The pH Levels of Various Types of Soda Pop

The experimenter

Researched by Marshal N.


The purpose of this experiment was to determine the pH level in various types of soda pop.

I became interested in this idea when I was drinking a soda and I wondered what caused its tart taste and acidy fizz.

The information gained from this experiment could help consumers know what kind of soda pop to buy that won’t destroy their bone calcium and tooth enamel as much as others.


My hypothesis was that colas like Coca-cola or Pepsi would have lower pH than the other pops.

I based my hypothesis on a website by Bob Peebles at that said, “Coca-Cola classic is the most acidic beverage at around 2.5-4.2.”


The constants in this study were:
  •  Temperature of pop
  • The amount of soda-pop in each container
  •  The type of pH measuring meter
  •  Container the soda is put in
  •  How long the meter is put in the soda
  •  Type of container the pop was held in

The manipulated variable was the kind of soda pop.

The responding variable was the pH level.

To measure the responding variable I used a digital pH-measuring meter.

3 12 oz. (355 ml.) Coca-Cola
12 oz. (355 ml.) Pepsi cola

12 oz. (355 ml.) Mountain Dew
3 12 oz. (355 ml.) Sprite
12 oz. (355 ml.) Orange soda
3 12 oz. (355 ml.) Root Beer
1 pH meter
Measuring cup (ml)


1. Collect items for experiment.
a. Three cans each of Coca-Cola, Pepsi, Mountain Dew, Sprite, Orange soda, and Root Beer.
b. Digital pH measuring meter
c. Measuring cup (ml)
2. Label each group of three pops a-f.
3. Take a can from group A and measure out 100 ml. of the pop in a measuring cup.
4. Next put pH meter in the soda pop that’s in the measuring cup and wait for about ten seconds. After the numbers stop changing, read meter. Record data.
5. Triple test each can, so do this test two more times.
6. Repeat step 3 - 5 for the rest of the cans in-group A.
7. Average the results for all the cans in this group.
8. Repeat steps 3 - 7 with another group like B.
9. Repeat steps 3 - 7 for the rest of the groups C - F.


The original purpose of this experiment was to find the pH levels in various types of soda pops.

The results of the experiment were that Root Beer had the highest pH at 4.24 followed by Sprite at 3.29 and Mountain Dew at 3.27.  The lowest scores were Orange at 2.90, Pepsi at 2.61, and the one with the lowest pH was Coca-Cola at 2.52.

See the table and graph below.


My hypothesis was that colas like Coca-Cola or Pepsi would have lower pH than the other pops.

The results indicate that this hypothesis should be accepted because Coca-Cola and Pepsi had lower pH than all the other pops.

Because of the results of this experiment, I wonder if the amount of carbonation would affect the amount of pH.  For example, if the pop was forced to be “flat” would that affect the pH.

If I were to conduct this project again I think I should use the reference solution for the pH meter more often to make sure it was still reading right during the experiment.

I also could have tested more brands of pop to tell the pH of other pops that people might like, for example Shasta pops and Sam’s Choice.

I should have tested different types of pop like Mountain Lightning, which is almost the same as Mountain Dew and I should have checked for a difference.


One really important health need of humans is healthy bones.  When consumers drink pop with very low pH it affects their bone calcium.

Bones are made by body cells.  Bones are living organs.  That’s why bones can mend themselves and make blood.  Bones are always making new cells.  To do this calcium is stored in bones through the blood.  When you are young you grow quickly that’s why kids need a lot of calcium.   It is vital that kids eat calcium-enriched foods and not pop.  In later life you don’t need as much.  Calcium carbonate makes teeth hard.  If the outer layer of a tooth called the enamel is destroyed it can’t be replaced.

Bone Calcium
When people drink pop it robs bone calcium.  The bone calcium is turned into alkaline by your body to neutralize the pH in pop.  Humans need calcium for bone growth and strength.  Pop robs the calcium you need for your skeletal system.  If you don’t have calcium, your bones can get weak and you can get hurt more easily.

In isolation calcium is really a metal.  The most common compound is calcium carbonate.  Bones of animals and humans have calcium in them.   One-fifteenth of the human body is calcium.  Calcium is never found on it’s own because it reacts with other elements easily.  Limestone is the most common calcium holder.  Calcium is precipitated in springs because it isn’t stable in hot water.  Building stones have calcium in them.  Calcium oxide is in cement or in concrete known as quicklime.  Calcium hydroxide is hard and white.

The pH is a number showing the amount of hydrogen ions in a solution.  pH stands for potential hydrogen.  The scale is 0-14.  Something with a pH level of 7 is totally neutral, neither acidic or basic.  Distilled water has a pH around 7. A pH of 0 to almost 7 in the scale is acidic.  From 7 to 14 is alkaline on the scale.  A pH lower than 3 can give brain damage to people.  Human blood is about 7.4 pH. 

The pH is expressed as moles of hydrogen ions per liter.  A pH solution with 6 is 10-6 (or one millionth) of a mole of hydrogen ions.  A chemist Soren Sorenson made the pH system in 1909.  There are about two ways of measuring pH.  One way is with a pH meter or using special strips that change color depending on amount.

Phosphoric Acid
Phosphoric acid is one of the acids in soda pop; its formula is H3P4.  Phosphoric acid is also called orthophosphoric acid. This acid is very soluble (dissolves) in water and alcohol.  It is made from phosphate and sulfuric acid.  It also melts at 42.4° Celsius.  This acid is also helpful as a water softener.  

