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How to Make Salt Crystals
Creating crystals of table- or Epsom salt or sugar can be an excellent idea for your next science fair project. The process is simple and needs minimum adult supervision.
Salt (sodium chloride) consists of tiny cubic crystalline structures where the molecules are arranged in an orderly, geometric and repeating pattern, and you can grow your own salt crystals pretty easily.
Salt Crystal Experiment
Here are the instructions on making salt crystals. The method is similar for Epsom and sugar as well.
- ½ cup water
- 3 cups salt
- Food Color
Growing Homemade Salt Crystals
- Heat about 120 mL of water in a pan. Heating should continue until the water begins to bubble.
- Stop heating the pan.
- Take about 60 -120 mL by volume of salt and stir the water until it is clear. If you do not find any undissolved particle even after stirring, then add more salt and stir. Keep doing this until you find the grains do not dissolve anymore and pop out of the solution. Under this condition, the solution is said to be supersaturated as it contains more salt than the water can accommodate.
- Pour the contents of the pan in a jar being careful not to pour out any undissolved residue.
- Add a few drops of food color to the solution.
- Take a pencil long enough to lie across the mouth of the jar and tie a string at its center. You can also use a popsicle stick or any small stick for serving the purpose.
- Cut the part of the string hanging from the pencil to an appropriate size. The free end of the string should not touch the bottom of the jar lest the crystals formed are small and lumpy.
- Place the pencil on the jar with the string immersed in the solution. If the pencil wobbles, tape it to the jar. The string should not lean against the walls of the container since this can inhibit the augmentation of the structures.
- Keep the arrangement in a safe place free of any disturbance.
- If you want to grow crystals fast, place the jar in the sun or near a fan. The lump so created will, however, consist of small crystals as they stop increasing size after a certain period. If you want a large single crystal instead, keep it in a cool, shady place devoid of movement and vibration.
- Those of you experimenting with Epsom can refrigerate the jar for a quicker growth of the needle crystals. Alum crystals become visible very quickly, sometimes taking shape within a few hours. But the full process might take a couple of days. Table salt crystals start forming in a couple of days; maybe a week and take around two weeks to finish off.
- Check back every day to track the crystallization. The rate of growth increases with cooling of the water and evaporation.
You can try to make crystals with different substances and compare their rate of growth, color, taste, size, duration of formation, etc. Also test crystallization using tap water and distilled water. In this case, your hypothesis could be crystals of salt grow faster in tap water. After the experiment, note down your observations and tally them with your hypothesis.
Published on August 21st 2015 by Papiya Dutta under Science Fair Projects. Article was last reviewed on 16th July 2020.