stationary and a Suggest how process of the difference between mobile phase. Separation chromatographic chromatography. coloured substances. depends on the distribution methods can be used for Students should calculate of substances between the distinguishing pure Describe to another Rf values. phases. substances from impure student what the Rf is substances. and instructions on how to AT skills covered by this The ratio of the distance calculate the Rf value. practical activity: 1 and 4. moved by a compound Interpret chromatograms (centre of spot from origin) and determine Rf values Devise a method for to the distance moved by from chromatograms. distinguishing between the solvent can be pure and impure expressed as its Rf value: Provide answers to an substances using appropriate number of chromatography. significant figures. WS 2.4, 2.6 Different compounds have MS 1a, 1c, 1d, 2a different Rf values in different solvents, which can be used to help identify the compounds. The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents.
stationary and a mobile phase. Separation depends on the distribution of substances between the phases. The ratio of the distance moved by a compound (centre of spot from origin) to the distance moved by the solvent can be expressed as its Rf value: Different compounds have different Rf values in different solvents, which can be used to help identify the compounds. The compounds in a mixture may separate into different spots depending on the solvent but a pure compound will produce a single spot in all solvents. Suggest how chromatographic methods can be used for distinguishing pure substances from impure substances. Interpret chromatograms and determine Rf values from chromatograms. Provide answers to an appropriate number of significant figures. WS 2.4, 2.6 MS 1a, 1c, 1d, 2a process of chromatography. Describe to another student what the Rf is and instructions on how to calculate the Rf value. Devise a method for distinguishing between pure and impure substances using chromatography. the difference between coloured substances. Students should calculate Rf values. AT skills covered by this practical activity: 1 and 4.