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Spindles: How Can You Observe the Natural Shape of Epsom Salt Crystals?

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Author: Janice VanCleave

Problem

How can you observe the natural shape of Epsom salt crystals?

Materials

  • measuring cup (250 ml)
  • water
  • 2 tablespoons (30 ml)
  • Epsom salt
  • spoon
  • art brush
  • black construction paper
  • magnifying lens

Procedure

  1. Fill the measuring cup one-fourth (63 ml) full with water.
  2. Add the Epsom salt to the water.
  3. Stir well. The solution will look cloudy and will have few undissolved salt crystals on the bottom of the cup.
  4. Stir the water-Epsom salt solution with the bristles of the art brush.
  5. Spindles

    Spindles

  6. Remove the brush, and paint a section of the letter J on the sheet of paper.
  7. Stir the solution again with the bristles of the art brush.
  8. Remove the brush, and paint another section of the letter on the paper.
  9. Continue stirring the solution with the bristles of the brush and painting small sections of the letter, until the letter is completely formed.
  10. Place the paper near a sunny window for several hours.
  11. Use the magnifying lens to observe the letter on the paper every hour until the paper is completely dry.

Results

Results will vary depending on the humidity and the temperature of the air. It took three hours for the author's letter to dry on a day with low humidity and a temperature of about 68° Fahrenheit (20° C). At first, the edges of the letter dried, and tiny, shiny, clear crystals were seen. When completely dried, long spindles of clear, shiny crystals in starburst patterns formed the shape of the letter J.

Why?

Dissolving Epsom salt in water allows the molecules to separate and float freely through the water. As the water evaporates (changes from a liquid into a gas) from the solution, the Epsom salt molecules move closer together. The molecules all have the same shape, and they stack together like building blocks. As the water continues to evaporate, the salt molecules begin to stack in an orderly pattern, forming long, spindle-shaped crystals. The shape of the salt molecules determines the final shape of the crystals formed from the stacked molecules.

Try It With A Microscope

Microscope Procedure

  1. Place a drop of water on a slide.
  2. Dissolve one or two crystals of Epsom salt in the water.
  3. Allow the slide to dry, and observe under low power. Move the slide around to view different areas.

Microscopic Results

Long, needle-shaped crystals form patterns that look like feathers.

Let's Explore

  1. Do other crystalline solids have the same shape as Epsom salt? Repeat the original experiment, replacing the Epsom salt with table salt, alum, or sucrose (table sugar).
  2. Are the microscopic structures of other crystals the same as those of Epsom salt? Repeat the microscope procedure, replacing the Epsom salt with table salt, alum, and sucrose. Science Fair Hint: Make drawings of each observation, and display the drawings next to the crystals that were produced on the paper.

Show Time!

Grow large salt crystals by pouring ½ cup (125 ml) of warm tap water into a quart (liter) jar. Add and stir table salt, 1 tablespoon (15 ml) at a time, until no more salt will dissolve in the water. Cut a 2-inch (5-cm) wide strip of black construction paper. The height of the paper should be about one-half the height of the jar. Stand the paper strip against the inside of the jar. Place the jar in a visible place where it will be undisturbed. Allow the jar to sit for three to four weeks. Using a magnifying lens, make daily observations of the area around the paper. Photographs taken of the day-to-day changes can be displayed.

Check It Out!

Crystals come in many sizes, shapes, and colors. Some, such as diamonds, are more valued than others, but they all have their own quality and beauty. Find out more about crystals. What is the definition of a crystal? Are all solids crystals?

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