Chromatography Colours – Separating Ink in the Classroom
Chromatography is one of the simplest but most powerful techniques in school science. With just filter paper, water, and a few pens, students can see how mixtures are separated into their component colours.
The Experiment
-
A line is drawn in pencil near the bottom of filter paper.
-
A small spot of ink is placed on the line.
-
The paper is dipped into a solvent such as water, making sure the ink spot is above the liquid.
-
As the solvent travels up the paper, it carries different dyes at different speeds, leaving a colourful pattern called a chromatogram.
The Science
Chromatography works because the dyes in the ink have different solubilities and are attracted differently to the paper.
-
Dyes that are more soluble move further up.
-
Dyes that stick more to the paper stay closer to the baseline.
The result is a separation of the mixture into individual colours.
Extensions
-
Students can calculate Rf values (distance moved by dye ÷ distance moved by solvent front).
-
Compare different brands of pen to see if they use the same dyes.
-
Link to real-world applications such as testing for food colourings, analysing drugs in forensic science, or checking purity in chemistry.
Why It Works in Teaching
Chromatography is quick, visual, and memorable. It teaches students about mixtures, solubility, and separation techniques while producing results they can see and measure. It’s one of those experiments where science feels like detective work.
No comments:
Post a Comment