Chemical Properties of Oxygen - With Metals

a) With sodium

Introduce a small piece of sodium metal into a jar of oxygen. It combines with oxygen to form sodium peroxide. Allow a piece of sodium to burn in a deflagrating spoon, and then introduce it into another jar of oxygen. It burns with a brilliant yellow flame to form sodium peroxide. Add some water into both the jars. Test these solutions with red litmus. It turns blue showing the formation of a basic oxide.

b) With calcium

Burn a piece of calcium metal in a deflagrating spoon, and introduce it into a jar of oxygen. It burns with a bright brick-red color, to give a white solid, calcium oxide or quick lime. Add some water to the jar. Shake well. Test with red litmus. It turns blue showing the formation of a basic oxide.

c) With magnesium

Burn a piece of magnesium and introduce it into a jar of oxygen. It burns with a dazzling white flame, to form magnesium oxide. A white deposit of magnesium oxide can be seen on the wall of the jar. (Fig.13.14)

d) With iron

Take very thin iron wire or iron wool and coil it around a matchstick. Light the matchstick and introduce it into a jar of oxygen. The iron will start burning with or without flame, but with a crackling sound, to form tri-iron tetroxide or magnetic oxide of iron. It is advisable to place a layer of sand in the jar, as the molten Fe₃O₄ may crack the jar.

e) With aluminium

Burn a thin aluminium wire, and introduce it in to a jar of oxygen. It burns with a dazzling white flame to form aluminium oxide.

f) With zinc, lead and copper

Metals like zinc, lead and copper also combine with oxygen, when heated, to form their respective oxides.

Burning of Compounds in Oxygen

a) Carbon monoxide

Carbon monoxide burns in oxygen, with a blue flame to form carbon dioxide (Fig.13.15). The resultant carbon dioxide turns a solution of lime water milky.

b) Ammonia

Ammonia burns in oxygen, with a greenish yellow flame to form water vapor and nitrogen.

c) Hydrocarbons

Hydrocarbons, such as methane, benzene, wax, etc. burn in oxygen to form water vapor and carbon dioxide.

Introduce a burning wax candle into a jar of oxygen. The candle will burn much more brightly (Fig.13.16). The inner side of the gas jar gets misty due to the deposition of tiny droplets of water. To check for carbon dioxide formation, add some lime water into the jar, after the candle is put off. Mix it well. The lime water turns milky.

Remember :

There are different types of waxes, having variable number of carbon and hydrogen atoms. So, it is represented by the formula C_xH_y.

---