Physical Properties of Oxygen

• Color-odor-Taste

Oxygen is colorless, odorless and a tasteless gas.

• Density

It is slightly denser than air.

Vapor Density of oxygen = 16 (Vapor density of air = 14.4)

Experiment to show that oxygen is denser than air

Take two gas jars, 'A' containing oxygen and 'B' containing air. Invert jar A over jar B. Oxygen being heavier than air, displaces air from jar B. This can be confirmed by introducing a glowing splinter in the gas jar (Fig.13.8). The splinter burns brightly showing a high presence of oxygen.

• Solubility in water

Oxygen is only slightly soluble in water. 100 volumes of water dissolve 4 volumes of oxygen at STP (Standard temperature and Pressure). As the temperature increases, the solubility of this gas gradually decreases. Although the solubility of oxygen in water is only 4% at STP, it is enough for fish and other aquatic animals and plants to breathe.

Remember :

STP = Standard temperature and pressure.

Temperature = 0^oC

Pressure = 76 cm or 760 mm of mercury.

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Experiment to show solubility of oxygen in water

Take distilled water in a trough. Boiled and cooled water can also be taken since it does not contain dissolved air. Invert a gas jar filled with oxygen, over it, as shown in the figure (Fig.13.9). After some time, the level of the water rises inside the gas jar indicating that the water in the gas jar has absorbed a part of oxygen.

Liquefaction and solidification

Under 1 atmospheric pressure, oxygen condenses to a pale blue liquid, at -183^oC. When cooled to -218^oC, it freezes to a snow like solid.

Remember :

Both liquid and solid oxygen are paramagnetic substances. This means they posses a small positive magnetic affinity for a magnetic field.

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