Gas Behavior

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Page ID: 131395

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Required Training	Required PPE
UC Lab Safety Fundamentals	Lab coat, safety glasses/goggles, nitrile gloves

Equipment	Chemicals
2 Balloons	Liquid N₂
One filled with He
One filled with O2
2 Low profile Dewar

Procedure:

1. Fill one balloon with helium, another with air

a. Attach a weight to the helium balloon so it doesn’t float away.

2. Each balloon is inserted into dewars filled with liquid nitrogen

3. The helium balloon will shrink to a fraction of its original size

4. The oxygen balloon with shrink much more than the helium balloon

Discussion:

Charles’ Law predicts a fourfold decrease in the volume of a gas as it is chilled from room temperature, 20 degrees Celsius, to liquid nitrogen temperature, -196 degrees Celsius. If the gas in the balloon condenses, as oxygen does at -183 C, the volume change is much greater. The density of liquid oxygen at -183 C is 1.149 g/mL, and that of the gas at 0 C is 1.429 g/L. Therefore, the volume of the balloon can shrink by a factor of more than 700.

Hazards:

Liquid nitrogen is a cryogenic hazard; caution must be used when handling. In case of accidental freezing of body parts, remove any clothing that may restrict circulation to frozen area. Do not rub frozen parts as tissue damage may result. As soon as practical, place the affected area in a warm water bath which has a temperature not to exceed 105°F (40°C). Never use dry heat. Call a physician as soon as possible.

Frozen tissue is painless and appears waxy with a possible yellow color. It will become swollen, painful, and prone to infection when thawed. If the frozen part of the body has been thawed, cover the area with dry sterile dressing with a large bulky protective covering, pending medical care. In case of massive exposure, remove clothing while showering with warm water. Call a physician

SOP:

N/A

Disposal (by Storeroom)

N/A