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)
a) The calculated molar mass will be B) too low. This occurs because when the flask is not dried after cooling, there may be residual water droplets present on the surface of the flask. These water droplets contribute to the mass and therefore decrease the measured mass of the substance inside the flask, leading to a lower calculated molar mass.
b) The calculated molar mass will be C) unaffected. In this case, some vapor condenses inside the flask while it is being cooled. However, because the condensation occurs inside the flask and is accounted for in the measured mass of the substance, it does not affect the calculated molar mass.
c) The calculated molar mass will be B) too low. When the flask volume is assumed to be exactly 125.00 mL instead of measuring it accurately, any deviation or inaccuracy in the actual volume will affect the calculated molar mass. If the actual flask volume is larger than 125.00 mL, the calculated molar mass will be lower than the true value.
d) The calculated molar mass will be A) too high. When the flask is handled with oily fingers, it may leave a thin layer of oil on the surface of the flask. This oil adds to the measured mass of the flask assembly, leading to an overestimation of the mass of the substance inside the flask and thus a higher calculated molar mass.
a) In this case, the calculated molar mass would be too high (A). The reason for this is that when the flask is not dried after being cooled to room temperature, there might be residual water on its surface. This water will contribute to the mass of the flask, and when calculating the molar mass, this extra mass will be included, leading to an overestimate of the molar mass.
b) In this scenario, the calculated molar mass would be too low (B). When some vapor condenses inside the flask during the cooling process, the mass of the condensed vapor is not taken into account. As a result, the measured mass of the substance inside the flask will be lower than the actual mass, leading to an underestimate of the molar mass.
c) The calculated molar mass will be unaffected (C) in this case. Assuming the flask volume to be exactly 125.00 mL does not directly impact the mass measurement. The molar mass is determined from the mass of the substance and the volume is not involved in the calculation. However, it is worth noting that if the assumption of the flask volume is significantly different from the actual volume, it may introduce inaccuracies in subsequent calculations.
d) The calculated molar mass would be unaffected (C) in this situation. The handling of the flask with oily fingers does not directly impact the mass measurement. As long as the mass of the unused flask assembly was accurately recorded, the oily residue on the outside of the flask will not affect the determination of the molar mass. However, it is generally good practice to handle laboratory equipment with clean hands to minimize any potential contamination.