| Orientation:
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The
purpose of this activity is to introduce the principles and
terminology of chromatography and demonstrate the separation
of the dyes in Sharpie pens with paper chromatography. |
| Supplies: |
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5 beakers
5 covers
Distilled H2O
100% isopropanol or 70% isopropanol
50 ml graduated cylinder
Transfer pipettes
5 strips of filter paper
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Different colors of Sharpie pens
Pencil
Ruler
Scissors
Tape
Safety glasses
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Access the Student Journal for Activity 6
Access the Student Presentation for Activity 6
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Activity
6 - Paper Chromatography
Preparing the Isopropanol Solutions
- Using a Sharpie pen, label your beakers
as follows: 0%, 20%, 50%, 70%, and 100%.
- Use the graduated cylinder to measure
the 100% isopropanol and distilled H2O for the
isopropanol solutions. The transfer pipettes may be used for
adding/removing small amounts. Prepare the following
isopropanol solutions: 0%, 20%, 50%, 70%, and 100%. The
following tables give the exact measurements necessary to make
each of the solutions. The first table is for solutions
starting with 100% isopropanol and second table is for
solutions starting with 70% isopropanol.
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Isopropanol Solutions
for 100% Isopropanol |
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0% |
20% |
50% |
70% |
100% |
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Isopropanol |
0 ml |
3 ml |
7.5 ml |
10.5 ml |
15 ml |
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Distilled H2O |
15 ml |
12 ml |
7.5 ml |
4.5 ml |
0 ml |
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Total Volume |
15 ml |
15 ml |
15 ml |
15 ml |
15 ml |
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Isopropanol Solutions
for 70% Isopropanol |
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0% |
20% |
35% |
50% |
70% |
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Isopropanol |
0 ml |
4.5 ml |
7.5 ml |
10.5 ml |
15 ml |
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Distilled H2O |
15 ml |
10.5 ml |
7.5 ml |
4.5 ml |
0 ml |
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Total Volume |
15 ml |
15 ml |
15 ml |
15 ml |
15 ml |
3. Pour each of these solutions into their labeled beakers as
you make them and cover them immediately to prevent the
isopropanol from evaporating.
Prepare the Chromatography Strips
4. Cut the filter paper into 5 strips that are 5 cm x 8 cm.
5. Using the pencil and the ruler, lightly draw a horizontal
line 1 cm above the bottom edge of each strip.
6. Label the strip on the top right-hand corner with the
number to the corresponding solution that it will be placed in.
7. Carefully spot each Sharpie pen on the starting line. For
the best results, gently touch the tip of the pen to the paper,
let it dry and spot it again on top of the first spot a few
time. Keep the spots small and space them out as much as
possible so that the colors will not run together as they
separate.
Developing the Chromatograms
8. Remove the covers and place the strips in the beakers.
Make sure the solution does not come above the starting line.
If you need to, remove some of the solution.
9. Start keeping time now for your observations.
10. Cover the beakers and let the strips develop until the
ascending solution is about 2 cm from the top of the strip.
Watch the solution moving up the strip (not just the colors’
movement). The colors will not move in some of the solutions.
The strips in low concentrations will finish first.
11. Remove the strips as they finish and let them dry on a paper
towel.
12. Dispose of the isopropanol solutions down the drain with
water.
13. Observe the results of the chromatograms.
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