One of my favorite parts of teaching is creating fun seasonal learning activities for my kiddos. We particualrly love doing STEM activities and science experiments for kids. Today, we’re bringing a twist on how to make crystals without borax by making these fun salt crystal rainbows!
We always like giving our science experiments a seasonal twist- and this time, we’re completing St. Patrick’s Day science by making rainbows from salt!
Follow along to learn how to make your own crystals without borax using salt. This experiment is perfect for St. Patrick’s Day STEM activities, rainbow science experiments, or spring science experiments!
SALT CRYSTAL RAINBOWS SCIENCE EXPERIMENT
HOW DO YOU MAKE CRYSTALS WITHOUT BORAX?
What is the secret to creating crystals fast? The secret is creating a super-saturated solution of salt water. A super-saturated solution is simply adding enough salt to the boiling water so that it is no longer able to dissolve. The more saturated the solution, the faster crystals will form.
Using enough salt will produce visible crystals in under an hour! Watch our pot of gold salt crystal video to see how to make your very own crystals without borax.
THE SCIENCE OF SALT CRYSTALS: HOW DO SALT CRYSTALS FORM?
Salt crystals form when a solution of water becomes over-saturated with salt. When you create a super-saturated solution, the salt crystals must go somewhere when the mixture cools and the water starts to evaporate. The furry pipe cleaners make the perfect surface for salt crystals to cling to. Over time, the crystals accumulate into larger and larger crystals.
As the water evaporates, the salt crystals cling to one another, forming large squares of salt, just like are found in nature.
Kids will be fascinated by the ionic bonds that salt makes, creating perfect squares and rectangles every time. The reason salt crystals make such perfect square shapes are due to the type of molecular bond that salt crystals have.
Salt bonds ionically, meaning that the bonds are inflexible. The molecules bond using the same pattern over and over, which creates a stable shape that is the same every time.
Next Generation Science Standards (NGSS) Alignment
Use this experiment to complete the following NGSS goals:
- 5-PS1: Matter and Its Interactions
- 5-PS1-4: Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
- PS1A: Structure and Properties of Matter
- PS1B: Chemical Reactions
HOW TO GROW CRYSTALS WITHOUT BORAX
This fun salt crystal rainbow science activity shows how salt crystals form with a fun St. Patrick’s Day science twist!
What you’ll need to make salt crystal rainbows:
If you buy using these links, I will earn a comission on the sale.
The Mason Jar Scientist: 30 Jarring STEAM-Based ProjectsBall Glass Mason Jar with Lid and Band, Regular Mouth, 12 JarsAcerich 300 Pcs Colored Pipe Cleaners Chenille Stems for DIY Art Craft Decorations (6 mm x 12 inch)Morton Iodized Salt, 26 oz, Pack of 4Ticonderoga Wood-Cased Graphite Pencils, #2 HB Soft, Yellow, 96 Count (13872)AmazonBasics Pre-sharpened Wood Cased #2 HB Pencils, 150 Pack
Don’t forget to grab your growing crystals lab worksheet to go along with the salt crystal science experiment!
HOW TO DO THE SALT CRYSTAL SCIENCE PROJECT
- Boil enough water to fill as many jars as you have (we did 1 jar per rainbow).
- Add enough salt so that crystals form on the surface of the water. It will look like a sheet of thin ice.
- Remove the water from the heat and let the mixture cool.
- While the water is cooling, form your rainbows using pipe cleaners. Start with the purple or pink pipe cleaner and make a backwards rainbow with purple, blue, green, yellow, orange, and red as the top color. Twist the ends of the pipe cleaners together to hold the rainbow shape (Once the crystals form, the rainbows will hold their shape better).
- Attach the rainbows to the pencils with another pipe cleaner.
- Pour the salt water into the jars.
- Lower the rainbows into the salt water solution.
- Wait a few hours for salt crystals to form. Leave the crystals in the solution for longer to make bigger crystals. After two hours, small salt crystals will start to form. You can leave the pipe cleaners in the saltwater solution for 2-3 days, but if you are in a hurry, the crystals will be visible and ready to study within an hour or two. These salt crystal rainbows were left in the salt water solution for 2 hours. Our salt crystal pots of gold were left in the solution for 2 days.
Love Science and STEM?
Complete the science fun with these science experiment e-books!