L8 Handout - # Chem 151 Lab Practical Midterm Ink...

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# Chem 151 Lab Practical Midterm Ink Composition: A case of chemical analysis Ink is frequently associated with writing. But the use of ink may very well predate recorded history, or even mankind itself. It is quite possible the materials used by Neanderthals to produce their cave drawings were inks. All inks are chemical concoctions that can be rather easily separated into the individual components and characterized. With this experiment you will use a common commercial ink pen to demonstrate your understanding of chemical separations and the characterization of chemical substances. Educational Objectives: A student who has successfully completed this experiment will be able to # separate the colored components of a mixture using column chromatography, # characterize the colored components of a mixture, and # write a suitable report. Experimental Objectives: A student who performs this experiment is asked to # separate the ink from a commercial marking pen using column chromatography, # characterize the colored components using absorption spectroscopy, an # construct a report detailing the results of the analysis. Background Inks are mixtures of a number of chemical compounds dissolved in a solvent. The main components are pigments that impart color to the ink. Other components contribute to other characteristics of the ink such as viscosity, permeability and permanence. The development of inks is a thriving business concern. Companies like Hewlett-Packard employ thousands of chemists and engineers to work on developing new and better inks and ink delivery systems. When an ink is applied to a surface the solvent evaporates leaving the pigments and other components behind. For a permanent ink the pigments should adhere to the to the 1 O
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O PRACTICAL MIDTERM surface. It also helps if the solvent and pigments are able to soak into the surface. An erasable ink will have only weak bonds to the surface. The pigments used in an ink must have the desired color
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L8 Handout - # Chem 151 Lab Practical Midterm Ink...

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