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Solubility book (3rd Edn)
To determine the temperature at which different concentrations of 4-fluorobenzoic acid in ethanol solution will come out.
Five samples of solution were prepared with ethanol and acid. Five one-inch tall vials were filled with 0.4g ethanol each, then a known amount of acid was added to each vial to produce the desired concentration. First, each empty glass vial was weighed and the scale zeroed. Ethanol was then added to the vial until it weighed correctly. The exact weights are recorded in the results. After all five vials contained the solvent, the solute was added. We used wax paper to weigh specific amounts of 4-Benzoflouric acid and then scoop/pour into the appropriate marked vial. Now we have 5 marked vials containing different concentrations of acid and solvent. We covered the vials in parafilm and vortexed them for 30 seconds. We tagged the vials with manilla and placed them in a heated bath. Samples A1-A5 were dropped into a water bath heated to temperature 50 degrees and then lowered in increments to determine the temperature at which precipitate forms.
A1 was the only concentration sample to fully dissolve when heated, so since this could only possibly yield one data point, I would consider doing a similar experiment with lower molar concentrations closer to sample A1.
[Does this data point make sense with the results from EXP121? JCB] yes
We got sample A1 to come out of solution at -15 degrees. This was the lowest concentration sample and also the only solution to fully dissolve. We got one good data point from this experiment.
5:12-started weighing ethanol in vials
5:21-five vials filled with 0.4g ethanol
5:44-acid weighed into vials with ethanol
5:57-parafilmed and vortexed samples. A1 only sample fully dissolved.
6:10-tagged with manilla and placed in 30 degree bath with thermostat set to 50 degress
6:51-Bath reaches 50 degrees. A1 only sample fully dissolved.
6:55-Set thermostat for 25 degrees.
7:00-sample A1 forms precipitate at -15 degrees
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