Marker Chromatography

Essential Question
How do different chemicals and molecules interact with each other?

Objectives

 * Explain why different chemicals move at different rates up the coffee strip.
 * Predict what will occur with different markers.
 * Identify what primary colors make up other colors.

Introduction & Student Background
What are the three primary colors and what are some of the colors you can make from that? How do different molecules interact with each other?

In this activity, students will learn how colors separate and combine to form different colors. They will put dots of washable marker onto coffee filter strips, and then soak them in water and wait as the colors separate from one another.

Vocabulary
chromatography - the separation of mixtures.

molecule - an electrically neutral group of two or more atoms held together by chemical bonds.

intermolecular forces - bonds that form between different molecules based on orientation and polarity. They are not as strong as intramolecular forces. 

polarity - when the electrons in a multiple-atom molecule are not evenly shared and therefore cause a slight positive and negative charge in different regions of the molecule. This causes stronger intermolecular forces with other polar molecules.

Materials

 * Washable markers of different colors
 * Coffee filter paper
 * Scissors
 * Tape
 * Glass of water
 * Straw or chopstick

PREP

 * 1) Cut the coffee filter into 1 inch strips.
 * 2) Lay out the markers.
 * 3) Fill the glass cups with an inch of water.

ACTIVITY

 * 1) Have students choose a color marker and put a dot at the bottom (about half an inch from the bottom) of the coffee filter strip.
 * 2) Tape the coffee filter strip to the center of the chopstick/straw.
 * 3) Hang the straw over the glass of water so that the marker dot is right above the water.
 * 4) Let the setup sit for 10 minutes.
 * 5) Return and remove the the coffee filter from the straw. What colors have shown up on the filter? Which color is highest/further up? Which one is the lowest?

How it Fits to Standard

 * Substances have unique properties based on their atomic structure.
 * The properties of an object depend on its shape and the material it is made from.
 * Carry out investigations by using instruments, observing, recording, and drawing evidence-based conclusions.

Follow Up
Each color that the marker consists of is made of a different chemical. Each chemical has its own polarity and some are more attracted to water molecules than other. The water moves up the coffee filter the quickest, and if the chemical is very attracted to water (intermolecular bonds) then it will move up further than a chemical that is not as attracted to water.