Molecular Weight Determination of Butane Gas

1
Molecular Weight Determination of Butane Gas
General Chemistry 101/102Laboratory
ManualUniversity of North Carolina at Wilmington
2
MW Determination of Butane Gas

• Purpose

• Determine the molecular weight (molar mass) of a
  gas from information about its mass, volume,
  temperature, and pressure.
• Demonstrate applications of the Ideal Gas Law and
  Daltons Law of Partial Pressures.

• Safety Considerations
• Butane gas is very flammable. There should be no
  open flames in the laboratory during this
  experiment.

3
MW Determination of Butane Gas

• Procedure
• Fill a baby bottle with water to the very top.
• Cover the bottle with a glass plate.
• Invert the bottle in a pneumatic trough and
  carefully remove the glass plate.

4
MW Determination of Butane Gas

• Procedure
• Insert the tube from the butane canister under
  the lip of the inverted baby bottle.
• Release approximately 200 mL of gas into the
  bottle by pressing straight down on the valve.
  Do not displace all of the water from the bottle.

5
MW Determination of Butane Gas

• Procedure
• Raise and/or lower the baby bottle until the
  water level in the bottle is even with the water
  level in the trough, then read the volume of the
  gas from the graduations on the bottle.

Water level in bottle lined up with water level
in trough
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MW Determination of Butane Gas

• Formulas and Equations

g R T
M
P V
P
butane