How to Make Salt Crystals: At-Home Experiment

Instructor: Wendy McDougal

Wendy has taught high school Biology and has a master's degree in education.

In this chemistry project, we will make our own salt crystals by using Epsom salt and water. Watch as crystal formations grow in just a matter of hours and even make colored ones!

Introduction

Goal: To make salt crystals using Epsom salt and water
Age: Upper Elementary
Time to complete: Approx. 3-4 hours
Safety concerns: Salt will need to be dissolved in boiling water and this step should be done by an adult. Kids should handle the salt water solution once the water has cooled.

When you hear the word crystal, what comes to mind? Perhaps a fancy chandelier, or sparkling water glasses at a nice restaurant. Or maybe you have a rock collection that includes some varieties of crystals. Crystals can be found in a wide variety of types and formations. A crystal is simply a solid whose molecules are arranged in a regular, repeating pattern. And there is one type of crystal that you most likely have in your pantry and eat every day: salt.

Epsom salt, a type of crystal
Epsom salt

In this experiment, you will create your very own uniquely-shaped salt crystals. However, you will not be using the salt you eat every day, which is table salt. For this project, you will use a different variety called Epsom salt. By following some easy steps, you can watch your own crystals ''grow'' in just a matter of a few hours. You will observe the interesting shapes that form, and you can even color your crystals if you choose.

Materials

  • 1 cup Epsom salt
  • 1 cup water
  • Small saucepan
  • Clear glass jar
  • Food coloring if you want to make colored crystals
  • Cotton string
  • Pencil
  • 3 small paper clips

Steps

1. In saucepan, boil 1 cup of water (an adult should do this step).

2. Remove from heat and pour in salt.

3. Stir well until all salt is dissolved.

4. Let mixture cool in pan for about 20 minutes.

5. When your solution is no longer hot, pour it into glass jar.

6. If you would like colored crystals, add several drops of food coloring.

7. Tie one end of string to the three paper clips (these will weigh the string down to keep it in the solution).

8. Hang the paper clips with the string attached into the jar to see how long to make your string. The paper clips should hang just above the bottom of the jar.

9. Tie the other end of the string to the middle of your pencil at the desired length, and cut off any excess.

10. Place the end of the string with the paper clips into the solution and lay the pencil across the opening of the jar.

11. Place the jar into the refrigerator and let it cool for several hours. Check on it periodically. When do you begin to notice crystals forming?

12. When you are happy with the crystals that have formed, remove the string from the mixture. What do you observe? Do you have crystals? If so, what is their appearance?

13. To extend this project, repeat this process but use table salt or rock salt instead. How do these types of salt crystals differ?

Set up your jar like this to make your crystals
Jar for making crystals

Troubleshooting

If your crystals aren't growing, you may need to let them sit for longer. Be sure that your ratio of salt to water is 1:1.

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