Polymers are made by combining many individual units called monomers into a
single large unit. The monomer unit in the bouncing ball polymer is polyvinyl
acetate:
-CH2CHCH2CHCH2CH- | | | O O O | | | C=O C=O C=O | | | CH3 CH3 CH3
When
borax is dissolved in water, some borate ions form.
Na2B4O7 + 9H2O -->
2Na+ + 2H+ +
4B(OH)4-
The borate ions form bridges
connecting the polyvinyl acetate chains to one another. The polymer formaed is a
non-Newtonian fluid. It has some liquid properties and some solid ones.
The Cost of Supplies 1 g of glue = $0.10 ($9 for 100 g) 5 g of
borax = $0.15,br> mixing vessel = $0.25 stirrer = $0.10 rental of lab
station = $1 per class hour rental of scale = $0.50 per class hour rental
of graduated cylinder = $0.50 per class hour
Procedure
Reasearch groups are formed and will compete to produce the
product with the most bounce.
Based on the production formula of 10 g
borax dissolved in 10 ml of wate and 10 g of glue mixed with 10 ml of water,
each group will determine the best formula to obtain the highest bounce. Each
group will prepare a presentation that includes: experimental procedure, ratio
of reagents, visual data charts, cost factor, and demonstration of bounciness.
The total cost of research may not exceed $15.