Growing Inorganic Crystals
Be sure to have parental supervision and follow the safety precautions appropriate for the reagents used in the experiment.
Potassium aluminum sulfate dodecahydrate
Colorless. Cubic system.
KAl(SO4)2·12H2O
Make the following supersaturated solution:
1 a. 4 ounces of alum in 567 milliliters (19 ounces) of water
or b. 20 grams per 100 milliliters of water
Add to the saturated solution:
2 a. 22 grams alum or b. 4 grams alum per original 100 milliliters of water
If the crystals grow too quickly they will have many veils and appear milky. To prevent this, reduce the amount of alum added in step 2.
Reference: Crystals and crystal growing. Alan Holden and Phylis Morrison, The MIT Press, 1982,ISBN 0-262-58050-0
Borax
Na2B4O7·7H2O
Add one teaspoon of borax to 4 ounces of very hot water.
Stir until borax is completely dissolved. When this solutions cools to room temperature little borax crystals will grow.
Alum
NH4Al(SO4)2·12H2O
Add 4 teaspoons of alum powder to four ounces of hot water.
Stir until alum is completely dissolved. Place a paper towel over the top of the jar containing the solution and secure with a rubber band. This will prevent dust from entering the solution but allow for evaporation. After a period of time, given adequate evaporation, alum crystals will appear.
Epsom Salt
MgSO4·7H2O
Add 6 teaspoons of epsom salt to 2 ounces of hot water. Stir until epsom salt is completely dissolved. If all the salt does not dissolve, add a very small amount of water and stir until all the epsom salt is dissolved. Place a paper towel over the top of the jar containing the solution and secure with a rubber band. This will prevent dust from entering the solution but allow for evaporation. After a period of time, given adequate evaporation, epsom salt crystals will appear.
Reference: Crystals - A Handbook For School Teachers by Elizabeth A. Wood 1972. Written for the Commission on Crystallographic Teaching of the International Union of Crystallography.
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