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Separating Molecules

Experiment #5 from Vernier Chemistry Investigations for Use with AP* Chemistry

Education Level
High School


In this investigation, you will be given an aqueous mixture of two or more substances, all of which are FD&C food dyes. Your objectives will be to identify and separate the food dyes in the mixture, using two laboratory techniques.


The first objective is to try to identify the food dyes in the mixture, using absorbance spectroscopy. The absorbance spectrum of a solution of each food dye is a unique property of the substance. By carefully examining the absorbance spectra, you should be able to identify one or more of the food dyes.

The second objective is to separate the food dyes using chromatography. Chromatography is a name for a family of methods used to separate mixtures into their individual components. The method is based on the affinity that molecules have for other molecules, also known as intermolecular forces of attraction. You will use paper chromatography to separate the food dyes in your mixture.

Sensors and Equipment

This experiment features the following sensors and equipment. Additional equipment may be required.

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This experiment is #5 of Vernier Chemistry Investigations for Use with AP* Chemistry. The experiment in the book includes student instructions as well as instructor information for set up, helpful hints, and sample graphs and data.

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