Question

What are the different types of plaster of paris?

Answer 1

Plaster of Paris:

1. It is chemically known as Calcium sulfate hemihydrate.
2. It is a white powder that is slightly hydrated with Calcium sulfate.
3. Gypsum is formed by heating at $373\mathrm{K}$. $$\begin{gathered} {\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)\stackrel{∆}{\to }{\mathrm{CaSO}}_4.\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)+\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.{\mathrm{H}}_2\mathrm{O}\left(\mathrm{aq}\right) \\ \mathrm{Gypsum}\mathrm{Plaster}\mathrm{of}\mathrm{Paris} \end{gathered}$$

Uses of Plaster of Paris:

1. It is mainly used for medical purposes to make a plaster cast to immobilize the broken bone with the help of fiberglass or thermoplastics.
2. As well as holding plasterwork on ceilings and cornices, it is also used to precast and hold ornamental plasterwork.

Types of Plaster of Paris:

1. Gypsum plaster: Gypsum is a crystalline mineral composed of hydrated calcium sulfate (chemical formula ${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$). In addition to being colorless or white, gypsum is not soluble in water and is not at all hard. Gypsum and water can be poured together; the gypsum hardens as the water evaporates. The natural form of the gypsum is mineral bassanite. It is used for medical purposes, toys, fire-protected material, and laboratory. ${\mathrm{CaSO}}_4.\raisebox{1ex}{$1$}\!\left/ \!\raisebox{-1ex}{$2$}\right.{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)+\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2$}\right.{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\stackrel{∆}{\to }{\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)$
2. Clay plaster: It is the mixture of clay, sand, and water with the addition of plant fibers to enhance strength. It is used for home interiors.
3. Lime plaster: It is formed by the reaction of calcium hydroxide and sand that with carbon dioxide to transform into calcium carbonate. It is formed by the heating of calcium carbonate above $850°\mathrm{C}$ that results in calcium oxide. It is used in building materials. ${\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$
4. Cement plaster: It is made by a mixture of plaster, Portland cement, and water. It has some properties such as strength, hardness, quick setting time, and durability. It is used to make a smooth surface.