In a paper chromatography experiment, a red dye spot is placed 1 cm from the baseline. The solvent front travels 10 cm. The red dye moves 6 cm. What is the Rf value? If the solvent front now travels 12 cm while the dye spot remains at 6 cm, what is the new Rf?
Answer
0.6; 0.5
The correct answer is 0.6; 0.5 — When the solvent front moves to 12 cm and the dye spot stays at 6 cm, recompute Rf: 6 cm ÷ 12 cm = 0.5.
Step-by-step solution
- Calculate Rf as dye distance divided by solvent distance: 6 cm ÷ 10 cm = 0.6.
- When the solvent front moves to 12 cm and the dye spot stays at 6 cm, recompute Rf: 6 cm ÷ 12 cm = 0.5.
Common mistake: Assuming Rf changes only if dye moves
Concept tested: Paper chromatography Rf calculation
Published · How this solution was prepared and checked
← All Separation of Substances questions