Separation of a Dye Mixture Using Chromatography

Product Details

The entire palette of artificial food colors is derived from just seven dyes certified by the FDA for use in food, drugs and cosmetics. How can these FD&C dyes be identified in a mixture? How do the molecular structures of the dye molecules influence their properties, relative solubility or affinity for different solvents? The purpose of this advanced-inquiry lab is to investigate the factors that influence the separation of food dyes using paper chromatography.

Students begin by comparing the separation or resolution of three FD&C dyes using two solvents. Then students design an experiment to identify a solvent that will give maximum resolution of a mixture of dyes.  This kit contains hazardous materials and is therefore not returnable due to DOT regulations.

Complete for 24 students working in pairs.

2024 CED Alignment:  

Unit 2 - Compound Structure and Properties  

Unit 3 - Properties of Substances and Mixtures  

Topic 2.2 - Intramolecular Force and Potential Energy  

Topic 3.1 - Intermolecular and Interparticle Forces 

Description of the Lab  

Students separate a mixture of dyes using chromatography and calculate Rf values to quantify retention. They explain their results by connecting polarity, solubility, and intermolecular forces. This lab develops a particle-level view of separation processes frequently seen in AP experimental questions. 

Learning Objectives 

• LO 2.2.A – Represent the relationship between potential energy and distance between atoms, based on factors that influence the interaction strength. 

• LO 3.2.A – Explain the relationship among the macroscopic properties of a substance, the particulate-level structure of the substance, and the interactions between the particles. 

Skills Students Will Learn 

• 2.C – Identify experimental procedures that are aligned to a scientific question (which may include a sketch of a lab setup). 
  In this lab: Students use chromatography to separate dyes based on polarity. 

• 4.C – Explain the connection between particulate-level and macroscopic properties of a substance using models and representations. 
  In this lab: Students relate IMF and polarity to dye movement and Rf values. 

• 6.F – Explain the connection between experimental results and chemical concepts, processes, or theories. 
  In this lab: Students explain separation results using molecular-level understanding of solubility and polarity.