An environmental laboratory uses paper chromatography to test a coloured contaminant in river water. The distance moved by the spot is measured correctly. However, the analyst uses the distance from the origin line to the top edge of the paper as the solvent distance. The solvent front stopped below the top edge.
What effect does this have on the Rf R_f\,Rf value the analyst calculates?
It cannot be calculated, because the solvent did not reach the top edge
It must be equal to 1, because the full paper distance was used
It is too high, because the denominator in the calculation is too large
It is too low, because the denominator in the calculation is too large
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.