At the time I’m writing this, many of us are stuck inside, quarantined, due to a virus. Being a health care worker, I obviously love science. But, prefer science that I can control!
My son and I have decided to try to do at least one science experiment a week while he’s home. We decided we would grow our very own salt crystals. It turned out to be a fun and easy experiment, and I wanted to share it with you! It doesn’t require a lot of time or work – mostly just patience to wait for the crystal growth!
Here’s how to grow your own salt crystals overnight:
Ingredients and Items Needed to Make the Epsom Salt Crystals
- a pencil
- cotton string
- scissors to cut the string
- something to weight down the string so it won’t float (we used an old washer tool)
- Epsom salt (Don’t have Epsom salt? You can use table salt and sugar, but the crystals will be different.)
- glass or mason jar
- measuring cup
- food coloring (optional)
My son wanted to make pink crystals, so we added some pink food coloring! You can make any color you want!
I also didn’t have plain Epsom salt. I had some that were mixed with essential oils for soaking sore muscles. I used it anyway, and it didn’t change the outcome. As I mentioned in the list, if you don’t have Epsom salt, you can substitute table salt or sugar. Changing the ingredients will change the crystal structure.
How to Make the Epsom Salt Crystals
- Step One: Measure one cup of Epsom salt and one cup of water and put them in your saucepan.
- Step Two: Heat the salt mixture until very warm (almost boiling). Turn that off and let it cool.
- Step Three: Tie your cotton string to the pencil and then measure to see where you would tie the washer or weight. You will want it to hang just slightly above the bottom of the glass. Tie the washer where you measure it.
- Step Four: Trim the excess cotton ends after you measure them.
- Step Five: Pour the cooled saltwater mixture into your glass or mason jar. Almost to the top.
- Step Six: Add any food coloring you would want to add at this time. (Totally optional.)
- Step Seven: Lie the pencil over the top and let the weighted string drop into the water.
- Step 8: Now, patience. Put in the refrigerator and let it sit for at least 12 hours.
- Step 9: Check out your crystals!!!!
The Science of Epsom Salt Crystals
Let your kids get out a magnifying glass and look at their crystals!
Discuss the science with your kids.
Epsom salt is the regular name for magnesium sulfate.
The water will have more salt than it can hold – it is supersaturated. When you cool the solution very fast, the conditions are unstable.
As your salt solution cools down, the magnesium sulfate atoms run into each other and form the crystal! They leave the water and attach to the string. The water will also be evaporating, which makes it more unstable and encourage even more crystal growth!
Science is so cool!
Other ideas for your STEM crystal experiment:
You could grow crystals in separate jars with three different ingredients: Epsom salt, table salt, and sugar. Encourage them to come up with a hypothesis for the jars. Which ones will grow the largest and why?
Let the kids record their scientific findings. Encourage them to describe the crystals with adjectives such as “needle-like”, “bumpy”, “big”, or “small”.
Did you enjoy this cool STEM experiment? Let me see the salt crystals that you and your children grew! Post them in the comments below, or email me pictures! I want to see it!
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