Question

How would each of the following procedural errors affect the results to be expected in this experiment? Give your reasoning in each case.

a. Not all of the liquid was vaporized when the flask was removed from the water bath.
b. The flask was not dried before the final weighing with the condensed vapor inside.
c. The flask was left open to the atmosphere while it was being cooled, and the stopper was inserted just before the final weighing.
d. The flask was stoppered and removed from the bath before

Answer 1

Procedural errors in vaporizing and weighing experiments, such as not fully vaporizing the liquid, not drying the flask, leaving the flask open, or stopping the process too soon, can lead to inaccurate mass measurements and erroneous results.

Step-by-step explanation:

Procedural errors in a laboratory experiment can significantly alter the expected results. In the context of an experiment where a liquid is vaporized in a flask, condensed, and then weighed, several specific errors can occur:

• Not fully vaporizing the liquid: If not all of the liquid is vaporized when the flask is removed from the water bath, the final mass measurement will include both the mass of the condensed vapor and the remaining unvaporized liquid leading to an inaccurate determination of the mass of the vapor alone.
• Non-dried flask: If the flask is not dried before the final weighing, any water remaining on the flask will add to the total mass, thus overestimating the mass of the condensed vapor and giving erroneous results.
• Flask exposed to the atmosphere: Leaving the flask open to the atmosphere while cooling can allow the vapor to escape or atmospheric moisture to enter the flask, impacting the accuracy of the mass measurement of the condensed vapor when the stopper is inserted just before weighing.
• Stopping the process too soon: Removing the flask from the heat before all the liquid has vaporized or before the system has equilibrated at ambient pressure could result in a lower vapor pressure, which may yield an incomplete conversion of liquid to gas and impact the mass measurement of the vapor.

Understanding how these procedural errors can affect the outcomes emphasizes the importance of precise laboratory techniques in yielding accurate experimental results.

Answer 2

Different procedural errors would affect the results of the experiment in different ways. Not all of the liquid vaporizing would result in an underestimation of the mass, not drying the flask would result in an overestimation of the mass, leaving the flask open would result in an underestimation of the mass, and stoppering the flask too early would result in an underestimation of the vapor pressure.

Step-by-step explanation:

a. If not all of the liquid was vaporized when the flask was removed from the water bath, the results of the experiment would be affected because the mass of the liquid that did not vaporize would not be included in the final measurement. This would lead to an underestimation of the mass of the substance being studied.

b. If the flask was not dried before the final weighing with the condensed vapor inside, the results would be affected because the weight of the water droplets on the inside of the flask would be included in the measurement. This would lead to an overestimation of the mass of the substance being studied.

c. If the flask was left open to the atmosphere while it was being cooled and the stopper was only inserted just before the final weighing, the results would be affected because the vapor inside the flask would have escaped and lost mass. This would lead to an underestimation of the mass of the substance being studied.

d. If the flask was stoppered and removed from the bath before all of the liquid had completely vaporized, the results would be affected because the vapor pressure inside the flask would decrease as the temperature decreases. This would lead to an underestimation of the vapor pressure and an overestimation of the boiling point of the substance being studied.