Rock Candy: Sweet Science | Science Fair Projects | STEM Projects (2024)

FAQs

What is a good hypothesis for rock candy? ›

The hypothesis is that if sugar water is left to evaporate, sugar crystals will form on a string or stick, creating a rock candy treat.

Sweets like Rock Candy are made through a process called crystallization. Sugar crystals form when you create a supersaturated solution of sugar and water — that just means there's more sugar than can be dissolved in the boiling water — and let it cool.

Putting a few grains of sugar on a stick or string promotes the formation of bigger crystals. This speeds up the candy-making. I had calculated that to make enough rock candy for that experiment, I would need to fill 52 plastic cups with a sugar solution.

Once a tiny crystal forms, it serves as a nucleation point. Other sugar molecules then glom on to it and make the crystal bigger. Seed crystals in the rock candy mix serve as this nucleation point, making the rock candy form faster.

The secret behind candy making lies in the skill of manipulating the inherent size and shape of a sugar crystal — more formally known as sucrose. As the compound is heated to different temperatures, it will move through several candy stages until the desired effect is achieved.

Contrary to studies performed at an industrial level, we found that solutions heated to 90°C experienced significantly greater rock candy mass growth than solutions heated to 60°C, 70°C and 80°C. Additionally, solutions heated to 60°C, 70°C and 80°C experienced nonsignificant differences in mass growth.

Pop Rocks^® are sugar candies with tiny pressurized bubbles inside them filled with carbon dioxide gas. When you place Pop Rocks^® in water, the sugar coating dissolves in water, and the gas and pressure are released. This also makes a popping noise, and leaves behind the sugar molecules.

If an impurity, food coloring, is added to the crystal solution, then the sugar crystals' growth will be affected.

Science of Candy: Rock Candy: What's Going On? What's Going On? Why does the string need to be soaked and then dried? The string will provide the surface on which the crystals will grow.

A supersaturated solution is unstable—it contains more solute (in this case, sugar) than can stay in solution—so as the temperature decreases, the sugar comes out of the solution, forming crystals. The lower the temperature, the more molecules join the sugar crystals, and that is how rock candy is created.

Why didn't my rock candy get hard? ›

The simple answer is that there is too much moisture in your candy.

It fails if you live someplace where the air is so humid that evaporation is very slow or if you place the container in a location where the temperature fluctuates (like a sunny windowsill) so that the sugar stays in solution.

Chemical Equation- The chemical equation for rock candy is C12H22O11(aq)--> C12H22O11(s). This is true because sucrose, table sugar, is an aqueous solution of sugar dissolving in water, and is formed into a solid of sugar molecules.

In general, candy is made by dissolving sugar into water to create a solution. Granulated sugar, the most common type used in candy-making, is sucrose, a disaccharide molecule made up of glucose and fructose. When you force these two molecules to break apart, a very tasty reaction occurs: caramelization.

The rock candy crystals form when water evaporates from saturated sugar water. This experiment may be carried out in the classroom, with your students participating. While the rock candy forms over several days, you and your students can observe and record the progress of the crystallization.