C ARBON D IOXIDE Icy Chan F.3D (2)

H ISTORY OF CARBON DIOXIDE. The Flemish chemist Jan Baptist van Helmont Scottish physician Joseph Black.

Carbon dioxide (chemical formula CO 2 ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom.

Molar mass: (14) g/mol Molecular shape: linear Test the presence of carbon dioxide: turn limewater from colourless to milky Other names: Carbonic acid gas; carbonic anhydride; dry ice

Carbon dioxide pressure-temperature phase diagram showing the triple point and critical point of carbon dioxide.

Chemical Properties  slightly acidic  potential hazards: nil  It is very stable gas at ordinary temperature and pressure.  Reaction with water: Carbon dioxide dissolves in water only to a very small extent. This small quantity of the gas combines with the water to form carbonic acid.  Action with basic oxides: Carbon dioxide reacts with basic oxides such as potassium oxide, sodium oxide and calcium oxide to form carbonates.  Action with alkalis: Carbon dioxide is readily absorbed by alkalis such as sodium hydroxide and potassium hydroxide, to form their respective carbonates.

laboratory preperation:  In the laboratory, carbon dioxide is usually prepared by the action of dilute hydrochloric acid on marble chips. Marble chips are taken in a round-bottomed flask, as shown in figure  Dilute hydrochloric acid is added through the thistle funnel. The gas can be collected by the upward displacement of air.

U SES OF CARBON DIOXIDE Food Beverages Wine making Lasers Fire extinguisher Oil recovery RefrigerantpH control