Acidity of Beverages

Product Details

How much acid is in fruit juice? Fruit juices get their sweet taste from sugars and their sour or tart taste from weak acids, such as citric acid. If the juice contains too much sugar, it will taste bland, but too much acid and the juice will taste sour. The concentration of acids in various consumer beverages may be determined by titration with sodium hydroxide.

Students begin with an introductory activity for determining the proper indicator to use in the titration of acetic acid, a characteristic weak acid. The results provide a model for guided-inquiry design of a procedure to obtain titration curve data and calculate the molar concentration of acid in a beverage. Experiments may be performed as a cooperative class study or as open-inquiry activities. Three juice samples are provided, but students may also use any other light-colored soft drink or beverage.

A wonderful real-world example of everyday chemistry that fulfills key learning objectives, such as designing experiments, interpreting data and using stoichiometric calculations, to predict reaction results!

Complete for 24 students working in pairs.

2024 CED Alignment:  

Unit 4 - Chemical Reactions  

Topic 4.6 - Introduction to Titration 

Description of the Lab  

Students titrate common beverages to determine the concentration of weak acids and construct titration curves to identify pKa and equivalence points. The lab emphasizes experimental precision and graph interpretation while reinforcing concepts in stoichiometry, solution chemistry, and acid-base reactions. 

Learning Objectives 

• LO 4.2.A Represent changes in matter with a balanced chemical or net ionic equation: i. For physical changes. ii. For given information about the identity of the reactants and/or product. iii. For ions in a given chemical reaction. 

• LO 4.6.A – Identify the equivalence point in a titration based on the amounts of the titrant and analyte, assuming the titration goes to completion. 

 Skills Students Will Learn 

• 4.B – Explain whether a model is consistent with chemical theories. 
  In this lab: Students interpret titration curves using acid-base theory to explain equivalence points and buffering regions. 

• 5.C – Explain the relationship between variables within an equation when one variable changes. 
  In this lab: Students analyze how volume of titrant added affects pH in the titration curve. 

• 6.D – Provide reasoning to justify a claim using chemical principles or laws, or using mathematical justification. 
  In this lab: Students calculate molarity and explain their results using titration stoichiometry and pH trends.