DRAFT: This module has unpublished changes.

Discussion/Conclusion:


The purpose of this lab was to determine the molecular mass of a compound by measuring the freezing point depression. This was done by reacting lauric acid with an unknown solute. A pure solvent of lauric acid’s freezing point was first determined by melting and freezing it and then the solute was added and we observed the freezing point drop from 44.0 °C to 40.35 °C. This difference is the freezing point depression of the solute. From this freezing point change, the formula weight of the solute was calculated. The first trial with 0.5060 g of the solute produced a formula weight of 87.496 g/mol and the second trial with 1.0126 g of the solute produced a formula weight of 109.017 g/mol. Neither of these trials produced a formula weight similar to one of the compounds listed in the lab handout. These results were confirmed when a percent error of 28.52% in for the first trial and 10.9% in the second trial. We were able to determine this percent error because it was revealed that the actual solute was Benzoic Acid, which has a formula weight of 122.4 g/mol. In conclusion, the results of this lab were rather inaccurate because the identity of the unknown solute would have been determined solely by the formula weights. As in all labs, the possibility for human error is inevitable. One area where error may have occurred include not transferring all of the unknown solute from the weighing dish into the test tube or having the solute be stuck on the walls of the test tube. To improve this lab in the future, it would be crucial to stress the importance of transferring all of the solute into the test tube as well as increasing the number of trials in order to produce more precise and accurate results.

DRAFT: This module has unpublished changes.