Honors Soft Drink Titration Lab
Name:
Soda contains acid. Different acids may be used depending on the type and brand of soda. We want to see which of
the two sodas has the highest concentration of acid. Since we will be using phenolphthalein as an indicator, we will
use two clear sodas: Sprite and 7-Up. Sprite and 7-Up contain citric acid as well as carbonic acid, which is a product
of the dissolved carbon dioxide. We have allowed the soda to become “flat” so that it primarily contains citric acid.
We will measure the concentration of citric acid.
To determine the concentration of citric acid, we will perform a titration. We will find the unknown concentration of
acid by adding a known concentration of a base drop by drop until the equivalence point is reached. An indicator will
be used. When neutralization has occurred, the solution will change color. Because of the nature of the chemicals
used to test the soda for the acids, the liquids will become dangerous to your health. While it may be tempting, do
not drink any of the soda in the experiment.
Materials:
Sprite
7-Up
test tubes
test tube rack
graduated cylinder (10 mL)
.2M NaOH
pipettes (2)
phenolphthalein solution
goggles
apron
test tube holder
pH paper
Procedure:
1) Make a prediction as to which soda you and your group think will contain the highest concentration of acid
(please write in complete sentences):
2) Using a graduated cylinder, determine the number of drops from your pipette to make 1 mL. Record the
number of drops in 1 mL. Repeat to make sure your measurement is correct. You will need this info later.
1mL = _______drops
3) Bring one test tube to the front of the room and measure out 5 mL of one of the sodas. Return to your
group. Use the pH paper to determine the pH of the soda. Record the approximate pH in your data table.
Now add 2 drops of phenolphthalein to the test tube with soda.
4) Using a pipette add NaOH to the soda one drop at a time, shaking gently after each drop. Keep adding drops
until a light color appears and does not disappear after shaking. Record the number of drops of NaOH
required for neutralization in your data chart along with any other observations you observe as you do the
lab. Discard the contents down the drain. Rinse the test tube thoroughly with water.
5) Repeat steps 3 and 4 using the second soda.
6) When you’re finished, clean up and return the materials to where they came from.
Results:
Data Table 1: Lab Group Results
Type of
Soda
Color of pH
Paper
Approximate pH
(determined by pH
paper)
Drops of NaOH
(number)
mL of NaOH
Observations
Sprite
7-Up
Analysis:
1) What happened as you added drops of NaOH to the soda?
2) What color does phenolphthalein turn? What is happening at the point when the solution changes color?
3) Which soda appears to have the highest concentration of citric acid? Explain your answer?
4) After performing the calculations below, discuss the results and compare your findings to your original
prediction. (Make a conclusion beyond the obvious restatement of your numerical answers)
Calculations:
Balance the following equation (citric acid + sodium hydroxide = trisodium citrate + water
H3C6H5O7 +
NaOH 
Na3 C6H5O7 +
H2O
Sprite
1. Using your group’s data, calculate the number of moles of NaOH needed to neutralize the sprite. Remember that
the NaOH was a 0.2 M solution (0.2 moles/Liter)
2. Complete the sentence:
In the neutralization reaction of citric acid with NaOH, to neutralze 1 mole of H3C6H5O7 , _______ moles of NaOH
are necessary.
3. Use the information in problems 1 and 2, determine how many moles of H3C6H5O7 were neutralized.
4. Calculate the original molarity (moles/Liter) of the citric acid in the sprite solution.
7-UP
1. Using your group’s data, calculate the number of moles of NaOH needed to neutralize the 7-UP. Remember that
the NaOH was a 0.2 M solution (0.2 moles/Liter)
2. Complete the sentence:
In the neutralization reaction of citric acid with NaOH, to neutralze 1 mole of H3C6H5O7 , _______ moles of NaOH
are necessary.
3. Use the information in problems 1 and 2, determine how many moles of H3C6H5O7 were neutralized.
4. Calculate the original molarity (moles/Liter) of the citric acid in the 7-UP solution.