Rock Candy Your Body: Exploring Crystallization
Students see and learn how crystallization and inhibition occur by making sugar crystals with and without additives in a supersaturation solution, testing to see how the additives may alter crystallization, such as by improving crystal growth by more or larger crystals. After three days, students analyze the differences between the control crystals and those grown with additives, researching and attempting to deduce why certain additives blocked crystallization, showed no change or improved growth. Students relate what they learn from the rock candy experimentation to engineering drug researchers who design medicines for targeted purposes in the human body. Conduct the first half of this activity one day before presenting the associated lesson, Body Full of Crystals. Then conduct the second half of the activity.
Sugar crystals made from a supersaturated solution of sugar in water after three days.Copyright 2014 Megan Ketchum, University of Houston
Crystals are present in many forms in the human body, with certain ones causing damage, such as kidney stones and cataracts. When a person breaks a bone at a joint, the casted (immobile) bone begins to calcify at some point. Calcification is the crystallization of calcium salts occurring when bone forms. This calcification can cause bony deposits on the joints, limiting the body's capability for motion. Engineers and doctors have studied this process and developed an improved method of treatment: remove the cast early and use physical therapy to maintain mobility. To understand this process, examine how crystallization occurs and how impurities and inhibitors affect crystallization.
After this activity, students should be able to:
- Explain how crystallization is affected when inhibitors are introduced.
- Determine the properties of the additives that cause inhibition, no change or improved crystal growth.