The table below shows the properties and uses of oxygen and carbon dioxide in the air. Gas Properties
Oxygen zƒ Colourless, odourless, tasteless
ƒz ƒz ƒz ƒz
Only slightly soluble in water Slightly more dense than air Supports combustion
Reacts with many elements to form oxides
Carbon dioxide
ƒz
ƒz ƒz ƒz
Colourless, odourless, tasteless
Only slightly soluble in water Slightly more dense than air Does not support combustion
Uses ƒz ƒz ƒz
ƒz ƒz ƒz ƒz ƒz ƒz ƒz ƒz ƒz
Respiration Combustion
Medicine (ventilation and resuscitation)
Diving and mountain climbing gear Welding and cutting metals Steel manufacture Launching rockets Photosynthesis Fire extinguishers
Refrigeration and food packaging Carbonation (fizzy drinks) Special effects (dry ice)
Test ƒz ƒz
Relights a glowing splint No effect on litmus
22.4
ƒz ƒz
Changes limewater from colourless to milky
Dissolves in water to form carbonic acid, which turns blue litmus red
z Fig. 22.4.3
An oxygen tank used for diving
Learn more about testing for oxygen in Chemical World 12.5
a F Nitrogen is such Testing for gases
Using the information in the table above, plan, design, carry out and write up an investigation to test for the presence of oxygen, carbon dioxide and hydrogen in the air.
an unreactive gas that food- packaging companies often remove the air surrounding their product and replace it with nitrogen. The gas in a bag of crisps is actually nitrogen gas.
