Calcium Carbonate Limestone Or Marble

Preparation

(i) From slaked lime: It is prepared by passing equimolar amount of carbon dioxide through slaked lime.

Ca(OH)₂ + CO₂ CaCO₃↓ + H₂O

(ii) From calcium chloride: It is prepared by adding an aqueous solution of sodium carbonate to calcium chloride.

Na₂CO₃ + CaCl₂ CaCO₃↓ + 2NaCl

Properties

(i) It is a white fluffy powder almost insoluble in water.

(ii) When heated to 1270 K, it decomposes to form quick lime.

CaCO₃ CaO + CO₂

(iii) It reacts with dilute acids evolving CO₂ gas.

CaCO₃ + 2HCl CaCl₂ + H₂O + CO₂

CaCO₃ + H₂SO₄ CaSO₄ + H₂O + CO₂

Uses

(i) Calcium carbonate is used as a building material in form of marble.

(ii) It is also used as a raw material for the manufacture of sodium carbonate by Solvay−ammonia process.

(iii) In pure and finely powdered form, it is used in tooth paste and cosmetics.

(iv) It is used in agriculture for neutralizing the acidity of soil.