Chromatography Experiment

A while back my dad, who is a Chemistry Professor told me about this experiment we could do called Chromatography.  I have not done any chemistry experiments with the girls and this sounded pretty cool so I knew I wanted to do it with the kids.

Basically Chromatography is the technique of separating the components of a mixture by absorption.  I know it sounds all complicated, but this experiment makes it really simple.  This is also a great experiment for kids who are learning about colors or color mixing.  Unlike our Water Transfer Experiment which mixed different colors to make a new color, This experiment will break up the colors so you can see what made the color you are working with.

Both my girls had fun with this, before we started the experiment I asked them what they thought the color black was made of.  They were not sure, so I asked if they thought it was made of all colors or no colors.  My oldest said all colors, my little one just answered what her sister did.

After we put the marked coffee filter into the water they were excited to see what happened, but we had to wait for the water to climb the filter.  I would recommend drawing your line more in the middle of the filter so there is less waiting time.  However the kids enjoyed watching all the colors bleed out once the water reached the line.  My little one thought it was the coolest thing! So we had to do it again!

What is happening with this experiment? When the water reaches the black line drawn on your filter the water will then separate the different colors in the ink.  This process is called Chromatography, which is the technique of separating different components of a mixture by absorption.  Feel free to try it with different colors, like a purple marker and see the red and blue separate, or Orange and see the yellow and red separate. 

Note: do not use a permanent marker.  Some markers may not work, we used a Cra-Z-Art washable marker.  We tried it with a Crayola marker and it did not work.  Some markers use a pure black ink and they will not separate, so your best bet is to buy a cheap one, they tend to work better for this.

Supplies
Coffee Filter
Black Marker (See Note Above)
Small Glass of Water
Scissors

Directions

 Fold your coffee filter in half and the cut it in half

 Cut the half of the filter in half so you have 4 pieces of filter

 Draw a line with your black marker on the filter

 Place the filter in the water and watch what happens when the water climbs to the marker line

 The water will separate the colors in the black marker

 See how many different colors you can find

 Do more colors appear the longer the filter is in the water?

 If you want try it again!  Just mark your filter and put it in water

 Waiting till the water reaches the line can be hard.