How does sugar and water make rock candy?

1. Supersaturation:

* Dissolving Sugar: You start by dissolving a lot of sugar into hot water. The hotter the water, the more sugar it can hold.

* Supersaturated Solution: Eventually, you reach a point where the water can't dissolve any more sugar. This is called a supersaturated solution. It's like a sponge that's completely full of water, and there's no room for more.

2. Crystal Formation:

* Cooling and Nucleation: As the supersaturated solution cools, it becomes unstable. The sugar molecules have nowhere else to go, so they start to clump together. These small clumps are called nuclei.

* Crystal Growth: More sugar molecules in the solution attach themselves to these nuclei, making them grow bigger and bigger. These are the rock candy crystals!

3. Controlling Crystal Growth:

* Time: The longer the solution sits, the more time the crystals have to grow.

* Temperature: The slower the solution cools, the larger the crystals can grow. Fast cooling leads to many small crystals.

* String or Stick: You provide a "seed" for the crystals to grow on, like a string or stick. The crystals will attach to the rough surfaces of the string or stick, forming your rock candy.

In a nutshell:

Rock candy forms because the excess sugar in a supersaturated solution has to go somewhere. It finds a "home" on the string or stick, growing into beautiful, sugary crystals!