Which photosynthetic pigment is most soluble

The primary pigments in green plants are chlorophylls, represented by chlorophyll a and b, which appear green. Visible light, or white light, is made up of the colors of the rainbow. Some of these colors are absorbed "used" by pigments and others are reflected. Pigments appear the color of the reflected light, so the chlorophyll pigments do not use the green portion of the spectrum. The other two pigments are types of carotenoids, which appear yellow, orange, or brown.

The top band of pigments in the separation are carotenoids called carotenes, most likely beta-carotene, and appear yellowish-orange. The second type of carotenoid separated in the experiment are xanthophylls, which appear bright yellowish and are most likely lutein. The "loading line" is the location of the original pigment line painted on the paper.

A second experiment using the chloroplast pigment extract obtained using the methods described above can be easily done. Green-colored pigment extract is added into a test tube. Other pigments, such as carotenoids, are also present in chloroplasts and serve as accessory pigments, trapping solar energy and passing it to chlorophyll.

This makes chlorophyll b slightly more polar than chlorophyll a. Rf value can be used to identify compounds due to their uniqueness to each compound. Apparatus and chemical required.

The least soluble pigment traveled the shortest distance, and that was the chlorophyll b. The chlorophyll a molecule was in the middle of the other two and showed an intermediate solubility.

The purple and orange colors are more soluble in water, because of the rate in which they traveled as the filter soaked up the water. While watching food coloring move through water is simple, separating food coloring from water requires more effort.

Allow the water to evaporate away and you will be left with the food coloring remaining in the pan. What two components are found in the green dye? They will need to know that, of the functional groups present in the pigments in figure 1, alcohol groups are the most polar, ester and ether groups the least polar, and aldehyde and ketone groups are in between.

From this, we can deduce that carotenes are the least polar pigments no polar groups , and xanthophylls are the most polar two alcohol groups, one at each end of the molecule. Therefore, pigments 1 and 2 are likely to be carotenes, and pigment 4 is likely to be a xanthophyll. Pigment 3 is likely to be chlorophyll, since it is more polar than carotenes but less polar than xanthophylls. You can observe the characteristic green colour from chlorophyll on the chromatogram.

Now look at the Rf values, which range between 0 and 1, with 0 being a pigment that does not move at all, and 1 indicating a pigment that moves the same distance as the solvent. The Rf value varies depending on the solvent used, but the general order of the pigments from the highest to the lowest Rf value usually remains the same, because the nonpolar compounds move further than the polar compounds.

Rf values for various pigments using hexane, acetone and trichloromethane for the solvent are shown in table 1. After the experiment, you can ask your students some of the following questions to gauge their understanding of plant pigments and thin-layer chromatography.

Download this article as a PDF. His work focuses on the metabolic reprogramming of cancer metastasis. Together, they presented this activity at the Hands-on Science conference in Barcelona, and they frequently organise and participate in educational activities to help bridge the gap between university and secondary school students.

Combining the outdoor element of nature with the identification of different chemical structures produces a perfect applied science lesson. The analysis of the different pigments in leaves has a clear visual outcome that can then be related to the chemical structures of the different photosynthetic pigments.

This practical activity affords students the opportunity to move beyond basic paper chromatography to the more complex technique of thin-layer chromatography. This cross-curricular task will engage students who enjoy biology-based topics such as photosynthesis as well as students who enjoy the problem-solving aspect of analytical techniques in chemistry.

The activity is most suitable for students aged 14—16 as part of a science club or extension activity. In addition to the main method, the authors provide suggestions for using different solvents to enable students to carry out the experiment entirely independently. With further detail, the activity could also be useful for students aged 16— Many new terms are introduced, so the article provides an excellent chance to challenge students to understand concepts such as mobile and stationary phases, polarity of molecules and how biology is fundamentally based on chemical building blocks.

Colour, chlorophyll and chromatography Teach article.