Download the pdf of this lesson!
Download the SDS of this product.
When a small amount of this white powder is sprinkled into a liquid and water is added, it dissolves, forming a thick, mucous-like gel. When the gel is poured back and forth between two beakers, the gel readily siphons from the higher vessel to the lower one.
25 ml of a water soluble anhydrous alcohol (such as methanol or ethanol)
3-4 grams polyethylene oxide
2 - 600 ml beakers
Fluorescent dye such as fluorescein or rhodamine B (optional)
The gel can be disposed of in the waste paper basket (it's 99% water). The glassware can be rinsed with plenty of tap water and dried.
Polyethylene oxide, being a polyether, and containing an oxygen as every third atom in the chain, readily hydrogen bonds with water. This large number of oxygen and their two pairs of nonbonded 'p' electrons explains its high water solubility for its molecular mass (~4,000,000).
The long strands of gel are formed when these large molecules intertwine much like spaghetti and are cross-linked by water molecules attached to the oxygen on adjacent molecules. The result is a 'viscoelastic' gel. That is, like molasses, the gel has a high viscosity due to the large number of hydrogen bonds between the polymer molecules and water, and is elastic since these very long molecules can both straighten when stretched and slide past each other, forming fresh hydrogen bonds as they move.
1. http://sprott.physics.wisc.edu/demobook/into.htm, Demonstration 6.10 'Fluorescence'
2. Union Carbide product literature
3. Myerly, Richard C., J. Chem. Ed., 57, pp 437-8 (June 1980).
Was this review helpful?
Q & A