Molar Mass of an Unknown Liquid  

An empty flask and stopper is weighed in with a mass of 75.121 grams. To this flask 2 mL of an unknown liquid is added and then heated in a boiling water bath at 96°C. When all of the unknown liquid is vaporized the flask is removed from the bath and cooled. During the cooling the stopper is periodically opened just enough to let air in to equilibrate the internal and external pressures. During the experiment the laboratory barometer reads the pressure in the lab as 648 mm Hg. The flask is then weighed and found to have a mass of 76.036 grams. The volume of the flask is then measured and found to be 271.2 mL.     

1. What was the pressure of the vapor in the flask in atm?                                     _______________  

2. What was the temperature of the vapor in K?                                     _______________   

3. What was the volume of the flask in liters?                                      _______________       

4. How many moles of vapor are present?                                          _______________   

5. What was the mass of vapor that was present in the flask?             _______________   

6. What is the molar mass of the unknown liquid?                                _______________