The pH of Various Soft Drinks
Picture of the Student Reseach Report0

Researched by Sara W.


The purpose of this experiment was to determine the acidity of various soda pops. 

I became interested in this topic when I wanted to know the least acidic soda, because my mom has a sensitive stomach. 

The information gained from this experiment will help people with a digestive problem, to know the soda pop with the least amount of acid. 


My hypothesis is Sprite will be most acidic, and Dr. Pepper will be least acidic.  The order from greatest to least, Sprite, Mountain Dew, Mug root beer, Coca- cola, Pepsi, then Dr. Pepper. 

I base my hypothesis on the answer and the estimation of a chemist, Bob, at S. S. Stiener the hop analyzation and storage company. 


The constants in this study were: 

  • Amount of Soda per test
  • Time opened before testing
  • Expiration date
  • The number of trials
  • The test method

The manipulated variable was the type of soda.

The responding variable was the acidity measured in pH.

To measure the responding variable I used a pH indicator, and a pH meter. 

2 cans of each soda
1 pH indicator
1 pH meter
1 bottle of 7.0 pH reference
1 bottle of 4.0 pH reference


1 Obtain all materials.

2 Label each cylinder one by one for each soda. ( Example: Pepsi1; Pepsi2 )

3 Pour 100ml of the correct soda into each cylinder 

4 Take the indicator meter out of the covered cylinder ( it will already be there with a water in it, LEAVE THE WATER IN IT )

5 Use a set neutral liquid (labeled), then wait for the pH meter to say ready then press yes on the pH meter.

6 Use another set acidic (4.0) reference, then wait for the pH meter to say ready then press yes on the pH meter

7 Start to test the sodas (donít repeat steps 5-6)

8 Slide one of the vials under the pH meter.

9 Then wait for it to stabilize.

10 Go to the pH meter and read the pH meter to say ready.

11 Repeat the steps for each cylinder.

12 Put soda in to the sonicating bath. Be careful that the foam doesnít foam over. 

13 Repeat steps 8-9 for each soda. 

14 Repeat steps 7-13 for each soda.

15 When you are finished put the pH meter back in the covered cylinder with the water.


The original purpose of this experiment was to determined the acidity of various sodas.

The results of the experiment were Coke pH was 2.44, Pepsi pH was 2.46, Dr. Pepper pH was 2.93, Sprite pH was 2.88, Moutain Dew pH was 3.23, and Mug root beer pH was 4.06. 

See table and graph


My hypothesis was Sprite would be most acidic, and Dr. Pepper would be least acidic.  The order from greatest to least, Sprite, Mountain Dew, Mug root beer, Coca- cola, Pepsi, then Dr. Pepper.

The results indicate that this hypothesis should be rejected. 

Because of the results of this experiment, I wonder if I used different sodas if the results would vary extremely. The last thing I would do is see if temperature affects the pH.

If I were to conduct this project again I would find all my results at the same time. I would also take my samples from different cans of soda. I would do more trials. I would also try more types of soda. 

Research Report


 pH scientist measure on a , pH 14 is highly alkali  and pH0 is the most acid.  The most acid that people can handle with out starting to have brain damage is pH3, and you start to have brain damage when the acid enters the skin pores.  7.0 is neutral, 4.0 is acidic, 10.0 is alkali.   The points 4.0, 7.0, 10.0 are what they use to calibrate a pH indicator unit. 

The pH scale

 The pH scale is very important to chemists. The pH scale is logarthmic. One pH unit represents a ten fold change. The average pH scale goes from pH 0 through pH 14. Under 3.0 and itís a dangerous acid.


Acids are substances below 7.0 (7.0is neutral). Acid is a chemical compound; it produces a prickling or burning sensation when it comes in contact with skin.   Some highly acidic foods are safe to eat only if you eat small quantities. When you eat these acidic foods they will have a sour flavor to them. If you put a highly acid substance on a metal object it can dissolve the area it touches.  If you put an acidic substance on blue litmus paper it will turn red. Hydorchloric gastric acid (HCl) is the acid in your stomach.  The point of HCl is to break down any thing you eat.  So acid is important but yet dangerous. 


Neutral is 7.0.  7.0 is the balance point between acidic and alkali.  Neutral is a single number 7.0. Few things are neutral, distilled water is about the only one.  Certain salts are neutral, one of the salts are a mixture of basic and acidic fluids that form a salt. 


Alkali is higher than 7.0 on the pH scale.   It is safer to eat alkali foods under 10.0 in alkali, rather than acidic foods under 3.0.  Alkali compounds are made of six elements they are: Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium. These six elements are in the first periodic table.  Alkali metals salts are used by industry each year. These salts are obtained from mines and used in thing as in glass, paper, soap, and textiles. 


  A base can also be refered to as alkali.  Bases can react with acid and form a salt. Bases gives water a bitter taste, and the container will feeling slimy, or have a slippery feelling.  A base solution would turn red litmus paper blue.


 Neutralization is a chemical reaction when acid and base form a salt.  Neutralization is not acidic nor basic. Neutrlization is when an acidic fluid, and a basic fluid mix and to be neutral or 7.0 and at that moment they will start to form a salt. 


 The stomach is a simple organ in the human body.  Even though the stomach is the simplest organ is one of the most useful.  The human stomach is shaped like a J. the average stomach holds a little over 0.9 liters.  Gland gives off hyclorchloric acid the enzyme pepsin.  The stomach needs acid to help digest the food you eat throughout the day. 


 The average rain falls pH as 5.6 which is only 1.4 more acid hte neutral.  Acid rain is lower, 4.0 to 5.0 which is more acidic then normal.


Barry, Roger D, "Neutralization," The World book Encyclopedia,  1999, page 154

"Base," Academic American Encyclopedia,  1998, page 83

Duward, Shiver F.   "Alkali,"  The World book Encyclopedia , 1999, page 369

Frere, John and Nault, William.   "Acid,"  The World book Encyclopedia  of science Chemistry, Vol 3  1997,  page 136

Frere, John and Nault, William.   "Base,"  The World book Encyclopedia of Science Chemistry, Vol 3  1997,  page 136

Frere, John and Nault, William.   "pH,"  The World book Encyclopedia of Science Chemistry, Vol 3  1997,  page 133

"Hydrogen bond," The World book Encyclopedia of Science Chemistry 1998, Page 135

Rose, Emily Jane   "Acid," The World book Encyclopedia, 1999, page 26

Rose, Emily Jane,   "Base," The World book Encyclopedia,  1999, page 123

Sanford, Gina.  "pH scale,"  Aquarium Owners Guide, 1999.


I would like to thank the following people.  Without the following people my project would not have of been possible. 

  • My mother for transporting me.
  • My family for the encouragement. 
  • Miss Susan Graf at Tree Top food lab for the help. 
  • Mrs. Hostertler for the freedom to do this project my way. 
  • My friends for being so supportive. 
  • My evaluators for grading my project showing me what to fix. 
  • Mr. Newkirk for having me do this project. 


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