The process of forming a crystal is called crystallization. Crystallization commonly occurs when a solid crystal grows from a liquid or solution. As a hot solution cools or a saturated solution evaporates, particles draw close enough for chemical bonds to form. The slower the crystals grow and the larger the crystals become, the purer the substance will be.
This experiment demonstrates crystal growth from an aqueous solution using potassium aluminum sulfate, known as alum (tawas) which can be bought at the market or at any grocery store. Making alum crystals is an easy, fast, and fun science experiment. Making them is a safe process and only requires several household items. Using food coloring, you can alter the color of the crystals as well. With a few days’ time, you can make all the alum crystals you’d like.
Alum is non-toxic. Alum solutions can cause eye irritation. Wear goggles or safety glasses when working with the solution. Store your growing solutions in a place in which they will not be disturbed.
The materials used in this experiment are non-toxic and can be safely disposed of in the trash or liquids can be poured down the drain.
• 300ml hot tap water
• 5 tablespoons alum
• thread
• pencil, or ruler
• 2 clean jars
• spoon
• paper towel
Let’s do this!
Step 1: Pour 300 ml cup of hot tap water into a clean jar.
Step 2: Slowly stir in alum, a little at a time, until it stops dissolving. Don't add the whole amount; just enough to saturate the water.
Step 3: Loosely cover the jar with a paper towel (to keep dust out) and allow the jar to sit undisturbed overnight.
Step 4: The next day, pour the alum solution from the first jar into the clean jar. You will see small alum crystals at the bottom of the jar. These are 'seed' crystals that you will use to grow a big crystal.
Step 5: Tie the thread line around the largest, best-shaped crystal. Tie the other end to a flat object (e.g., popsicle stick, ruler, pencil, butter knife). You will hang the seed crystal by this flat object into the jar far enough so that it will be covered in liquid, but won't touch the bottom or sides of the jar. It may take a few tries to get the length just right.
Step 6: When you have the right string length, hang the seed crystal in the jar with the alum solution. Cover it with the paper towel and grow a crystal!
Step 7: Grow your crystal until you are satisfied with its size. If you see crystals starting to grow on the sides or bottom of your jar, carefully remove your crystal, pour the liquid into the clean jar, and put the crystal in the new jar. Other crystals in the jar will compete with your crystal for alum, so it won't be able to get as big if you let these crystals grow.
HERE IS MY CRYSTAL FROM DAY 1 TO DAY 5
So what are you waiting for? MAKE YOUR OWN CRYSTAL NOW!
References:
https://en.wikipedia.org/wiki/Crystal
http://sanyangfrp.com/know-cliparts.html
https://www.thoughtco.com/growing-a-big-alum-crystal-602197