Question

A white powder is used by doctors to support fractured bones.

(a) Write the name and chemical formula of the powder.

(b) How is this powder prepared?

(c) When this white powder is mixed with water, a hard solid mass is obtained.

Write a balanced chemical equation for the change.

Answer 1

Calcium Sulphate hemihydrate:

(a) Name and chemical formula of the powder.

1. The chemical name and formula of the white-coloured powder which is used by doctors for supporting fractured bones are known as Calcium sulphate hemihydrate.
2. The formula for Calcium sulphate hemihydrate – ${\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}$

(b) Preparation of powder.

1. The Calcium sulphate hemihydrate powder is prepared by mixing with water.
2. When this white powder is mixed with water a hard-solid mass is obtained.
3. Calcium sulphate hemihydrate is also known as plaster of paris.
4. This solid mass is known as calcium sulphate hemihydrate.
5. Gypsum is also a white powder known as calcium sulphate dihydrate which is formed from the calcium sulphate hemihydrate.

The chemical equation of the formation of gypsum from plaster of Paris:

1. ${\mathrm{CaSO}}_4.\frac{1}{2}{\mathrm{H}}_2\mathrm{O}+1\frac{1}{2}{\mathrm{H}}_2\mathrm{O}\to {\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$

The balanced chemical equation for the change is:

1. ${\mathrm{CaSo}}_{4.}\frac{1}{2}{\mathrm{H}}_2\mathrm{O}+\frac{3}{2}{\mathrm{H}}_2\mathrm{O}\to {\mathrm{CaSO}}_{4.}2{\mathrm{H}}_2\mathrm{O}$