Molar Volume of Oxygen
|The Gas generated is collected by
displacement of water in the inverted 125 mL erlenmeyer flask.
The reaction system is kept intact until the reaction tube cools to allow for volume contraction upon cooling.
Note: the end of the gas inlet tube is kept in the gas bubble (not the water)!
If the volume of the gas bubble does not decrease as the the reaction cools, there is a leak in your system!
A. Before cooling
|Effect of Pressure on Volume||
B. After Cooling
|Since Volume of a gas varies inversely as the Pressure, to determine the
Molar Volume of oxygen, you will need to know, not only the VOLUME of the gas but
also its PRESSURE.
Getting the pressure of the gas in the flasks above can be done several ways.
1. Push the flask down (or pull it up) until the level of the water inside the flask is level with the level of the water on the outside.
At that point.......................................... Pinside = Patmospheric
2. Measure the height of the water inside the flask relative to that outside the flask. This difference in height of water levels represents a pressure difference! Convert this height differential from mm of water to mm of Hg (using the density of mercury). Then................. Pinside = Patmospheric - mm of Hg
In this experiment, you will use method 1.
A. Stopper the
flask tightly to prevent loss of water or Pressure.
Stoppering gas containing 125 mL
erlenmeyer flask at the original site for transport to the leveling tank.
Right.... Unstoppering the flask at the leveling tank.
Leveling the flask in the leveling
tank and placing a large rubber stopper over the mouth to prevent water from flowing in or
Right.... The flask after removing from the tank and drying the outside. The empty space above the water represents the volume of gas collected at atmospheric Pressure.
the cooled reaction tube, you also know the mass of
oxygen, O2, generated.
Some questions you might like to