Experiment 1
| Analysis of the Color of Water Soluble Inks |  |
Purpose, Conclusions and Extensions
Purpose
Recall, if an ink
separates into several dyes of different colors, then those
individual dyes must have been responsible for the color of the
ink. Using this and the nature of the different subtractive
primary colors, it is possible to identify the origin of the
color of an ink.
Using the colors of the dyes and the value of the Rf
for a dye, it is possible to determine if two inks use a common
dye. In these experiments the individual inks from the different
pens are the independent variables and the colors of the spots
and Rf's are the dependent variables.
Finally, different solvents can change the effectiveness of a
separation by changing the values of the Rf's. This
can be investigated by chromatographing the inks several times
with different solvents. In this experiment the composition of
the solvent is the independent variable and the values of the Rf's
are the dependent variables.
There are three parts to the purpose of this experiment. In
general, they are to determine:
 | the origin of the color of inks in various pens by separating the dyes contained in the inks using paper chromatography. |
| if the dyes used are common to several inks by comparison of chromatograms and Rf's. |
| the effect of solvent composition on retention of dyes by varying the solvent used for the separation. |
At the beginning of your
report in your notebook, you must write the purpose of your
experiment. You can follow the format from above, but be
specific. For example, which inks are you studying? Which
solvents are you using? Use the purpose section to ask the
specific questions that you are trying to answer with your
experiment.
Conclusion
The conclusion section
which you include at the end of your report in your notebook is
very closely related to the Purpose section. In the Conclusion
section, answer each of the questions you wrote in your Purpose.
Base your answer on the data you reported in the Results section.
For example,
| Give a specific explanation of the origin of the colors observed for each ink. In your explanation refer to the subtractive primary colors which are used in the inks. How do these primary colors result in the color of the inks? |
| Are there any dyes which are used in more than one ink? How do you know this? Use the colors and Rf's as evidence to convince the reader that your conclusion is supported by evidence.. |
| How does the change in solvent affect the separation? Refer to the specific values of the Rf's to illustrate your conclusion. Does this tell us anything about how the dye prefers the paper or the moving solvent? |
Extensions
Can you suggest any extensions to this experiment? Think about changing the independent variables and the dependent variables that you could measure or observe. This may suggest new experiments that you could propose for your project or try later for your classroom.
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