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05.05 Mixtures and Solutions: Lab Report

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fa lee

on 17 November 2014

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Transcript of 05.05 Mixtures and Solutions: Lab Report

Background Information and Research

Paper chromatography is a scientific technique way for dividing and finding mixtures that can be dyed. It is used for secondary colors in ink experiments. It can be used to test for contaminants in rainwater, analysis of narcotics, and detection of substances in urine and more.
Purpose

To show how you can separate different compounds from a mixture using variations in size of the molecules and repeated by the paper being used to separate the compounds.
Materials
Candy with a colored coating, like Skittles® or M&Ms® (4 different colors)
Rubbing alcohol or isopropyl alcohol
Coffee filters (2)
Tall glasses or plastic cups (2)
Pencil
Ruler
Tape
Foil or paper plate
Table salt
Water
Toothpicks or cotton swabs (4)
Measuring cups/spoons
Clean pitcher or 2-liter bottle
Data and Observations
Salt water: red-2.1in
blue - 2.4in
yellow-2.6in
orange-2.3in
Alcohol: red-2.3in
blue-2.3in
yellow-2.3in
orange-2.5in

Procedure
Coffee filters usually are round, but it's easier to compare your results if the paper is rectangular. So your first task is to cut the coffee filter into a rectangle measuring three cm by nine cm. You will need two of these strips to complete the lab.

Space four drops of water (or however many colors you are testing) equally distant on a piece of foil or plate. Position one candy of each color on the drops. Give the color about a minute to come off into the water. Dispose of the candy.

Using a pencil (do not use a pen), draw a line one cm (1/2 inch) from the edge of one end of one strip of paper.


Make four pencil dots (one for each color of candy you will be examining) along this line, about 0.5 cm (1/4 inch) apart. Underneath each dot, label the color of the candy you will test on that spot. You won't have space to write the whole color name, so try abbreviations like B for blue, G for green, etc.

Before you complete the rest of the lab, make a prediction of the components you expect to see from each candy color.
Dip a toothpick or cotton swab into one sample of colored water and dab the color onto the pencil dot for that color. Use a clean toothpick for each color. Try to keep each dot as small as possible. Allow the filter paper to dry, and then go back and add more color to each dot, repeating this step a total of three times for each color.

Prepare the salt solution by mixing 1/8 teaspoon of salt and three cups of water in a clean pitcher or 2-liter bottle. Stir or shake the solution until it is dissolved. This will produce a 1% salt solution.

Pour the salt solution into a clean tall glass so that the liquid level is 1/4 inch (0.5 cm).

Tape the strip to a pencil and rest the pencil on top of the jar so that the strip hangs into the jar. The goal is to have the end of the chromatography strip just touching the surface of the solvent solution, with the colored dots above the surface of the liquid. Make sure that the colored spots do not come in direct contact with the liquid in the bottom of the glass.

Capillary action will draw the salt solution up the paper. As it passes through the dots, it will begin to separate the dyes. When the salt water is 1/4 inch (0.5 cm) from the top edge of the paper, remove it from the glass and place it on a clean, flat surface to dry.

Repeat steps two through nine (using the second strip of paper and a clean glass) to test the same four colors using the alcohol instead of the saltwater solution at the bottom of the glass.

References


http://www.chemguide.co.uk/analysis/chromatography/paper.html
http://en.wikipedia.org/wiki/Paper_chromatography
05.05 Mixtures and Solutions: Lab Report
Discussion and Conclusion
A comparison of how each solution (salt water and alcohol) separated the pigments from each color of candy or ink type.

Which solution worked better at separating each of the pigments (it may be different for different candy colors or inks), and why do you think that is?
The alcohol worked the best with the salt water there was not a big difference in the colors .With the alcohol i can see the different pigments vanishing.

If you had allowed less time for the lab (stopping the separation process when the solution was halfway up the paper), how do you think that would have affected your results?
I wouldn't be able to see the pigments show because it took a while for it to show.

What pigment colors traveled farther up the paper? What pigment traveled the least? Was it the same or different when those pigments appeared in other candy colors or inks? Was it the same or different when separated by alcohol instead of salt water?
The black traveled the most far and the purple traveled the least.It was different when it appeared in other candy colors.It was also different when separated by alcohol instead of salt water because it showed different results.
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