Silicon makes up a quarter of the earth's crust by weight, and is found in most minerals, including sand. However, silicon does not exist in a free state; it is always in combination with other elements. Purification processes vary according to the use intended for the silicon, from glass to hyperpure silicon used for solid-state devices in electronics. There are several ways to make silicon crystals from sand, but only one of them is for DIY chemists, which can be done at home. The other processes involve temperatures over 3632 degrees Fahrenheit.
- Bunsen burner
- 3 tsp. magnesium powder
- 3 tsp. dry, sharp sand
- Test tube
- Heat-proof gloves
- 5 cups water
- Large laboratory flask
- 1 cup muriatic acid
- Funnel (optional)
Silicon crystals have a metallic luster and are a grayish color.
The only acid that affects silicon is hydrofluoric.
It is essential to add acid to water and not water to acid to avoid any danger of steam explosions.
Muriatic acid is highly corrosive. Although readily available from hardware stores, it must be used with caution.
Use a Bunsen burner to heat 3 level teaspoons magnesium powder mixed with 3 level teaspoons clean, dry sharp sand (not sand from a beach because of salt contamination) in a test tube. Wear heat-proof gloves if necessary. The magnesium takes oxygen atoms from the sand, leaving elemental silicon along with magnesium, magnesium oxide and magnesium silicide.
Remove from heat priot to purifying the mixture with an acid solution.
Pour 5 cups of cold water into a large laboratory flask. Add 1 cup of muriatic acid. Do not reverse these steps -- the acid must be added to the water.
Let the test tube cool for five minutes. Add the contents to the flask, using a funnel if the flask mouth is not wide enough. The reaction will be vigorous; therefore, place the flask on a worktop rather than holding it.
Allow the bubbling, foaming and fumes to settle, which should take less than one minute. The remains in the bottom of the flask are silicon crystals.
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