Rock Candy Lab: Connection to Chemistry

 Rock Candy Experiment

 

Materials:

• 1 cup clean water

• 2 cups granulated sugar

•  Glass jar (please try to bring your own)

•  Plastic wrap or paper towel

• Food coloring (if you would like)

• 1⁄2 tsp flavoring extract (if you would like)

•  1 cup measure

•  Wooden skewer and clothespins or cotton thread, pencil, tape and paper clip

•  Butcher thread

Procedure:

1.  Be prepared with your materials: wash a glass jar thoroughly with boiled water to clean it. Cut a length of thick cotton thread a few inches longer than the height of the jar, and tape it to a pencil. Place the pencil across the lop of the jar, and wind it until the thread is hanging about 1 inch from the bottom of the jar. Attach a paper clip to the bottom of the thread to weigh it and ensure it hangs straight down.

*Alternatively, you can use a wooden skewer as the base of your rock candy, and use clothespins balanced across the top of the jar to clip it into place.

2. Wet your thread or wooden skewer, and roll it in granulated sugar. The base layer will give the sugar crystal to grab when they start forming. Set the thread or skewer aside to dry while you prepare your sugar syrup.

3.  Place the water in a pen and bring it to a boil. Start to add the sugar one cup at a time, stirring after each addition. You will notice that it takes longer for the sugar to dissolve after each addition. Continue to stir and boil the syrup until all of the sugar has been added and it is all dissolved.

4.  Add the coloring colors (adding 1⁄2 tsp of extract).

5.  Allow the sugar syrup to cool for approximately 5 minutes and pour it into the prepared jar. Lower the sugared string or skewer until it hangs about 1 inch from the bottom.

6.  Carefully place the jar in a cool place, away from harsh lights, where it can sit undisturbed. Cover the top loosely with plastic wrap or paper towel.

7.  Start to see sugar crystals forming within 2-3 hours. If you have seen no change to your skewer or thread after 24 hours, tru boiling the sugar syrup again and dissolve another 1⁄2 cup of sugar into it, then pour it back into the jar and insert the string or skewer again.

8.  Allow the rock candy to grow until it is the size you want.

9.  Once it has reached the size you want, remove it and allow it to dry for a few minutes, then enjoy or wrap in plastic wrap to save it for later.

Rock Candy Connection to Chemistry

The experiment involving Rock Candy explores the consequences of introducing sand into water. Typically, sand settles at the bottom, being considered insoluble.

However, it's intriguing how certain solids appear to disappear when introduced to a solvent like water.

Take sugar, for instance. When solid sugar dissolves into liquid water, it forms a homogeneous solution known as an aqueous solution, as water is the solvent. Rock candy, a sweet treat, is produced through crystallization.

This process involves allowing a supersaturated sugar and water solution to crystallize on a suitable surface for crystal formation, such as a string. If you heat the water before adding the sugar, more sugar can dissolve, resulting in larger sugar crystals.

The term "solubility" is used to describe how well a solute, like sugar, dissolves in a solvent, and it depends on various factors, including temperature. "Precipitation" refers to the process where a substance emerges from a solution, similar to how sweet rock candy forms as a solid from water, rather than water falling from the sky. Consequently, it may take around 5 to 6 days for the crystals to develop as you'll need to wait for the water to evaporate.