In the Classroom

Science Discipline(s) Chemistry   Topics Chromatography   Activity Title Tie Dye Spin Chromatography   Materials
  • 1 gallon Water
  • 36 – Water-soluble markers (Non-Toxic)
  • 40- Filter paper (or coffee filters), cut into strips that are at least 3 inches in diameter
  • 40 -Clear, plastic cups
  • 40 – Pencils
  • 3 – Rolls Tape
  Procedure
  • Have participants draw a relatively thick line on the coffee filter about an inch above the water’s edge in one color, using the water-soluble magic markers. The line should be about a centimeter thick. The line should stretch from one end of the filter to the other.
  • Participants tape the other end of the filter to a pencil.  Tape it tightly so that when the chromatography is complete and the coffee filter is soaked, the paper won’t tear off the pencil.
  • Fill the cup with about half an inch of water.
  • Place the coffee filter inside the cup, with the pen or pencil resting atop the cup. The end of the coffee filter should be resting in the water at this point. If it is not, or if the mark on the filter is submerged, remove the coffee filter, and fix the problem. Add more water if the filter was not touching the water, and, if the mark was submerged, throw away that coffee filter, and try again, this time placing the mark higher on the paper.
  • Remove the coffee filter from the cup when you think the colors have completely strained out. There should be different colors moving in a long strip from the bottom of the filter up to the top.
  Questions
  • PK – grade 3 students
    • What happens to the colors when the water reaches the colored line?
    • What other colors do you see besides the main color you used to draw the line?
  • Grade 4 – 6 students
    • What happens to the colors when the water reaches the colored line?
    • What other colors do you see besides the main color you used to draw the line?
    • Why do you think some colors are further away from the line you drew?
  • Middle school students
    • Why do you think some colors are further away from the line you drew?
    • What are the different phases that make the reaction happen?
    • What are the different states of matter in this experiment?
  • College-level/ scientific description
    • What are the different phases that make the reaction happen?
    • What are the different states of matter in this experiment?
    • What causes the differentiation between the distance in colors away from the original line
  Explanation The word chromatography is derived from the Greek words chroma and graph, which means “color writing.” Chromatography is the separation of molecules within a mixture or compound.  This technique was developed in 1901 by the Russian Botanist, Mikhail Tsvet, in order to separate the different pigments present in plant dyes.  Chromatography, such as Thin Layer Chromatography (TLC) and Column Chromatography, is a valuable technique used in many labs today to separate compounds and molecules. The movement of molecules and compounds along a solid surface is caused by capillary action.  Capillary action is the movement of liquid molecules across a solid surface due to greater attraction to the surface as opposed to the other molecules present.  In today’s activity the dyes from markers will be used to separate the different pigments that make them up.  The different pigmentations present in the markers will vary in mobility speeds based on the polarity of these pigments.  Polarity is the variations of electronegativity present within a molecule that is determined by the different elements that make it up.  The more polar pigments will react with the surface more readily than nonpolar molecules, which will slow down their mobility and overall distance traveled.  The different colors on the filter paper are made up of reflected and absorbed light.  The color that we see is the color that is reflected and the absorbed light is the complementary color of the light reflected.  Overall, students will learn about the separation of molecules and compounds through chromatography using water soluble markers and filter paper.
  • PK – grade 3 students
    • Chromatography is a way to separate a mixture of chemicals.  We can see what colors are mixed together to make other colors during this experiment. The water moves up the filter paper and separates the colors when it reaches the ink. The colors in markers result from food dyes. Some markers might contain only one dye while others might be a mixture.
  • Grade 4 – 6 students
    • Chromatography is a way to separate a mixture of chemicals.  We can see what colors are mixed together to make other colors during this experiment. The water moves up the filter paper and separates the colors when it reaches the ink. Some colors are closer/further away from the line that was drawn because some chemicals move faster than others, like runners in a race. The chemicals in a liquid mixture travel at different speeds over a stationary solid.  Some of the markers will contain only one kind of food dye and others will contain several dyes and are a mixture. The dyes are molecules that are made up of different elements from the periodic table.
  • Middle school students
    • Chromatography is a way to separate a mixture of chemicals. Chromatography works when there is one state of matter (liquid – dye) moving over the surface of another state of matter (solid- filter paper). In this experiment, the dye is called the mobile phase, and the filter paper is called the stationary phase. Chromatography is a surface effect so chemicals in the dye or liquid mixture spread out because they move at different speeds over the stationary solid filter paper. Mixtures of more than one dye can be separated into the individual dyes using chromatography.
  • College-level/ scientific description
    • Chromatography is a way to separate a mixture of chemicals. Chromatography works when there is one state of matter (liquid – dye) moving over the surface of another state of matter (solid- filter paper). In this experiment, the dye is called the mobile phase, and the filter paper is called the stationary phase. Chromatography is a surface effect. Chemicals in the dye or liquid mixture spread out because they move at different speeds over the stationary solid filter paper. These speeds are caused by a process called adsorption. Adsorption is an exchange of molecules between the surface of the solid and liquid that gives an adhesive effect. Every chemical undergoes adsorption in different ways, spending more or less times in either the solid or liquid phase.