Chemistry project

roll no. :

Certificate

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This is to certify that XYZ of class XII-A, XXX School, Pitampura has persuaded his work and prepared the present dissertation entitled :-

“To determine the Rf value of dyes used in candies”

Under my guidance and supervision and to my total satisfaction.

Mrs. ABC

Apeejay School

Pitampura

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Acknowledgement

I acknowledge my indebtedness to Mrs. ABC, our chemistry teacher, for the painstaking effort she has taken in order to encourage me to do this project . I am very thankful to her for her valuable guidance, advice, kind cooperation and supervision for enabling me to do this project. Without her this project would not have been successful.

I am also grateful to Mr. Nath, our lab attendant, who provided us with the necessary equipments at the correct timing.

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aimTo determine the Rf value of dyes used in candies”

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ContentsS.No

Topic Page No

1 Introduction 62 Apparatus 73 Theory 84 Procedure 95 Observation 116 Result 147 Precaution 158 Bibliography 16

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IntroductionChromatography is the collective term for a set of laboratory techniques for the separation of mixtures. The mixture is dissolved in a fluid called the mobile phase, which carries it through a structure holding another material called the stationary phase. The various constituents of the mixture travel at different speeds, causing them to separate. The separation is based on differential partitioning between the mobile and stationary phases. Subtle differences in a compound's partition coefficient result in differential retention on the stationary phase and thus changing the separation.

Chromatography may be preparative or analytical. The purpose of preparative

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chromatography is to separate the components of a mixture for more advanced use (and is thus a form of purification). Analytical chromatography is done normally with smaller amounts of material and is for measuring the relative proportions of analysts in a mixture. The two are not mutually exclusive.

Apparatus Candy with a colored coating, like Gems At least 30 strips of paper

o All strips must be exactly the same size.

o 3 cm × 9 cm is a good size, but you can change this to fit your needs.

Wide-mouth jar Pencil

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Ruler Tape Salt Water Toothpicks Food coloring (red, green, and blue)

TheoryChromatography is a technique used to separate the various components in a complex mixture or solution. It works because the components of the mixture will differ in how much they "stick" to things: to each other, and to other substances.

Other material than paper and water can be used for chromatography, but in each chromatography apparatus there is generally a stationary phase and a mobile phase. In paper

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chromatography, the paper is the stationary phase, and water is the mobile phase.

Chromatography can be used to separate (purify) specific components from a complex mixture, based on molecular size or other chemical properties. It can also be used to identify chemicals.

With colored mixtures in paper chromatography, you can see the components separate out on the paper.

To calculate the Rf value, we use the equation:

Rf =

distance traveled by the sample component 

distance traveled by the solvent

Procedure1. Do your background research so that you are knowledgeable about the

terms, concepts, and questions, above.2. Use a pencil to lightly label which candy color or food coloring will be

spotted on each paper strip. Tip: do not use a pen for writing on the strips: the ink will run when the solvent passes through the strips.

3. Draw a pencil line 2 cm from the edge of each strip of paper.4. This will be the origin line.5. You will spot the candy color for each strip right on this line, as shown

below.

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6. Next you need to extract some dye from each candy you wish to test.7. Set the candy down on a clean plate in a single drop of water. Note: If

you use too much water, the dye will not be concentrated enough to see on the chromatography paper.

8. Leave it for a minute to allow the dye to dissolve.9. Remove the candy, then dip a clean toothpick into the now-colored

drop of water.10. Spot the candy dye solution onto the chromatography paper by

touching the toothpick to the chromatography strip, right in the center of the origin line.

11. Allow the spot to dry, then repeat the spotting at least three more times. You want to make sure to have enough dye on the chromatography paper so that you can see the dye components when they separate out on the paper.

12. Make five separate strips for each candy you want to test.13. Repeat step 4 for each color of candy you want to test (at least

three different colors).14. You also need to prepare chromatography strips with food

coloring dyes.15. These will be your known compounds, with which you will

compare the "unknown" candy dyes.16. For each food coloring color, use the same procedure as in step

4. You'll use a drop of food coloring as the source for dipping your clean toothpick.

17. Prepare a 0.1% salt solution for the chromatography solvent.18. Add 1/8 teaspoon of salt to 3 cups of water (1 g of salt to 1 L of

water).19. Shake or stir until the salt is completely dissolved.20. Pour a small amount of the salt solution into the wide-mouth jar.21. You'll tape the strip to a pencil and rest the pencil on top of the

jar so that the strip hangs into the jar.

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22. The goal is to have the end of the chromatography strip just touching the surface of the solvent solution, as shown in the drawing below.

23. Let the solvent rise up the strip (by capillary action) until it is

almost at the top, then remove the strip from the solvent. Keep a close eye on your strip and the solvent front—if you let it run too long the dye may run off the paper and become distorted.

24. Use a pencil to mark how far the solvent rose with a pencil.25. Allow the strip to dry, then measure the Rf value for each candy

color (or food coloring) dye component.

Observations

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Observations

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Observations

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Result

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Precautions

Do not eat any of the candies used in the experiment.

Chromatography paper should be spotted by the dye drop by drop.

Chromatography paper shoul not touch the sides of the beaker.

Organic solvent has to be taken in small amount.

Organic solvent should not touch the spot.

The dye should be concentrated enough. Capillary tubes should be used for

spotting the chromatography paper with the dye.

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Bibliography

http://www.arps.org/users/hs/thompsom/chemcom/unit_4/labs/Candy_Chromatography.pdf

http://www.sciencebuddies.org/science-fair-projects/project_ideas/FoodSci_p006.shtml

https://www.google.co.in/

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http://en.wikipedia.org/wiki/Chromatography

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