# 10.21 Describe the importance of the following : (i) limestone (ii) cement (iii) plaster of paris.

(i) Limestone-

The chemical formula is $CaCO_{3}$

Importance of limstone is-

• It is used as a building material in the form of marble and in the manufacture of quick lime
• Calcium carbonate along with magnesium carbonate is used as a flux in the extraction of metals such as iron.
• It is also used as an antacid, mild abrasive in tooth paste, a constituent of chewing gum, and a filler in cosmetics.

(ii) Cement-

Cement is an important building material. It is amixture of triclcium silicate($Ca_{3}SiO_{5}$) and tricalium aluminate($Ca_{3}Al_{2}O_{6}$).

Importance of cement-

It is used in concrete and reinforced concrete, in plastering and in the construction of bridges, dams and buildings

(iii) Plaster of Paris-

It is a hemihydrate of calcium sulphate. It is obtained when gypsum, $CaSO_{4}.2H_{2}O$, is heated to 393 K.

Importance of POP-

It is used in medicine as surgical bandages and also it is used for making casts and moulds.

Exams
Articles
Questions