Name ________________________12345_______________________ Date ____23.8.2013___________ Block _______
Training Lab: Paper Chromatography
I. Background Information: When working in a lab, scientists often need to identify different molecules that are present in a sample they are studying. There are many ways to identify unknown molecules/chemicals in a sample. The method you will be using today is called Paper Chromatography and consists of 2 steps. First, you will separate the unknown chemicals and then you will identify them. This process can also be applied to the food we eat everyday. When you eat food or drink liquids you are trying to get important chemicals to your cells. (chemicals that your cells might use for energy or maybe to build more cells.) Look at the food label below, though, and you’ll see a list of several chemicals that your cells cannot use. These chemicals may be added to keep the food from spoiling, give the food a flavor or texture that makes it taste better, or add color to the food/drink to make it look more appetizing so you will buy it. Many of the foods and drinks you buy each day would be clear or white without the addition of food dyes (artificial colorings).
Knowing this, we can ask what food dyes are used to make Kool-Aid, for example, look appetizing? Without food dyes, ALL flavors would be clear. In order to identify the food dyes in Kool-Aid, you must first separate them, and you will do this using paper chromatography. II. Materials: • 2 chromatography tubes • 2 strips of chromatography paper • Lemon-lime Kool-Aid solution • 1 pencil • 2 toothpicks • Grape Kool-Aid solution • Solvent (alcohol, salt, & water) • ruler
III. Procedure: DAY I: Separation of Chemicals 1. Obtain all the supplies you need (at supply table). 2. Cut 2 strips of chromatography paper so that each is about an inch longer than the tubes. 3. Cut one end of each paper strip to form a point (see drawing 1). 4. Draw a straight line across each strip...
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