How many different colors can you detect in total? Extra: Most watercolor marker inks are colored with synthetic color molecules. Artists often like to work with natural dyes. It is fairly easy to make your own dye from colorful plants such as blueberries, red beets or turmeric.
To make your own dye, have an adult help you finely chop the plant material and place it in a saucepan. And add just enough water to cover the plant material. Let the mixture simmer covered on the stove for approximately 10 to 15 minutes. If, at this point, the color of your liquid is too faint, you might want to remove the lid of the saucepan and continue boiling until some liquid has evaporated and a more concentrated color is obtained.
Let it cool and strain when needed. Now you have natural dye. Handle with caution, as it can stain surfaces and materials. To investigate the color components of this dye, repeat the previous procedure but replace the marker line with a drop of natural dye.
A dropper will help create a nice drop. Let the drop of dye dry before running the paper strip. Would the color of your natural dye be the result of a mixture of color molecules or one specific color molecule? Does the marker of the same color as your natural dye run in a similar way as your natural dye does? Extra: In this activity you used water-soluble markers in combination with water as a solvent. You can test permanent markers using isopropyl rubbing alcohol as a solvent.
Do you think similar combinations of color molecules are used to color similar-colored permanent markers? Extra: You can investigate other art supplies, including paints, pastels or inks in a similar way. Be sure to always choose a solvent that dissolves the material that is being tested to run the chromatography test. Isopropyl rubbing alcohol, vegetable oil and salt water are some examples of solvents used to perform paper chromatography tests for different substances.
Cleanup Throw away the paper strips and wash the glasses. Build a Cooler. Get smart. Sign up for our email newsletter. Sign Up. Support science journalism. You only need enough for the chromatography strip to soak up, so just a few ounces is plenty. Lower the chromatography strip into the water. Keeping your chromatography strip vertical, lower it into the water. Make sure that you have an apparatus set up to hold the strip there, as this process can take quite a bit of time.
The bottom of the strip should be submerged, but the marker line should not be submerged. If you accidentally submerge this line, throw the strip away and make another.
This way, the strip dangles down and just barely touches the water. Wait patiently. As the water moves up the strip, it will carry the different compounds in the marker with it. The lighter smaller compounds will move faster, and the heavier larger compounds will move slower. This is a slow process, however. Watch the strip until you see the water reach about 1 inch 2. Don't carry the system after submerging the strip; avoid any stirring that will affect the result by diffusion of bands.
Part 3. Take the strip out. Place it on a smooth surface and wait for it to dry. Count bands you see. Once you have removed the strip from the water, your bands should stay in place.
This will allow you to count how many different bands are visible on your strip. Notice the color of each band. These pigments all have their own unique colors. When you separate them into bands, the bands will be the color of that individual pigment. By noting the color of each band, you can analyze what color pigments went into creating the black ink in the marker. List the bands from the top of the strip to the bottom.
Write the colored bands down based on how far they traveled. The bands near the top are your lightest compounds, and the bands near the bottom are your heaviest compounds. You are also likely to notice a color trend from top to bottom.
Lighter colors are usually smaller compounds, and thus move farther up the strip, and darker colors will linger closer to the bottom because they are generally heavier compounds. You can calculate the Rf value for any band by dividing the distance the band traveled from the original line to the distance the solvent traveled from the original line.
Chromatography separates substances into their components. All forms of chromatography work on the same principle. They all have a stationary phase a solid, or a liquid supported on a solid and a mobile phase a liquid or a gas. Not Helpful 23 Helpful Why does chromatography work? What should happen if I attach a different substance, such as chlorine? It works on the principle of adsorption or distribution in between mobile and stationary phase.
Chlorine is a single substance we use to separate the mixture of the substances. Not Helpful 14 Helpful There is a slight difference. Chromatography is the process or technique; a chromatogram is the result of chromatography on paper.
