University of Virginia
Physics Department

Soda Science

A Physical Science Activity

Student Activity



  1. Measure 20 mL of colorless, carbonated beverages into test tubes or flasks. Set flask on sheet of white paper.
  2. Add 2 drops of 1% phenolphthalein indicator to each of the beverage samples. Swirl to mix.
  3. Add the NaOH solution drop by drop, until a permanent faint pink color indicates that the acid is neutralized. Carefully swirl the test tube after each drop is added.
  4. Record in the data table the number of drops of NaOH used.
  5. Repeat steps 3 and 4 with the second sample.

Data Sheet

Sample Kind of Soda # of drops of NaOH

  1. Did your samples require different amounts of NaOH for neutralization?

  2. Which sample is more acidic?

  3. Phenolphthalein changes from colorless to pink at a pH of 8. Explain why the indicator was colorless in the soft drink and became pink as the base was added.