Question

What are the types of Plaster of Paris?

Answer 1

Hint: Plaster of Paris is made up of heated gypsum at a high temperature. The process of preparing it is described later in the content below. The chemical formula of gypsum is $CaS{O_4}.{H_2}O$ or $2CaS{O_4}.{H_2}O$ known as calcium sulfate hemihydrates.

Complete answer:
Plaster of Paris is made up of gypsum, the Plaster of Paris is a white color powder. It is a popularly used substance for sculpting, casting, and gauze bandage.
Manufacturing of Plaster of Paris takes place by heating gypsum in rotary kilns at a temperature of $300^\circ $ Fahrenheit. It is partially dehydrated. The chemical reaction which takes place is as follow: $2(CaS{O_4}.{H_2}O)\xrightarrow{{300^\circ F}}2(CaS{O_4}).{H_2}O + 2{H_2}O$. When we heat gypsum it loses the water molecule and turns into calcium sulfate hemihydrates. At this point, it is called Plaster of Paris.
Some properties of Plaster of Paris,
$ \bullet $ It is white powder.
$ \bullet $ When water is mixed with it, the gypsum crystals are produced which leads to set into a hard mass
$ \bullet $ It has an exothermic setting process and may be catalyzed by sodium chloride. It can be retarded by alum or borax.
$ \bullet $ At $473K$, Plaster of Paris forms anhydrous calcium sulfate known as dead burnt Plaster of Paris.
$ \bullet $ Plaster of Paris is not a waterproof substance. It is made waterproof by mixing other materials to be used in interior and exterior.
There are three types of Plaster of Paris.
Gypsum Plaster- This is produced by heating gypsum to a temperature of $300^\circ $ Fahrenheit. Also if heated below $392^\circ $ Fahrenheit, it turns into anhydrite. When we mix water with the gypsum plaster powder or anhydrite, it turns into gypsum.
Lime Plaster- The mixture of sand, calcium hydroxide and other inert fillers are lime plaster. Limestone is heated to make quick lime and then slaked lime is produced by adding water to it. Often called white powder or wet putty.
Cement Plaster- The mixture of suitable plaster, Portland cement, sand and water is called cement plaster. It is applied to the exteriors and interiors to obtain a smooth surface. A final layer of gypsum plaster is often added over the cement plaster.
Uses of plaster:
There are plenty of uses and applications across several sectors. From buildings, decoration to arts, medical and dentistry, Molding and casting agents, Radiotherapy, Decoration elements, Art and craft, In dentistry, for fireproofing, $3D$ printing, burial service. Plaster of Paris is used.

Note:
Plaster of Paris is dangerous if not properly handled. It can be harmful and dangerous, it is a calcium sulfate with silica and asbestos and impurities. Upon inhalation, it can lead to permanent lung damage and other ailments.
Alternative to Plaster of Paris is materials such as softwood, limestones, granite, sandstone, molding and casting clay, wax and other such substances can be excellent alternatives.