Dumas Method Experiment: In this experiment, we measured a flask with an aluminu

Question

Dumas Method Experiment:

In this experiment, we measured a flask with an aluminum foil and elastic band set up then added 4mL of methanol inside the flask and sealed with the foil covering and boiled in a water bath until all the liquid vaporized (this will drive out any air in the flask and push out all excess vapour). Then we cooled it to let the vapour condense and reweighed the flask with the vapour in it. The following questions pertain to the experiment:

For each of the following experimental conditions determine whether the calculated value for molar mass would be: A) too high B) Too low C) Unaffected. In each case, explain how this result occurs.

a) After removing he flask from the water bath, the experimenter cools the flask to room temperature but does not dry it. The calculated molar mass will be: A) too high B) Too low C) Unaffected. Explain.

b) The flask is removed from the water bath containing vapour only, the experimenter cools the flask to room temperature and some vapour condenses inside the flask. The calculated molar mass will be:  A) too high B) Too low C) Unaffected. Explain.

c) The flask volume is not measured; instead the experimenter assumes the flask volume to be exactly 125.0 mL. The calculated molar mass will be:  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 several times with oily fingers. The calculated molar mass will be A) too high B) Too low C) Unaffected. Explain.

Explanation / Answer

Dumas Method Experiment: In this experiment, we measured a flask with an aluminu

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