Separation of a Synthetic Pain Relief Mixture

Product Details

Most over-the-counter (OTC) drugs are mixtures of active drug ingredient(s) and binders with a variable composition. Investigate the physical properties of ingredients in a synthetic pain relief mixture and determine its percent composition.

In the introductory activity, students test the solubility of each possible OTC component in ethyl acetate and in an aqueous solution of sodium bicarbonate. Using these results, students design of a flow chart procedure to separate the components and determine the amount of each. Optional extension activities include varying the composition of the OTC mixtures and analyzing consumer samples. Students may also measure the melting points of the isolated components to confirm their identity.

This advanced inquiry lab integrates student understanding of solubility and acid–base chemical reactions. 

Complete for 24 students working in pairs. Perform this experiment in a fume hood or well-ventilated lab.

2024 CED Alignment:  

Unit 3 - Properties of Substances and Mixtures  

Topic 3.9 - Separations of Solutions and Mixtures 

Description of the Lab  

Students separate and identify the components of a commercial pain relief tablet using solubility and acid-base reactions. The lab emphasizes polarity, intermolecular forces, and practical separation techniques—mirroring the kinds of experimental separation questions seen on the AP Exam. 

Learning Objective 

• LO 3.9.A – Explain the results of a separation experiment based on intermolecular interactions. 

Skills Students Will Learn 

• 2.E – Identify or describe potential sources of experimental error. 
  In this lab: Students consider errors in mass recovery and solubility assumptions. 

• 4.C – Explain the connection between particulate-level and macroscopic properties of a substance using models and representations. 
  In this lab: Students relate solubility and IMF to how each compound dissolves in solution. 

• 6.D – Provide reasoning to justify a claim using chemical principles or laws, or using mathematical justification. 
  In this lab: Students justify the identity of each mixture component using evidence from solubility