In the molecular weight determination experiment, what would be the effect if some air remains in the flask after the compound was completely vaporized?
The molecular weight of the compound would be some kind of a weighted average between the compound and the air that was left.
Not certain of your procedure, however if you were measuring volume, and air were incuded, then your moles calcuated would be too high, and so the mol mass too low.
If some air remains in the flask after the compound is completely vaporized in a molecular weight determination experiment, it can have several effects:
1. Incorrect data: The presence of air in the flask can lead to a higher apparent molecular weight of the compound. This is because the air molecules will contribute to the overall weight measurement, resulting in an overestimation of the compound's molecular weight.
2. Contamination: Air can contain impurities, such as dust particles or other gases, which can contaminate the vapors of the compound. This contamination can affect the accuracy of the molecular weight determination.
3. Incomplete vaporization: Air can prevent complete vaporization of the compound by occupying some of the space in the flask. This can lead to a lower yield of the compound and affect the overall accuracy of the experiment.
To avoid these effects, it is crucial to ensure that the flask is properly evacuated or purged of air before conducting the molecular weight determination. This can be achieved by several methods, such as using a vacuum pump or purging the flask with an inert gas (e.g., nitrogen).
To mitigate the risk of incomplete vaporization, it is important to ensure that the compound is heated sufficiently and that any remaining air in the flask is allowed to escape before sealing the system. Using a heating method that allows gentle heating of the flask, such as a water bath or oil bath, can help minimize the presence of air and ensure complete vaporization.