Chromatography

Separating different pigment solutes from food coloring

How it works

Solvent (the water or other liquid) particles are attracted to the paper particles and the liquid moves up the paper

Dye particles are attracted to both paper particles and liquid particles.

The dye particles are pulled up by the liquid, but remain on the paper.

water

time

Cause of the separation

Blue particles end up on top because they traveled faster up the paper.

Both types of dye particles are attracted to water and paper.

So, is the speed of the movement due to greater attraction to the liquid or greater attraction to the paper?

Results of Additional Experiments

Paper towel, newsprint, and orange paper all reversed the color order. Yellow went farther than blue.

Alcohol, milk, and soda all had the same color order as the initial experiment. Blue went farther than yellow.

Origin of green

Hypotheses #1 and #2: Supported or Rejected?

#1 The blue particles are more attracted to water so they move faster. Rejected The different liquids did not change the color

order. #2 The yellow particles are more

attracted to paper so they move slower. Supported Changing the paper changed the color order.

How it works-continued

As the water particles move past the dye, the blue particles are moved more easily because they are less attracted to the paper.