Using a pencil and ruler to measure accurately, draw a straight line across the paper, about 1. This is the starting line. Draw another line about 10 cm above the bottom edge. On the starting line, measure in from one side about 2.
Draw seven more, 1. In the center of each X, make a small spot of ink color in this order: black, burgundy, red, pink, violet, turquoise, green, blue When you have finished, you should have something that looks like Figure 3.
Figure 3: Prepared Chromatography Paper Go back over each ink spot a second time to ensure there is enough ink in the spot. Obtain a small piece of tape and gently curl the paper into a cylinder, with the spots on the outside.
Tape the ends together near the top and bottom, taking care that the two edges of the paper do not touch. If they do touch, the eluent will creep on a diagonal, and the spots will run together, or not in straight lines. Obtain a piece of plastic wrap to cover the top. Gently place the paper cylinder into the beaker and cover the top with the plastic wrap. Remember that the spots must be above the liquid level for the experiment to work. Watch the eluent creep up the paper until it begins to move some of the ink.
It will take about minutes for the solvent front to reach the finish line. When the solvent front reaches the finish line, remove the paper from the beaker, being careful to touch only the top. Let excess eluent drip into the beaker. Gently remove the tape and lay the chromatogram on a piece of paper towel in the hood. Leave the paper in the fume hood, where it will dry completely. If needed, use a heat lamp in the fume hood to dry the chromatogram; if using the heat lamp, allow minutes to dry.
The reason for covering the container is to make sure that the atmosphere in the beaker is saturated with solvent vapour. Saturating the atmosphere in the beaker with vapour stops the solvent from evaporating as it rises up the paper. As the solvent slowly travels up the paper, the different components of the ink mixtures travel at different rates and the mixtures are separated into different coloured spots.
It is fairly easy to see from the final chromatogram that the pen that wrote the message contained the same dyes as pen 2. You can also see that pen 1 contains a mixture of two different blue dyes - one of which might be the same as the single dye in pen 3. Some compounds in a mixture travel almost as far as the solvent does; some stay much closer to the base line.
The distance travelled relative to the solvent is a constant for a particular compound as long as you keep everything else constant - the type of paper and the exact composition of the solvent, for example.
The distance travelled relative to the solvent is called the R f value. For each compound it can be worked out using the formula:. For example, if one component of a mixture travelled 9. In the example we looked at with the various pens, it wasn't necessary to measure R f values because you are making a direct comparison just by looking at the chromatogram.
You are making the assumption that if you have two spots in the final chromatogram which are the same colour and have travelled the same distance up the paper, they are most likely the same compound. It isn't necessarily true of course - you could have two similarly coloured compounds with very similar R f values.
We'll look at how you can get around that problem further down the page. In some cases, it may be possible to make the spots visible by reacting them with something which produces a coloured product. A good example of this is in chromatograms produced from amino acid mixtures.
Suppose you had a mixture of amino acids and wanted to find out which particular amino acids the mixture contained. For simplicity we'll assume that you know the mixture can only possibly contain five of the common amino acids. A small drop of a solution of the mixture is placed on the base line of the paper, and similar small spots of the known amino acids are placed alongside it.
The paper is then stood in a suitable solvent and left to develop as before. In the diagram, the mixture is M, and the known amino acids are labelled 1 to 5. The position of the solvent front is marked in pencil and the chromatogram is allowed to dry and is then sprayed with a solution of ninhydrin.
Ninhydrin reacts with amino acids to give coloured compounds, mainly brown or purple. The left-hand diagram shows the paper after the solvent front has almost reached the top. The spots are still invisible. The second diagram shows what it might look like after spraying with ninhydrin. There is no need to measure the R f values because you can easily compare the spots in the mixture with those of the known amino acids - both from their positions and their colours.
And what if the mixture contained amino acids other than the ones we have used for comparison? There would be spots in the mixture which didn't match those from the known amino acids. You would have to re-run the experiment using other amino acids for comparison.
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