A student carries out paper chromatography to analyse the dyes in a black permanent marker, using water as the mobile phase. One of the dye spots remains on the baseline and does not move up the paper.
Give one change that could be made to the experiment to obtain an Rf R_f\,Rf value for this dye.
107 exam-style questions on Edexcel GCSE Chemistry 3.2 Methods of separating and purifying substances, covering 3.2.1 Pure substances and mixtures, 3.2.2 Techniques for separating mixtures, 3.2.3 Paper chromatography and Rf values, and 3.2.4 Making water potable. Each one has a worked solution and a mark scheme showing where the marks go.