Question

Molar Mass of a Vapor

Unknown liquid number: 1

Mass of flask + cap + rubber band: 74.00 g

Temperature of boiling water: 99.5^oC

Barometric pressure: 771 mm Hg

Mass of flask + rubber band + cap + condensed vapor: 74.38 g

Mass of condensed liquid: 0.38 g

Volume of flask: 146 mL

Molar mass of vapor: _____ 

Questions

1. If an insufficient amount of liquid unknown had been used, how would this have affected the value of the experimental molar mass?

2. What are the major sources of error in your determination of the molar mass?

3. If the flask was not thoroughly wiped dry, how would this affect the molar mass?

4. Isobutyl alcohol has a boiling point of 108 ^oC. How would you modify the procedure used in this experiment to determine its molar mass?