Rock Candy Sticks
Get ready to watch some cool crystals grow! And when you're done, you can eat them or give them away as Christmas gifts!
What You Need:
- 1/2 cups of white sugar
- 1 cup of water
- Small plate
- A spoon
- A glass
- Wax paper
- Several small clean jars
- Cake pop sticks or wooden skewers
- Food coloring (optional)
- An adult to help you
What You Do:
- Fill a glass with water, pour some sugar on a small plate, and lay out a sheet of waxed paper. Dip one end of each stick (cut pointed ends off if you use skewers) into the water and then roll it in the sugar, tapping it gently to remove excess. Set each stick to dry on the waxed paper.
- Pour the water into the saucepan and add the sugar. Stir it well until no more sugar will dissolve. If it all dissolves, add more sugar until you can’t get any more to dissolve even after stirring for several minutes. (You now have a saturated sugar solution.)
- Ask an adult to help you heat the sugar mixture on the stove until it boils, stirring the whole time. Turn the heat to medium-low and keep stirring until all the sugar dissolves. (Now you have made a supersaturated solution!)
- Keep cooking the liquid and stirring it until it becomes clear, but not for more than 5 minutes, or it will get too hot and turn into hard candy! Turn off the stove as soon as it starts to look clear.
- Move the pan off the heat and allow it to cool down until the pan is no longer hot (the sugar solution will still be slightly warm).
- Have an adult slowly pour the thick sugar solution into the jars. Fill each about 2/3 full, or enough so that sugar solution will cover several inches of your sugar-coated sticks.
- Add 5-6 drops of food coloring to each jar and stir. (Optional: Only do this step if you want to make different colors of rock candy!)
- Once the solution is cool and the sugar-coated sticks are completely dry, place several sticks into each jar.
- Carefully move the jars to a place where they won't be disturbed. Check them every other day and gently stir the sticks around in the sugar solution to break up any large crystals forming on the surface.
- Within a few days, you should start to see crystals growing on the sticks. After about one week, you will probably have a lot of crystals. When your "rock candy" crystals are as big as you want them to be, take them out of the jars and set each color of candy in a clean glass to dry.
- Once they are dry, you can wrap in cellophane food wrap and tie with ribbon for a sweet Christmas gift!
In step two you made a saturated solution -- there was so much sugar in the water that it couldn’t dissolve any more sugar and some was left in the bottom of the pan. Once the saturated solution started to heat up, the water was able to dissolve even more sugar and a supersaturated solution was formed in step three. Then, as the solution cooled, the sugar molecules in it started to join with the sugar molecules on the sticks. The sugar on the sticks are called “seed” molecules and the sugar molecules in the solution attached themselves to the seed molecules. Meanwhile, the water in the solution started to evaporate or dry up into the air, leaving only sugar molecules behind. More sugar molecules gradually joined with the ones already on the stick, forming larger crystals. Because all of the solute molecules are the same (they are all sugar), they all form the same shape of crystals and they all stick together, making a big chunk of sugar crystals that are pretty to look at and tasty to eat!
Note that this is a special science project that is safe to eat because you only used food products, not any chemicals, and you used clean dishes from your kitchen. Never eat any experiment unless it is made entirely out of food and you only used clean dishes to prepare it!
Sparkly Crystal Ornaments
In this project, you use a chemical called borax to grow crystals shaped like snowflakes, stars, or candy canes. Then you can use them as pretty decorations!
What You Need:
- Wide-mouth jar
- Pipe cleaners
- A pencil
- 1-cup measuring cup
- Food coloring (optional)
- Glow-in-the-dark paint (optional)
- Ribbon (optional)
What You Do:
- Twist pipe cleaners into whatever shape you'd like (we chose a simple star). Note: Make sure your pipe cleaner shape will fit easily into your jar with plenty of space around the mouth of the jar as the shape will be slightly wider once crystals have formed on it, making it harder to remove!
