Advance Study Assignment: Molar Mass of a Volatile Liquid 1, A student weighs an empty flask and stopper and finds the mass to be 54.868 g. She then adds about 5 mL of an unknown liquid and heats the flask in a boiling water bath at 100C. After all the liquid is vapor- ized, she removes the flask from the bath, stoppers it, and lets it cool. After it is cool, she momentarily removes the stopper, then replaces it and weighs the flask and condensed vapor, obtaining a mass of 55.802 g. The volume of the flask is known that day is 747 mm Hg. be 242.5 mL. The barometric pressure in the laboratory What was the pressure of the vapor in the flask in atm? a. P = atm b. What was the temperature of the vapor in K? the volume of the flask in liters? T = K V = c. What was the mass of vapor that was present in the flask? grams d. How many moles of vapor are present? moles e. What is the mass of one mole of vapor (Eq. 2)? MM = g/mole How would each of the following procedural errors affect the results to be expected in this experiment? Give your reasoning in each case. 2. a. All of the liquid was not vaporized when the flask was removed from the water bath. b. The student read the barometric pressure as 727 mm Hg rather than its true value of 747 mm Hg. c. The flask was left open to the atmosphere while it was being cooled, and the stopper was inserted just before the final weighing. d. The flask was removed from the bath before the vapor had reached the temperature of the boiling water. All the liquid had vaporized.