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Introduction Your instructor has prepared an extract of chloroplast pigments from fresh green grass or fresh spinach. A blender was used to rupture the cells, and the pigments were then extracted with acetone, an organic solvent. Work- ing with one other student, begin this exercise by separating the pigments extracted using paper chromatography. To do this, you will apply the pig- ment extract to a cylinder of chromatographic paper. You will then place the ylinder in a jar with the organic solvents petroleum ether and acetone. The solvents will move up the paper and carry the pigments along: the pigments will move at different rates, depending on their different solubilities in the solvents used and the degree of attraction to the paper. The leading edge of the solvent is called the front. Discrete pigment bands will be formed from the front back to the point where pigments were added to the paper. The following information will be helpful to you as you make predictions and interpret results: 1. Polar molecules or substances dissolve (or are attracted to) polar molecules 2. Nonpolar molecules are attracted to nonpolar molecules to varying degrees 3. Chromatography paper (cellulose) is a polar (charged) substance. 4. The solvent, made of petroleum ether and acetone, is relatively nonpolar. 5. The most nonpolar substance will dissolve in the nonpolar solvent first. 6. The most polar substance will be attracted to the polar chromatography paper; therefore, it will move last.CH CH CH н сн CH CH2 CH, HS ,с CH2CH Mg Mg CH H,C CH H3C CH2 COOCH3 CH2 COOCH3 a. Chlorophyll a b. Chlorophyll b H.cCH CH CH CH CH H.C CH CH .Beta carotene H.C CH СН CH CH CH -cH = CH-C=CH-, CHECH _ C = CH-CH=CH-CH=C-CH=CH-CH=C-CH=CH- но CH он d. XanthophyllFIGURE 6.4 Molecular structure of major leaf pigments. The molecular structure of chlorophyll (a), chlorophyll (b), carotene (c), and xanthophyll (d). To determine polarity, count the number of polar oxygens present in each molecule. Use this information and the molecular structure of major leaf pigments to predict the relative solubilities and separation patterns for the pigments and to identify the pigment bands. Study the molecular structure of the four common plant pigments in Figure 6.4. As you study these diagrams, rank the pigments according to polarity in the space provided. To determine polarity, count the number of polar oxygens present in each molecule. Most polar Least polar: Hypothesis State a hypothesis relating polarities and solubilities of pigments.Prediction Predict the results of the experiment based on your hypothesis (if/then)Pre lab

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