Dumas Method Experiment:
In this experiment, we measured a flask with an aluminum foiland elastic band set up then added 4mL of methanol inside the flaskand sealed with the foil covering and boiled in a water bath untilall the liquid vaporized (this will drive out any air in the flaskand push out all excess vapour). Then we cooled it to let thevapour condense and reweighed the flask with the vapour in it. Thefollowing questions pertain to the experiment:
For each of the following experimental conditions determinewhether the calculated value for molar mass would be: A) too high B) Too low C) Unaffected. In eachcase, explain how this result occurs.
a) After removing he flask from the water bath, the experimentercools the flask to room temperature but does not dry it. Thecalculated molar mass will be: A) too high B) Too low C)Unaffected. Explain.
b) The flask is removed from the water bath containing vapouronly, the experimenter cools the flask to room temperature and somevapour condenses inside the flask. The calculated molar mass willbe:Â Â A) too high B) Too low C) Unaffected. Explain.
c) The flask volume is not measured; instead the experimenterassumes the flask volume to be exactly 125.0 mL. The calculatedmolar mass will be:Â Â A) too high B) Too low C)Unaffected. Explain.
d) From the time the mass of the unused flask assembly (flask,foil and elastic band) is recorded the flask is handled severaltimes with oily fingers. The calculated molar mass will be A) toohigh B) Too low C) Unaffected. Explain.
