Boiling Point of assorted materials; condensation and evaporation

Keywords:
LOX LN2 liquid nitrogen oxygen gases balloons condensation evaporation sublimation boiling point gas laws expansion contraction Charles's Law change of state

Materials:
Liquid Nitrogen, ~1-2 L, in Dewar flask
Unsilvered Dewar Flasks (2)
Fire Extinguisher
assorted materials of contrasting b.p.

Hazards:
Cryogenic - Liquified gases, dry ice
Oxidizer - Liquid Oxygen
Fire - Liquid butane, acetone
Explosive - Liquid Oxygen (in presence of fuel)
Implosion - Glass Dewar Flasks
Electrical shock - hot plate
Burn - hot plate, Meker burner
other materials as determined

Preparation:
Arrange (as preferred, or) stage right, left to right:
• Meker or Fisher burner (use stage left, away from acetone bath)
• unsilvered Dewar to contain LN₂
• unsilvered Dewar to contain acetone/dry ice bath
• 1 L TF beaker to contain boiling water (hot plate)
• 1 L TF beaker to contain ice water

Provide 25mmX300mm test tubes fitted with 10-12" balloons containing:

purge air	b.p. K
helium	4.55
nitrogen	77
oxygen	90
carbon dioxide	195
butane	273
water	373


Procedure:
According to lecturer preference, or ...
place test tubes in baths in sequence to show that expansion, contraction, condensation, evaporation, or sublimation occurs according to temperature of bath and properties of material.
* In the case of water in balloon, heat sample vigorously using Meker burner to show that balloon will inflate if evaporation rate exceeds condensation rate. Caution - balloon will become very hot and if it bursts, the steam can cause injury. The use of a boiling chip is suggested. The use of standard protective equipment is suggested.

Disposal:
See EH&S instructions