- Tie a piece of string to one point of the shape. Tie the other end around the middle of a pencil.
- Hang the shape in the jar with the pencil resting across the mouth of the jar. Make sure that it hangs without touching any part of the jar. Take it out of the jar and set it aside.
- Use a 1-cup measuring cup to count how many cups of water you need to fill your jar about 3/4 full. Then microwave the jar of water for 3-5 minutes or until it begins to boil. Have an adult carefully take the jar out using hot pads (the jar will be very hot!) and set it on a heat-safe surface.
- For every cup of water you put in the jar, measure three tablespoons of borax. Stir the borax solution with a spoon until as much of it dissolves as is possible. If you don't see any tiny pieces of borax floating around in the jar, add another tablespoon and stir. This will make a saturated solution.
- Hang your pipe cleaner shape in the jar so that it is completely covered in the solution. Let it sit overnight. Gently remove your now crystal-covered shape in the morning and let it dry by setting it in a dry glass.
- Optional: To make colored crystals, use colored pipe cleaners and add 5-10 drops of food coloring to the solution in step five. To make your snowflakes glow in the dark, paint the pipe cleaner shape with glow-in-the-dark paint in step one and let it dry completely before continuing. Once the crystals have dried, cut off the string and tie a ribbon to one point of your crystallized shape to make a Christmas tree ornament! These ornaments are fairly sturdy and make lovely Christmas gifts for friends, teachers, or family members.
Just like in the rock candy project, you made a saturated solution of borax, which is a chemical that forms crystals when the conditions are right. By mixing it with hot water and letting it cool and having something for the borax (solute) molecules to attach to (the pipe cleaner shape), you gave the solution the right conditions to grow crystals! Once the crystals started to grow on your shape, more and more crystals formed around them. Ice crystals that real snowflakes are made of are not quite like these borax crystals, but they do look sort of similar and they both are pretty and sparkle when light shines on them. Real ice crystals are made only of water. The difference is that they are formed when water vapor in clouds freezes and falls to the ground as snowflakes! Frost is another form of ice crystals that you might see on windows and grass on cold mornings. To learn more about snow and ice crystals, check out our Snow and Hail article.
Salt vs. Sugar
How can you tell the difference between sugar and salt? They're both crystals and they look very similar - they are both small, white-colored grains. Of course if you tasted each of them, you would know right away which one was salt and which was sugar because they taste very different. In this project you will find out how to tell sugar and salt apart just by looking at them!
What You Need:
- A teaspoon of table salt
- A teaspoon of white granulated sugar
- Two sheets of black construction paper
- A magnifying glass
- Crystals worksheet
What You Do:
- Put a teaspoon of salt on one sheet of black paper and a teaspoon of sugar on the other.
- Use your fingers to spread the grains apart a little so you can see them better. Now look closely at the grains on each sheet of paper and compare how they look. Do you notice any differences between the two?
- Now use your magnifying glass to look up close at a few grains of the salt. What shape are they? Are they all about the same shape? Draw their shape in the correct spot on the worksheet.
- Now take a look up close at a few grains of the sugar. What shape are they? Are they a different shape from the salt crystals? Do you notice anything else that makes them look different from the salt? Draw their shape on the worksheet.
Sugar and salt grains are actually tiny crystals. If you were to make a saturated solution of each of them, you would be able to see them grow into much larger crystals, but they would always have the same shape as these tiny crystals do! The salt crystals are cube shaped (like dice) and have six sides. The sugar crystals are very rough looking and are shaped more like rectangles with pointed ends. Most of the crystals are the same shape and size and look very similar to each other, but you probably saw a few crystals on your paper that looked a little different. Those crystals probably had pieces broken off of them, or there might even be more than one crystal stuck together, making them look different from the others. Also, the coloring of the crystals is a little different. Sugar crystals look very clear and sparkly while salt is duller and looks more white-colored or frosted.
Can you tell if the picture above is of salt or sugar? It's Sugar!