Nothing says classic science experiments for kids like crystal experiments. Follow along with this tutorial to learn how to conduct your own borax crystals science project!
If you don’t want to do a full science project, you can also just do the experiment as a science demonstration for how crystals form and a lesson in supersaturated solutions, molecular bonds, and how temperature affects chemistry.
Borax Crystals Experiment
Try this borax crystals experiment to complete a borax crystal science project at home or school!
The Science Behind Borax Crystals
Crystals are molecules that bind together ionically (meaning that they are not flexible). Most crystal molecules form specific patterns of crystal formation. Borax crystals have a square shape to them.
Borax crystals can form when a supersaturated liquid containing borax powder is cooled. Hot water molecules are more active, so the molecules bounce around more and have more space between them.
This means that hot water can hold more of a powder than cold liquid. So as the liquid cools, those extra borax molecules must go somewhere, and they cling together to form crystals.
How borax crystals form
Dissolving borax powder into water creates a solution. When you follow the borax crystal recipe, you create a supersaturated solution. This basically means that there are more borax molecules inside the water than the water can hold.
As the water cools, it can hold fewer borax molecules, so the molecules cling together and form crystals.
Why do borax crystals form on pipe cleaners?
Borax particles are dissolved into the water as it heats. As the water cools, it is able to hold fewer borax particles. The particles must go somewhere, so if a pipe cleaner is suspended in the borax solution, the borax molecules come out of the water and cling to the pipe cleaner, forming crystals.
Hypothesis for growing borax crystals
If you are doing the borax crystal experiment as a science fair project, you need a hypothesis. You’ll also need variables.
There are two things you can test: the amount of borax powder inside of each jar, and the temperature of each jar. A common test is to see if crystals form faster in ice water, in the refrigerator, or in hot water.
The hypothesis in this case would be that one of the solutions would produce crystals the fastest. For the amount of borax variable, the hypothesis could be that more borax would produce larger crystals.
How to Make Big Borax Crystals
The secret to making big borax crystals is in the amount of borax that you add to the water. What you need to make is a supersaturated solution, with a lot of Borax powder.
In our borax crystal recipe, we use a ratio of one to two. One part borax powder for two parts water. This creates a mixture that dissolves almost entirely in the hot water, but a few borax powder grains remain in the bottom of the pot.
This is how you know that the solution is oversaturated.
When you follow this crystal recipe, you end up with big borax crystals that form in just a couple of hours. No need to wait overnight!
What you need for the borax crystals science project
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Borax Crystal Recipe
Follow along with these directions to make big borax crystals!
Make a supersaturated solution by boiling 4 cups of water and 2 cups of borax powder on the stove.
Once the powder is dissolved, remove from heat and allow the solution to cool until it is safe to handle.
While the liquid is cooling, form your pipe cleaners into whatever shape you want (we did stars).
Suspend the pipe cleaners inside the jars (don’t let it touch the bottom of sides of the jar) from a pencil. We always just use extra pipe cleaner to suspend the shapes, but you can also use string or fishing line.
Fill the jars with the cooled solution and wait.
If you want to make the crystals form even faster, put the jars in the refrigerator.
In about an hour or two, you’ll have big borax crystals!
Remove them from the jar, then allow them to dry on paper towels.
Once the crystals are dry, observe them with a magnifying glass.