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list of experiments
Solubility book (3rd Edn)
To determine the solubility of 2-naphthaldehyde, 4-hydroxybenzaldehyde, 4-nitrobenzaldehyde,
-vanillin and piperonal in methanol by UV-Vis spectroscopy using molar absorptivities (
obtained from NIST database.
Saturated solutions of 2-naphthaldehyde, 4-hydroxybenzaldehyde, 4-nitrobenzaldehyde,
-vanillin and piperonal in methanol were prepared in one dram vials and left to equilibrate for 24 hours. The supernatant from each solution was then decanted in to a different vail and subjected to dilutions until UV absorbance for them fell between 0.5-2.0 absorbance units. Using
ε values obtained from NIST database for each aldehyde, concentration of their saturated solution was calculated.
Saturated solutions -day2
[Where is the Spreadsheet with the calculations? JCB]
NIST UV spectral data
[NIST doesn't report the solvent so you'll have to look up the references to find out - also look on Beilstein for methanol and these solutes JCB]
11:00 Made-up saturated solution of 2-naphthaldehyde, 4-hydroxybenzaldehyde, 4-nitrobenzaldehyde,
-vanillin and piperonal in methanol. This was done by vortexing each of them for 10 min after it appeared like the solution had become saturated.
Solutions of piperonal and o-vanillin continued to become clear after vortexing, however once they were left undisturbed for 15-20 they started recrystallizing. Therefore they had to be revortexed, they formed clear solution again...after repeating this process 3 times..the clear solutions were left in the hood...soon after they started to recrystallize, with some supernatant in them..it is assumed that this supernatant solution is the saturated solution.
[Do you have any way to record ambient temperature (and its fluctuations) in the vicinity of your hood? Or any way to ensure that the solutions remain at a constant temperature? It seems to me that solubility data should always come with temperature anyway... -BH]
11:20 The solutions were left in the hood to equlibrate.
18:40 Obtained a picture of the solutions.
12:30 Centrifuged the vials for 1min, obtained a picture. [saturated solutions-day2]
12:40 Decanted the supernatant from the vials in to 5 new one dram vials labeled 1-5. Obtained a picture. [After decanting]
15:00 Performed dilutions of the saturated solution of 2-naphthaldehyde in methanol as described below
100uL 23A in a 10mL Volumetric flask
100uL 23A-1 in a 10mL Volumetric flask
100uL 23A-2 in a 10mL Volumetric flask
125uL 23A-2 in a 10mL Volumetric flask
150uL 23A-2 in a 10mL Volumetric flask
175uL 23A-2 in a 10mL Volumetric flask
200uL 23A-2 in a 10mL Volumetric flask
225uL 23A-2 in a 10mL Volumetric flask
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