Heptane Lab Report

Based on calculations #5 and #6 made above for solving the molecular weight, it was identified that the third unknown volatile liquid was Heptane: 100.20g/mol. Since the observed value was 104.8g/mol, it was assumed that Heptane was the only gas out of all that were listed that shared a similar value. Supported by table 2 and 3 the average molecular weight of acetone and the unknown volatile liquid was calculated to be approximately, 154.5g/mol and 104.8g/mol, respectively. The molecular weight (MW) for both acetone and the unknown volatile liquid was unsuccessfully proven to match the accepted values of 58.08g/mol and 100.20g/mol, respectively. More specifically, this was evident due to the percent error that was calculated, approximately

It is possible that the discrepancy of the molecular weight of both acetone and the unknown volatile liquid was caused by the deviation of mass in each trial. During the trial of the experiment aluminum foil was used as a cap for the Erlenmeyer flask and by using a pin, a hole was made into the cap to insure that the gas vapors would escape during the heating process, later the Erlenmeyer flask was measured after the heating process when the gas was fully condensed; however, this procedure effected the results collected. With the usage of the aluminum foil it had resulted the presence of excess moisture build up from the water bath which then had increased the mass of the gas that had been condensed due to it being measure with both the foil and elastic band. Since, the Erlenmeyer flask was left behind with the water moisture contained in the foil; therefore, it had affected the final mass of the condensed vapor inside the flask. Although the procedure was effective and adequate results were obtained, there are some improvements that can be made towards the experiment to make it exceptional. Instead of using the aluminum foil as the cap for the Erlenmeyer flask it would be suggested to use a rubber stopper that contains a pinhole, this way it would be much easier to dry the cap to

The steps that were taken involved using an analytical scale to weigh the Erlenmeyer flask containing no liquid in it (in grams) and filling the entire Erlenmeyer flask with water. Again, separately weighing its mass (in grams) and recording this value as the total mass/ final mass. Altogether, this gives the value of the mass of the liquid inside the flask because mass liquid = final mass – initial mass. Later, it was assumed that the density ratio of water is 1 gram = 1 mL. Using the density formula; density = mass(g)/volume(mL), rearranging would give the value of volume of the Erlenmeyer flask (in mL), simply by dividing the mass of liquid from the density of water. Altogether, this procedure was effective because the values for both flasks one and two were similar to one another in value, which makes sense because both were 50mL in size, as seen in calculation