Question

Calcium sulphate hemihydrate is known as ______.

Answer 1

Hint: In order to answer this question, to know the exact term for the Calcium sulphate hemihydrate, we should go through the hydration and the preparing mechanism of calcium sulphate and then we will also discuss the use of it.

Complete answer:
Calcium sulphate hemihydrate is known as Plaster of Paris. The hydrated state of calcium sulphate on heating yields plaster of paris.
Plaster of Paris is a white powdery chemical compound which is hydrated calcium sulfate that is usually obtained from calcining gypsum. Plaster of Paris is a traditional product that is used most widely for sculpting materials and in gauze bandages. Although we have seen many uses of this substance in our daily lives if we try to grasp its chemistry.
When dry, plaster of Paris does not shrink or crack, making it an ideal medium for casting moulds. It's also used to precast and retain pieces of decorative plasterwork for ceilings and cornices. While many modern orthopaedic casts are made of fibreglass or thermoplastics, it is still used in medicine to create plaster casts to immobilise broken bones as they recover. Some sculptors work directly in plaster of Paris because the pace at which the plaster sets lends the work an air of immediacy and allows the sculptor to rapidly realise the original idea. Gesso (usually made of plaster of Paris mixed with glue) was applied to wood panels, plaster, stone, or canvas to provide a ground for tempera and oil painting in the mediaeval and Renaissance periods.

Note:
The inorganic compound calcium sulphate (or calcium sulphate) and its hydrates have the formula $CaS{O_4}$ . It is used as a desiccant in the form of anhydrite (the anhydrous form). One hydrate is known as plaster of Paris, while another is found in nature as the mineral gypsum.