How to Make Copper Sulfate Crystals


Growing copper sulfate crystals is a popular and fun science experiment involving household items. Copper sulfate is available at chemistry and art supply retailers. The crystals develop as the water in the solution evaporates and forces copper sulfate molecules to bind together differently than they had before being dissolved in water: in a bright blue crystalline structure. Making a project out of copper sulfate crystals help students to understand the relationship that molecules have to one another.

Things You'll Need

  • Glass jars
  • Nylon string
  • Measuring cup
  • Spoon
  • Hot water
  • Copper sulfate powder
  • Eggs
  • Paper towels
  • Plastic container

String Method

  • Fill a glass jar with 0.5 cups of warm water. Stir in 2 to 2.5 tbsp. of copper sulfate.

  • Allow the jar to rest overnight in an area where the temperature remains stable, such as in a cupboard or on a table away from sunlight.

  • Pour the liquid contents of the jar into an empty container, being careful to leave the crystals that have formed at the bottom of the jar intact.

  • Pick one large crystal from the bottom of the jar. Tie a nylon string around the biggest crystal at the bottom of the first container. Tie the other end to a small dowel rod or pencil, and set the pencil across the mouth of the second jar that was filled with copper sulfate solution to suspend the chosen crystal and string within the solution.

  • Ensure that the crystal does not touch the sides or edges of the jar. Place the container back in the cupboard or on the table.

  • Leave the crystal in the solution for several days, or as long as you wish to get bigger crystals and the solution has evaporated.

  • Remove the crystal from the jar and set it on a paper towel overnight to dry thoroughly.

Eggshell Method

  • Crack an egg carefully to get two fairly even halves. Discard the inside of the egg and gently wash the shell in warm water.

  • Place the eggshells in a plastic container on a paper towel.

  • Pour 0.25 cups of hot water into a clean glass jar. Add 1 to 1.5 tsp. of copper sulfate to the water and stir with a spoon.

  • Carefully pour the copper sulfate solution into the halves of the eggshells. Place the container with the eggshells in a safe place, such as in a cupboard or on a sturdy table, away from sunlight.

  • Let the solution sit in the eggshells for several days until the desired amount of crystals have formed.

Tips & Warnings

  • You can pour out a portion of the copper sulfate solution from the eggshells to allow a better look at crystals as they form. The resulting crystals will be smaller, but is a good option for younger children that may not want to wait several days for a complete formation.
  • Copper sulfate is harmful if swallowed and should not be handled by young children.
  • Copper sulfate is an irritant. If it comes in contact with eyes or skin, wash the area immediately.


  • Photo Credit Ryan McVay/Stockbyte/Getty Images
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