Lab Ch 3 Chromatography of Markers & Skittles

Transcription

1 Introduction Reproduce beautiful, multicolor art patterns using paper chromatography! Various color pigments that make up black inks and candy can be separated using chromatography. The inks are spotted onto a filter-paper circle containing a paper wick in the center, and the wick is placed into a cup of water. As water seeps outward through the paper, the different color pigments in the ink and candy mixtures separate out in a circular or radial pattern, producing a multicolor artistic effect. Objective The purpose of paper chromatography is to separate a mixture into its various components. Using a sample that is a mixture of several highly colored components, such as ink or candy dyes, allows the scientist to see the components as they separate. Materials for Marker Chromatography Chemical 2 Markers (water soluble) Black and green Tap water Equipment (2) 150mL or 250mL Beakers Pencil Filter Paper Scissors Lab Illustrations for Markers Part 1: Procedures for Markers 1. Obtain a piece of filter paper. Using a sharp pencil (NOT PEN), poke a small hole in the center of the filter paper.

2 2. With a black (water soluble) marker, place a small but concentrated spot of ink from marker about 1cm from the center hole onto the filter paper. The spot may be a dot, a wedge, a short-line, an arc, etc. See figure 1 above for example. 3. Grab a piece of cut pie-shaped filter paper. 4. Roll up a filter paper wedge into a tight cone and insert the cone-shaped wick into the hole in the center of the filter paper. 5. Set the prepared filter paper circle on top of the water-filled cup. 6. IMPORTANT. The wick needs to BARELY touch the water in the beaker. So you may have to dump or add water into the beaker. 7. The teacher will demonstrate this to you. See lab illustration above. 8. When the water has advanced to within 1-2 cm of the outer edge of the filter paper, carefully lift the chromatogram and set it on a paper towel to dry. 9. Repeat this process with a green marker using a new piece of filter paper. You can design a different pattern Spots/lines. 10. Observation/Data Table: (Leave about half a page space to put both your filter papers here) Data table Cut the filter papers in half so each partner has a half for their data. Staple filter papers to lab. (MAKE SURE THEY ARE DRY FIRST!!!) Black Marker Green Marker

3 Post-lab Questions 1. Why is it important that only the wick and not the filter paper circle be in contact with the water in the cup? 2. Do all the colors move the same distance? Is there one color that traveled further on the filter paper compared to other colors? 3. What real world application could this technique of chromatography have? You must name at least one application and explain how chromatography could be used. Part 2: Materials for Chromatography Chemicals Equipment DI water 2 Filter papers Scissors 0.1% Salt solution Beakers Petri dish Pipets Pencil

4 Lab Illustrations for Part 2: Procedures for Chromatography 1. Grab a petri dish (top and bottom). In the small petri dish put 2 different color (not red, yellow, or blue) in it on opposite sides. 2. Open the top of DI water bottle. Using a pipet grab some DI water and squeeze a little water onto each piece of candy to start dissolving the shell. 3. While you wait for the candy to dissolve, grab 2 filter papers and cut your filter papers into a rectangle. 4. Draw a pencil line about 2 cm from the bottom edge of the paper. Do not use pen, because the ink will run. This is your origin line. 5. When the water around the candy has turned color, using a separate pipet squeeze the colored water into the pipet. 6. Drop a few drops of colored water on the origin line on your filter paper. You may need to add several drops to ensure you have enough dye. 7. Repeat this with each color on separate filter paper rectangles, leaving about 2 cm between each color. 8. Let the filter paper dry completely. 9. Teacher has prepared a salt mixture of 0.1% (1g of salt to 1L of water). Mix until the salt has completely dissolved. 10. Pour a very small amount (about 20 drops) of the salt mixture into the bottom of a glass or jar. Just trying to cover bottom of beaker.

5 11. Place filter paper in the glass so that it is standing up and the bottom is barely touching the surface of the salt solution. 12. You can tape the top of the filter paper to a pencil and hang it down into the solution if you have a hard time getting it to stay right at the surface. 13. When the water has advanced to within 1-2 cm of the outer edge of the filter paper, carefully lift the chromatogram and set it on a paper towel to dry. 14. Observe the salt water rising up the paper by capillary action until it is almost at the top. 15. Let the paper dry completely. 16. Look back at the in the petri dishes. Notice water happens to the letters on the candy shell. S letters on are printed in edible white ink. The ink won't dissolve in water. When the candy shell dissolves, the letters peel off and float to the top. Pretty Cool!! Data table Cut the filter papers in half so each partner has a half for their data. Staple filter papers to lab. (MAKE SURE THEY ARE DRY FIRST!!!) Color Skittle: Color Skittle: Post-lab Questions 1. Why do you think some color dyes move further up the paper than others?

6 Part 3: Color Mix 1. Fill the bigger petri dish with enough water just to cover the bottom. 2. Drop a Skittle of different color along each side so that they are across from each other and evenly spaced. 3. Wait and observe. Data table Draw & Color the Before and After Color mix. Before Colors Mix After Colors Mix Post-lab Questions 1. What did you notice about the color mixing of the? Did they mix evenly or did one color dominant over the others? 2. What type of mixture is the color dyes from the : Homogeneous or Hetergeneous (Color you choice) 3. If you had time to experiment with other candies, can you name 2 candies that have dyes in them?

7 4. We discussed temperature has an effect on Matter. If you tested the candies with different temperatures of water, what would happen to the dissolving rate in cold water vs hot? Disposal/Clean Up, solids and filter paper go in the trash Clean ALL equipment with LAB Equipment soap & brushes Leave dishes to dry inverted on a paper towel. Clean Lab BENCH with small soap bottle and sponge. Wash hands with hand soap. Let me know when you are ready. Do not get unprotected until dismissed.