A researcher extracted a coloured compound, U, from a flower. Compound U is known to be either pure compound A or pure compound B.
For each solvent, A, B and U were run together on one sheet of the same type of chromatography paper.
| Solvent | Distance moved by solvent front / mm | Distance moved by A / mm | Distance moved by B / mm | Distance moved by U / mm |
|---|---|---|---|---|
| 1 | 80 | 32 | 32 | 32 |
| 2 | 75 | 18 | 51 | 51 |
Calculate the Rf R_f\,Rf value of compound U in each solvent.
Use the results to identify compound U.
Explain why the result with solvent 1 was not enough to identify U.
113 exam-style questions on AQA GCSE Chemistry 8.1 Purity, formulations and chromatography, covering 8.1.1 Pure substances, 8.1.2 Formulations, and 8.1.3 Chromatography. Each one has a worked solution and a mark scheme showing where the marks go.