We then added 10cm3 ethanoic anhydride to the salicylic acid and swirled the contents, this mixes together the two chemicals. We then added 5 drops of concentrated sulphuric acid to the flask and thoroughly swirled the mixture, this creates the solution that makes the aspirin. We then warmed the flask for 20 minutes in a 400cm3 beaker of hot water which was approximately 60°C, we made sure the flask did not go above 65°C because this could have caused the contents to evaporate. Part 2: Using a 25cm3 measuring cylinder we measured out 15cm3 of ethanol into a boiling tube and then prepared a beaker half filled with hot water at approx. 75°C, we got this temperature by filling the beaker with cold water and slowly adding boiling water from a kettle until we reached the right temperature.
Once 3-4 readings for the solution were collected, the 2M NaOH was added to the solution. The lid was quickly replaced in order to prevent heat from escaping and not being recorded by the temperature probe. The cup was swirled until the temperature reached a peak and began decreasing. After the 180s had passed, data collection ended. The solution was discarded into the waste bin, and the materials were washed.
The last step was the formation of Cu(s). This step recovered Solid elemental copper. Al(s) wire was placed in the solution from the last step and 5 drops of HCl along with a stir bar was added to the beaker and this was stirred on the hot plate. Cu(s) precipitate formed on the wire and the solution turned from clear to cloudy until it eventually become a brownish red color. When the reaction was complete the Al(s) wire was scraped with the stirring rod to get off any residual Copper product.
Sample Preparations Unknown water and reagent blanks are prepared in the same manner. 20 ml test tubes are taken and 5ml of water is pipetted into each of the test tubes. The pesticide standards are now inserted into the test tubes at concentrations of 0.1,0.2,1,2,5,10 and 30 ng/ml-1. The mixtures are mixed and kept in equilibrium for 30 minutes. After the 30 minutes is done, the tests tubes are then immersed in a 100 degrees Celsius methanol water bath for 15 minutes.
Straight afterwards, saline solution was added (NaCl 0.16 M, pH=7) to the 10ml of the yolk solution with a Pasteur pipette, avoiding the sample diffusion, forming two phases and filling the tube completely. The ultracentrifugation was carried out during 19.5 h at 4ºC and 45000 rpm. (244.500 x g) in a Kontron Centrikon T-2190 ultracentrifuge in a TFT 50.38 rotor,
Throughout the mixing process, the clear red solution slowly changes to a denser red solution (Appendix figure 23). A thermometer was used for temperature checking. The beaker was removed from the hot plate when the temperature was found to be higher than 50 ℃. This was done to prevent a sudden gelation happen before all the active dissolved in the ethylene glycol. Moderate heating of the solution for a period of time is allowed to obtain a wet gel (Appendix figure 24).
The acid was poured into the flask until there was a permanent pink colour. The acid was allowed to be poured for a little longer before the flask was removed and taken to a lab bench with a buret that contained 0.1 M sodium hydroxide, and the amount of acid used was recorded. The sodium hydroxide was added into the flask in small amounts
It was then washed off with ether after the drying process was finished and allowed 5-10 minutes for the drying of the ether solution. ?M HCl was added drop wise to tube 2 to neutralization, while testing the solution with litmus paper. A boiling stick was then added to the tube and heated cautiously to bring most of the solid carboxylic acid into solution. The tube was then allowed to cool slowly to room temperature then cooled in ice. The solvent was removed and the residue recrystallized from boiling water.
A stir bar was also added to the solution. The glass stirring rod from previous steps was used to remove pieces of Cu that formed on the Al wire, so that more Al surface would be exposed. A steam bath was prepared with 50 mL of deionized water, the glass rod was used to remove as much copper from the aluminum wire as possible, and the Al wire was then disposed of in the solid waste container. The mass of an evaporating dish was recorded, and the Cu was transferred on to the evaporating dish. Water was removed from the dish, and the Cu was then washed thrice with 5 mL deionized water, and decanted between washings.
On the second day of incubation, the plate was removed from the incubator and placed over a hot plate heating Iodine solids. The smoke of the Iodine stained the plate to display the presence or absence of a halo around the bacteria 2.12 Lipid Hydrolysis This test was done by making a single line streak inoculation on a tributyrin agar plate and allowing incubation. After the incubation period, the plate was observed for the presence or absence of a halo around the bacteria. 2.13 Gelatin Liquefaction A gelatin deep was deep stabbed and incubated. After incubation the tubes were placed in 4ºC for 30 minutes.