To grow a crystal of Potash Alum
Potassium alum is very soluble in water and crystallizes in an octahedral form with flattened corners.
- Potash alum
- Glass rod
- Piece of string
- Tripod Stand
Estimated Experiment Time
Approximately 2 hours to set up the apparatus and 1 week to make observations
- 1. Prepare a saturated solution of Potash Alum in a beaker by dissolving its finely-powdered form in distilled water.
- 2. Heat this mixture until all solids dissolve completely.
- 3. Allow the mixture to settle for a few minute.
- 4. Wait until crystalline formations appear at the base of the beaker leaving a clear liquid above it.
- 5. Transfer the clear liquid to another beaker.
- 6. From the deposited crystals, choose one that is well formed.
- 7. Suspend it from a glass rod in the saturated solution using a piece of string.
- 8. Examine the crystal each day and remove any other crystal that may be formed elsewhere in the solution.
- 9. Supplement the saturated Potash Alum solution from time to time to help the crystal grow in size.
- In order to get a large crystal at the end of the experiment, it is important that any other smaller crystals that may affect the growth of the one that is of interest to you be removed from time to time.
- The largest recorded crystals of potash alum that have been prepared are more than three feet in diameter.
- You may repeat the experiment with other salts like Copper Sulphate, Potassium Chlorate and Nitre for similar results.
At the end of approximately one week, a crystal of about one inch diameter is formed.
It is hence proven that in the presence of an abundance of more molecules of itself, crystals can be made to grow in size.
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