Behavior of Gases: Molar Mass of a Vapor

Name:

Title: Behavior of Gases: Molar Mass of a Vapor

Purpose: To observe how changes in temperate and pressure affect the volume of a fixed amount of a gas; to determine the molar mass of a gas from a knowledge of its weight, temperature, pressure, and volume.

Procedure Modification: We were assigned unknown A. A Bunsen burner was set up for the experiment. A piece of aluminum foil was placed over the mouth of the flask. A small hole was made at the center of the foil. The weight of the flask and cap was recorded. The foil was removed to place 2 mL of the unknown liquid in the flask and then covered back with the foil. The flask was then clamped at the neck and immerse in 600 mL beaker filled with water attached to the Bunsen burner. About two or three boiling chips were added to the water. During the experiment, I observed the amount of time it took to shock a substance with heat to make it boil and to make sure that it is completely evaporated. Once the water began to boil its temperature was recorded by a calibrated thermometer, the barometric pressure was recorded as well. We applied the thermometer calibration curve to the temperature recorded. As soon as all of liquid was vaporized from the flask we removed it from the boiling water and set it aside to cool. Once cooled (room temperature), the flask was wipe dry of any water or excess liquid. Finally, the flask, foil and condense liquid were all weighed and the weight was recorded.

Observations: One major error in the experiment was the equipment necessary for part A of the lab that was not available for this lab. Instead of a 600 mL beaker, our group had to use a bigger one because all of the other beakers were taken. There were no smells during this experiment.

Results: Molar Mass of a Vapor-

1. Unknown liquid number ____________________

2. Wt. of flask + cap + rubber band ____________________ g

3. Temperature of boiling water ____________________ ⁰C

Correction ____________________⁰C

Corrected temperature ____________________⁰C

4. Barometric pressure ____________________mm Hg

5. Wt. of flask + rubber band + cap + condensed vapor ____________________ g

6. Wt. of condensed liquid ____________________ g

7. Volume of flask ____________________ mL

8. Molar mass of vapor ____________________ g/mole

Conclusions: We can conclude this method of vaporization is sufficient when trying to determine the affect a change in pressure and