Question

Pre-Lab Questions Rt for A 4.8 = 0.86 1. Figure 1 is a sample paper chromatogram for three samples: A, B and C. Label the drawing with the fol lowing items: the stationary phase, the mobile phase and the solvent front. R 5.6 2. Calculate the R, value for the spot in sample B using sample A as an example 3. Sample C gave two spots on the paper chromatogram What does this tell you about the composition of the sample? A В С 4. Based on the R, values of samples A and B, what can you conclude about the intermolecular attractions both samples have for the eluent and the paper? Figure 1 4.8 cm 5.6 cm 2.8 cm

Answer 1

Ilid Scient k tank paped supposit E Solvent front 48 cm ussens 2.80m2 paper Staticnaig phase]" 1 (spotting line) Onigin solvent Móbile phase) paper Chromatography consists of two phases : one mobile phase and one contigous Stationary phase. The stationay phase is a paper and the mole phase i u a solvent. The compounds in the mixture moves along with the mobile phase through Stationary phase and separates depending on the different degree of adhesion on paper of each component in the sample. 1. The sample needs to be sepa- eated is placed as a small deop on line on to the paper using capillary tube. The paper is then placed into a sealed contained with a Swallow lagen of Suitable solvent : The solvent level must be lower than the pan spotting line. The containee need to be covered to stop the solvent to evapo late!

Rr 2 Distance feavelled by the campound Distance travelled by the solvent. R6 for A=4.8 20.86 5.6 Rf for B; Rp = 2-0.5 5.6 3 The sample a contains both A and B in it. It is the mixtue of both compounds That is why a spots on the same position as for A and B is visible. The sample C contains both A and B 4) The components travel caith the solvent depends upon there things : The polarity of the sample indecule. The non polar components teavel faster than the polar component • The attraction between the sample melecule and the solvent oi solvent mixtun · The attraction between the sample and - the silica •

The Rr value of A is quater than B. This Indicates that A is more non polar and B is polas A travels faster because the force of attraction between VA and solvent is highed so it moves with Sdvent lastly · Buto attraction betazoa A and paper is less B teavel's less, the RC value is of affraction between B and and with B and paper why it is less moved with thus bind with paper. less, the force solvent is less § guates. That's solvent and neote as eluent in the solvent is chromatographic also called fermes.