Citric Acid
Citric acid is another acid in pop.  It is a very weak acid if it wasn’t it could take a couple teeth out.  Its formula is C6H8O7.  Citric acid is in many fruits that are commonly known as citrus fruits like oranges, limes, lemons, and many others.  The citric acid in fruit is what gives fruit sourness.  It is also found that molds can produce this acid.  This acid melts at 153° Celsius.  Citric acid shares the same properties as carboxylic acid.  Citric acid is used for flavoring such as in pop.  Citric acid is what gives fruit tartness.   Citric acid is also used as water softener.  Citric acid is popular as a buffer.  

Carbonic Acid
Carbonic acid is made from carbon dioxide and water mixed which equals the formula H2O + CO2 = H2CO3.  It is also impossible to get pure carbonic acid.  To get carbonic acid; carbonation in pop it is pushed in at 250-550 kilo pascals.

Soda Pop

 A soft–drink is a flavored, non-alcoholic, carbonated drink.  Soft drink indicates that pop is not an alcoholic drink.  On average people drink about 56 gallons a year.  Joseph Priestly made the first carbonated drink.  In 1772 a British scientist found a way to force carbon dioxide into water.  That’s what carbonated water is.  This led to the soft-drink industry.  In the 1820’s soda was first put in refillable bottles.   In 1905  the crown cap was first used for bottles.      

Coca-Cola is called the world’s greatest soft drink.  John Pemberton made the original formula for Coca-Cola.  Pemberton’s partner made the name “Coca-Cola” because he liked two C’s.  It was a tonic for headaches and tiredness.  He sold 25 gallons for $50.  Their slogan was “Delicious and Refreshing.”  One day someone spilled carbonated water in the mix and everyone liked it better.  Soon he sold the business to a man named Asa Candler for $2,300 because of health. 

Candler made Coke very popular in the United States.   His slogan was “Nerve and Brain Tonic.”  He advertised Coke on calendars and many other things.  Mr. Candler didn’t like bottling but let a fountain owner do it so he could sell to people out of the city.  Many tried to copy the drink.  There were 150 imitators.  In 1915 Asa hired a man to make a curved glass like a bell.   In 1919 Candler sold Coca-Cola to a group of investors for $25 million.  They elected Robert W. Woodruff as president of the company.   In 1920 Woodruff had cola put in vending machines so people could get one for themselves.  Today the Coca-Cola company produces many other products like Sprite.

 Here are some interesting facts:
∑ Mexico and Iceland have the highest per capita consumption of Coca-Cola.
∑ Every second over 7,000 Coca-Cola products are consumed.
∑ If all the Coca-Cola vending machines in the U.S. were stacked one on top of each other, the pile would be over 450 miles high.
∑ This is what’s in Coke:  carbonated water, high fructose corn syrup, caramel coloring, phosphoric acid, natural flavors, caffeine.

Pepsi Co, Inc. is a big company.  Bottles are shipped around the world.  In 1889 Caleb Bradnem made the first Pepsi drink.  It was originally made to cure dyspepsia.  Caleb formed the Pepsi Company in 1903.  He bottled the product and filled drugstores with it.  In 1923 Bradnem filed for bankruptcy because of bad sugar prices.  In 1931 Charles G. Guth bought the company.  Guth increased sales by selling larger bottles.  Pepsi has grown a lot since 1933.  Pepsi became the second best seller in the pop industry.  Former Coca-Cola worker Alfred Steele was Pepsi’s president in 1950.  Pepsi obtained Mountain Dew in 1964.  Pepsi also owns and sells bottled waters, sport drinks, and ice teas. 

Bone calcium is very important to human health.  The pH in pop robs that and tooth enamel.  Pop does that because of all the acids in it.  So if you have a craving for pop you should think about all the harm it can do.  When you lose too much bone calcium you can get hurt.  As a child it is even worse to drink pop because you need more calcium to grow up.  When you drink pop it takes enamel and your tooth can’t replace it so your tooth suffers.


“Acid”. 11/17/04.

Armbruster, David C. “Citric Acid”.Nov.04. <Http;//>.

Barratt, Robert F. “Soft Drink Industry.” Canadian Encyclopedia. 1998.

Busch, A Marriana. “Phosphoric Acid.” World Book Encyclopedia. 1999.

“Carbonic Acid”. Nov. 04. <>

“Carbonic Acid”. 11/24/04. <>

Chamblee, Theresa S. “Soft Drink”. 20, Oct. 2004.  <>.

“Citric Acid.” 17 Nov. 04 <>.

“Citric Acid”. 12/1/04.

Columbia University Press. “Phosphoric Acid” <>.

“Coral Calcium”. Soda pH. 11/16/04.

Melissa Maupin. Coca-Cola.  Mankato, Minnesota. Smart Apple Media, 2000.    4-32, 42-48.

“Pepsi Co, Inc”. Encarta. 2005.

“Phosphoric Acid.” The Columbia Electronic Encyclopedia. 2004.

“Phosphorus”. Elements. 1997. Vol.11. Pp.42-50.


I would like to thank the following people for helping make my project possible:
  •  My mom for helping me to do my experiment and supporting me in what I do.
  •  Mr. Newkirk for teaching me things to do and how to improve and also correcting my report.
  •  Melinda Simon for taking two hours out of her time at Tree Top to let me do my experiment.
  • Mrs. Helms for helping me and finding mistakes in my typing.

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