Question

SIMPLE DISTILLATION (3) Name Unknown Number GRADES: unknown Report 1. Complete the table for the distillation of2-propano.(4pts Volume (mL) 0 3 6 9 12 15 18 21 Residue Temperature (°C) |toke last!36 3s le- tst 2. Complete the table for the distillation of the unknown. (4pts) Volume (mL) 0 3 9 12 15 18 21 Residue 6 (ml) 142 l sve emperature (C) 15se. | 00. 18p"clag't 3. A student in an organic chemistry laboratory starts a distillation. After a few minutes of heating the flask, the student realizes that there are no boileezers in the flask. Rather than add the boileezers to the hot liquid, the student allows the liquid to cool for a few minutes, then adds the boileezers. Explain why this is the correct procedure. (2pts) The water must enter the condenser jacket at the lower end and exit at the upper end ra the reverse directions. Why? (3pts) 4. 17

Answer 1

3. Boileezers are used to provide nucleation sites and thus help in efficient heating of the solvent preventing violent heating or even explosion. However if we add them when the solvent is still hot, then this may lead to the solvent to boil violently due to the sudden appearance of nucleation sites and thus causing a heat burst or even an explosion. So it is always advisable to first cool the solvent before adding the boileezers.

4. If water is flowed from top to bottom, then water will not be present in the chamber for sufficient portion of time to extract the heat. This would lead to inefficient cooling of the distillation chamber which is our primary goal. In addition to that overheating may even cause the glassware to get cracked.