What is the process called when water leaves gypsum?

The process by which water leaves gypsum is known as calcination. Gypsum, chemically represented as calcium sulfate dihydrate (CaSO₄·2H₂O), contains water in its crystalline structure. When subjected to heating, particularly at temperatures ranging from 150 to 300 degrees Celsius, the water molecules are driven off, resulting in the formation of calcium sulfate hemihydrate (commonly known as plaster of Paris). This transformation involves the loss of water from gypsum, which is the essence of calcination.

In this context, calcination specifically refers to the thermal decomposition process where the water is expelled from gypsum, making it a crucial step in various construction and manufacturing processes. Understanding this process is essential for those involved in materials science, engineering, and construction, as it impacts the properties and applications of the end material.