Glass Submitted By: Mélanie St-Georges

Overview

Topic Area(s) Age Cost Time Complexity Objective Science: 8-12 1 ½ hour Preparation= 2/5 crystallization Execution= 3/5

Hook

Have you ever noticed how easy glass breaks in movies? It’s because it’s not real glass, it’s a sugar mixture!

Necessary Background Information

When we boil sugar glass, we want to prevent the sugar from crystallizing. Crystallization is when there’s a formation of little precipitations that look like crystals. We want to avoid having a crystalline state and would want a clear glassy state. The glassy state is desired for several reasons: rapid dissolution, uniform dispersion of flavour and color and the ability to be molded into the desired shapes. We achieve the glassy state by making sure that all the raw materials are mixed and heated to ensure that all sugar crystals are dissolved. This sugar is concentrated rapidly by boiling at high temperature to low water content. The speed of concentration is critical to production of a stable sugar glass. If evaporation is too slow, crystallization can occur. Also, when cooling down, be careful of the crystals on the side of the pot falling into the mixture. If the sugar gets a crystal in it, it will crystallize in a flash. The (pure ) and the cream of tartar (an acid to break down some of the sugar) will help you avoid that messy possibility, but it is still a possibility. They are used to prevent the sugar from crystallizing. It does this by breaking down some of the sugar molecules at the single oxygen atom, creating single molecules of and fructose. The corn syrup is mostly glucose, and acts as a buffer between molecules preventing them from joining together in one giant mass and ruining your crystal clear confection. Since we are using corn syrup, you can omit the cream of tartar, but I like to hedge my bets, and I've found that I get a better result more consistently (less likely to flash crystallize when the heat is off) when I use the cream of tartar. Here is a polymer of sucrose molecules, they are joined together by the oxygen atom. This is what we do not want, since it would create a crystalline:

And this is single molecules of sucrose. This is what we do want!:

Materials

- 1/2 C Water - 1 C Sugar - 1/4 C Corn Syrup - the clearer the better - pinch of Cream of Tartar - Pot - Spoon or spatula - Hot plate - thermometer

Safety Considerations

It is 300 degrees, and it sticks to everything. It is a very good way to get a very nasty burn. Please exercise caution when dealing with this stuff

Procedure

1. In the sauce pot, combine the water, sugar, corn syrup, and cream of tartar. Stir to dissolve as best as you can. The heat will finish dissolving it. 2. Turn the heat on high on and let it come to a boil. 3. When the mixture comes to a boil, it is time to put in the candy thermometer. You want it to be about 302 degrees Fahrenheit (150 degrees Celsius). This takes awhile. 4. When the temp reaches 302 degrees F, remove it from the heat, and set it aside to cool a bit before working with it. This will also help get some of the air bubbles out. 5. Pour it in the aluminium plate and let cool.