Download Chemistry 8: Paper Chromatography

Chemistry 8: Paper Chromatography
Students will learn about chromatography in general and use paper chromatography to explore
the composition of various inks. We begin with a discussion about chromatography and its various
forms and explain how this powerful tool can help distinguish between two or more compounds.
Audience:
6th‒8th, the activity could be performed with younger students, but an explanation of the mechanism would be
quite difficult to convey.
MCAS:
H.S. Chem 4.5“Identify how hydrogen bonding in water affects a variety of physical, chemical, and biological
phenomena (e.g., surface tension, capillary action, density, boiling point).”
H.S. Chem 7.1“Describe the process by which solutes dissolve in solvents.”
Indirectly
6th‒8th PS6 “Differentiate between an atom (the smallest unit of an element that maintains the characteristics
of that element) and a molecule (the smallest unit of a compound that maintains the characteristics of that
compound).”
6th‒8th PS8
“Differentiate between mixtures and pure substances.”
Vocabulary:
Terms to know beforehand:
Terms defined in lesson:
• atom—means “indivisible,” the smallest bit of matter with specific chemical
• Chromatography
properties e.g; gold atoms vs. oxygen atoms
• Dissolve
• compound—chemical formed from atoms of two or more elements.
• Solute
• mixture—separable blend of multiple elements/compounds; see C04 below.
• Solution
• molecule—a group of atoms joined together as a compound (H 2O) or • Solvent
elemental form (O2, O3)
• Suspension
• diameter—line which divides a circle in half
• parallel—lines that never cross; contrast perpendicular, which intersect at
right angles
Related Modules:
C04‒Separation of Substances introduces/reviews the topics of atoms, elements, and mixtures. This is strongly
recommended as a pre-req for audiences unfamiliar with basic chemistry such as the indirectly addressed
MCAS standards above e.g; for 6th graders. This lesson also introduces much of the vocabulary above.
In C02‒Chemical ID the variable miscibility of several common powders in different solvents is used to help
identify an unknown chemical. The end of lesson debriefing for ES01‒Wondrous Water includes an optional
demonstration and discussion about solubility of different substances
Safety:
Like all alcohols, the isopropanol used in this lesson is toxic. Although only mildly so, it still should not be
consumed. The lesson includes an optional but brief discussion about the toxicity of common alcohols.
Preparation:
Review the basics of atoms & molecules using ball-and-stick drawings/models. Consider exploring the structure
of paper(s) and its role in capillary action.
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Additional Resources:
http://youtube.com/watch?v=ASLUY2U1M-8 — Video1 (3:52), How polarity makes water behave strangely
http://youtube.com/watch?v=5uuQ77vAV_U — Video (5:35), Exploiting polarity to purify water
http://youtube.com/watch?v=ASLUY2U1M-8 — Video (13:34), Aqueous solutions
http://youtube.com/watch?v=QXT4OVM4vX — Video (9:46), Chemical bonds
http://youtube.com/watch?v=PVL24HAesnc — Video (10:46), Polarity
http://youtube.com/watch?v=PPJ0Khs7uWs — Video (8:17), Superhydrophobic & superhydrophilic surfaces
http://youtube.com/watch?v=DZrjXSsfxMQ — Video (5:05), Demos of a commercial superhydrophobic coating
There are similar commercial coatings and this is not an endorsement of Rustoleum's product.
Repeat demonstrations at your (clothing/electronics) own risk.
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https://sciencefromscientists.org/cool-stuff/youtube-for-schools
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