Paper chromatography · 3 parts · syllabus 12.3

What is hiding in the green dye?

Draw the start line, spot a green dye beside two known dyes and decide how deep the water goes. Predict, lift the paper when you choose, mark the front, then read the ruler and work out Rf. Finally, find the substances in a sample that looks colourless.

Start learning Explore the experiment

Small sample spots remain above solvent as the covered paper chromatogram develops.

Follow the idea

Can one colour hide several substances?
Prepare and develop the mystery dye
Not started
What can the pattern tell you?
Compare spots and question purity
Not started
Measure travel, then reveal what you cannot see
Measure Rf and locate colourless substances
Not started

Unknown U separates into two spots beside known dyes A and B.

The experiment · A green dye, then a colourless sample · measure Rf yourself

Run it yourself, or project it for the class

Use the apparatus step by step and look closely at what happens. The whole experiment fits one screen, so it works on a projector too.

Open the experiment

Final check

Explain it on your own across all three parts. Hints and keys stay closed until you submit.

Take the final check

Return and recall

Come back after one to two weeks and answer with the lesson closed.

Recall questions

For teachers

Printable worksheets with their answer keys, the final check and the return questions for this module.

Open the teacher pack

Your saved work

Answers and earlier attempts stay in this browser. Export a copy to keep, to move to another device or to hand to your teacher. Importing a copy keeps your current answers and adds earlier attempts.

Import saved work

Scope and sources

Cambridge IGCSE Chemistry 0620 · 2026–2028 v2 · Original learning materials.

0620 Extended12.3.1–4: suitable solvent, coloured and colourless paper chromatography, known/unknown comparison, purity evidence and Rf. Bounded12.4.2 method choice. Illustrative data; no real practical or chemical identity certification.

Apparatus, amounts and times in the experiment are illustrative. Real practical work follows a teacher-approved safety method.

Official Cambridge syllabus

What is hiding in the green dye?

Follow the idea

Can one colour hide several substances?

What can the pattern tell you?

Measure travel, then reveal what you cannot see

Run it yourself, or project it for the class