. Sodium hydroxide, calcium carbonate, sodium carbonate, calcium hydroxide, and sodium bicarbonate are common inorganic bases. Acids and bases such as hydrochloric acid and potassium hydroxide (a base) are ionized in water. Strong acids that are in a solution produce high concentrations of hydrogen ions. Acid can be defined as a proton donor. Acids react with metals and other certain materials. Acidity of a solution is measured with a pH scale. Bases are compounds, then break up into OH (hydroxide ions). An acid pH scale is from zero to seven, but bases go from seven to fourteen. Distilled water has a pH level of seven. Dangerous chemicals have low pH levels (near zero) or high pH levels near fourteen. 

Hydrochloric Acid

"A colorless fuming corrosive solution of hydrogen chloride in water," American Heritage Dictionary Hydrochloric acid (HCl) is a strong, dangerous chemical. It is colorless and has an irritating odor. It has many important uses in some industries. Another name for it is muriatic acid. This acid is highly corrosive and is able to cause serious burns. HCl is usually sold as a 30% solution. Dissolving hydrogen chloride gas and water is how it is made. An industry may use HCl for preparing chemical compounds. The stomach secretes little amounts of hydrochloric acid. 


 Allergic reactions can affect many people in many different ways.  Allergens are from allergic reactions by antigens. Examples of allergens include pollens, drugs, lints, bacterias, certain foods, dyes, and chemicals. Lymphocytes are cells that react to antigens. Some allergic reactions take immediate effects. Type one reactions are hay fever, asthma, and insect venom. Type two reactions are a result when antibodies react with antigens. A severe type one is known as anaphylactic shock. 

Sinuses, Sinusitis, and Antibiotic Resistance

 Sinusitis affects about thirty-seven million people per year according to experts. Symptoms of bacterial sinusitis may "copy" colds or allergies. Sinusitis is an infection of sinus cavities by bacteria. They are caused by a cold, allergy attack, or irritation from environmental pollution. Antibiotic resistance is an infection that is caused by bacteria that are immune to effects of certain antibiotics. 


" A homogeneous mixture of two or more substances, which may be solids, liquids, gases, or a combination of these," American Heritage Dictionary 
 A large quantity of a substance in a solution such as water is called a solvent. A  dissolved substance with a small quantity is called a solute. A common solvent is often water. When water is the solvent it is called agueous solution. Solubility will increase when the temperature of the solvent risesin most substances. Certain liquids are capable of dissolving in any proportion of another liquid.  


 As you can see acids can be an important part of life. Our bodies and other living need water too. Water and acid play roles in industry. Different pH levels can be found in an everyday household such as vinegar, soda, and other products. 


 "Acids and Bases are Everywhere." December 11, 2001 

 "Acids, Bases, and pH." December 11, 2001

"Allergies." February 2, 2002 

"Classification." Acids and Bases. December 11, 2001 

"Doctor, What is Sinusitis." February 2, 2002 

Smith, J. Carolyn. "Hydrochloric Acid." The World Book Encyclopedia. 1998. Vol. 9, 

"Solutions." Microsoft Encarta Encyclopedia Deluxe 2001. 2001 ed. CD-ROM. Pg. 465 


I would like to acknowledge the following people for helping me with my project. Without them this project couldn't have been possible.  

  • My mom, Sandra K. for buying me all the trade medicines.
  • Mr. Shotwell, my basketball coach, for allowing me to miss several practices to work on my project. 
  • Mrs. Helms for helping getting the stuff to me and providing helpful advice. 
  • Mr. Newkirk for getting me the simulated stomach acid, and everything else. 


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