Summer Research Program for Science Teachers
Far Rockaway H.S., Queens
Demonstrating Liquid Crystallization
Goal:
To illustrate applications of chemistry in our everyday world
Related Topics:
solutions, saturated, supersaturated, crystals, compounds, molecules, create a graph of crystal growth vs. time
Vocabulary:
solution, saturated, supersaturated
Materials:
water, copper sulfate, shallow dish, cotton thread, cardboard, glass jar
Procedure:
1. Dissolve the cooper sulfate in water
2. Pour a small amount into a shallow dish
3. Allow it to evaporate
4. Note date crystals begin to grow
5. Remove the largest crystal
6. Tie a cotton thread around it and suspend it from a piece of cardboard
7. Place the cardboard over the jar containing the remaining copper sulfate
8. Watch as crystals begin to form
Teachers Notes:
1. Copper Sulfate is poisonous. Wash hands after handling
2. As the water evaporates from the solution it reaches the point of saturation and the Copper Sulfate begins to form crystals
3. The crystal acts as a “seed” for further crystallization
4. Can grow salt crystals using this same method with a salt solution
Real World Applications:
Many modern calculators have a liquid crystal display (LCD). The liquid crystal is sandwiched between two thin pieces of glass in an LCD. The bottom material is a mirror, which reflects the light as it passes though the LCD. The outer material is a piece of conductive glass that changes the arrangement of the liquid crystals molecules beneath it, and stops light from reflecting back, creating the images you see displayed on the screen.
Resource: The Way Science Works by, Robin Kerrod and Dr. Sharon Ann Holgate
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