Calcium sulfate: a construction pro
How to make crafts from gypsum
Calcium sulfate has been used since ancient times — in building and construction, in sculpture, and even in medical services!
Observe safety measures when working with these compounds. Wear protective gloves, a mask, and safety glasses while conducting the experiment.
Reagents and equipment
- 70 g of calcium sulfate (alabaster);
- a silicone mold;
- a glass container;
- a food coloring;
- 100 mL of water;
- a spoon;
- 20% sulfuric acid solution;
- 20% calcium nitrate solution.
To obtain calcium sulfate dihydrate, simply mix solutions of sulfuric acid and calcium nitrate. In order to prepare a gypsum solution, mix it with water in a 7:10 ratio. You may also add a tiny bit of food coloring to the solution. Now, place the obtained mixture into the mold and leave it there for 20—30 minutes to solidify.
Calcium sulfate also occurs in nature in form of minerals — gypsum (calcium sulfate dihydrate) and its anhydrate (anhydrous calcium sulfate). In a lab, gypsum CaSO₄×2H₂O can be synthesized by mixing the solutions of sulfuric acid H₂SO₄ and calcium nitrate Ca(NO₃)₂, which yields a white crystalline precipitate.
Ca(NO₃)₂ + H₂SO₄ + 2H₂O = CaSO₄×2H₂O + 2HNO₃
If you were to add water to alabaster, it would eventually solidify with the formation of a durable material. It is often used in construction, in sculpture, and even for bone fixation in case of fractures.