For each of the following experimental conditions determine whether molar mass would be:
1) too high, B) too low or C) unaffected. In each case, /explain/ how this result occurs
a) after removing the 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) B) C)
b) the flask is removed form the water bath containing vapor only, the experimenter cools the flask to room temperature and some vapour condenses inside the flask. The calculated molar mass will be: A) B) C)
c) the flask volume is not measured; instead the experimenter assumes the flask volume to be exactly 125.00mL. The calculated molar mass will be: A) B) C)
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) B) C)
Details? What are you doing? How?
This is just a question on my chem lab which is determining the molar mass of a volatile liquid. i don't understand how to answer this question, esp with the reasoning that has to be provided. help for this would greatly be appreciated!
a) The molar mass will be too low. This is because when the experimenter cools the flask to room temperature but does not dry it, any residual water molecules present on the surface of the flask will contribute to the overall mass of the flask. These extra water molecules will increase the measured mass of the flask, leading to a lower calculated molar mass.
b) The molar mass will be unaffected. When some vapor condenses inside the flask, the mass of the condensed vapor molecules will be accounted for in the measured mass of the flask. Since the molar mass is calculated based on the measured mass of the flask, the presence of condensed vapor will not affect the calculated molar mass.
c) The molar mass will be too high. Assuming the flask volume to be exactly 125.00 mL introduces a systematic error in the measurement. If the actual volume of the flask is smaller than assumed, the calculated molar mass will be higher because the measured mass will be divided by a smaller volume, resulting in a larger molar mass.
d) The molar mass will be too high. When the flask is handled several times with oily fingers, some additional mass from the oils will be transferred to the flask. This extra mass will increase the measured mass of the flask, leading to a higher calculated molar mass.