Researcher

Jianbo Zhao

Objective

To determine the solubility of piperonal piperonal in pure n-haxane using density measurement. Volumetric flask size effect on percent error was also examined. assumption

Procedure


1. Set up all the equipments. Including temperature bath, tubes, balance and volumetric flasks
2. Take out 2 clean tubes [what kind? JCB] label them as A and B.
3. Started to measure the mass of Piperonal. With the calculation it would be around 3g
4. Put each tube with Piperonal. Add up pure n-Hexane into both tubes. Until 3 quarters of the whole tube, stop.
5. Put on the cabs and seal the tube really tight.
6. After that, use a tape to take the two tubes together. Tape them on on the edge of temperature bath which they can stick with each other. Set the temperature into 41C and put them in.
7. 60 minutes later, take both tubes out and transfer the supernatant into new clean tubes marked as A2 and B2.
8. Bath A2 and B2 with a beaker with 25C water about 10 minutes.
9. Weight clean different volume of flasks, pure in solution and start to measure the mass of whole weight.

Results

Measurements

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Pic.1 Measurment mass of piperonal in the tube.
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Pic.2 Seat both tubes and tape them into water bath at 40C.

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Pic.3 Two layers observed after 60 minutes bath at 40C.

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Pic.4 Put tubes into 10C water bath, crystal came out.

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Pic.5 Measure mass of solution in volume flasks.

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Pic.6 Finished measuring mass of solution in volume flasks.



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Plot 1: Measured Concentration via different volume of flasks

Discussion

  1. From this experiment, as the the volume of flasks decreases, the measured solution concentration increases. (From 0.08 M to 0.23 M). Since this happens for both samples it suggests that some type of systematic error is operating. This error is not inherent to this method since good agreement between 1, 2, 5 and 10 ml volumetric flasks was previously reported in EXP178.
  2. The range is roughly consistent with the previous report of the solubility of piperonal in hexane at 0.15 M (EXP071).

Conclusion

This experiment did not generate new measurements for the solubility of piperonal in hexane due to some type of systematic error where smaller volumetric flasks yield larger concentrations for the same solution. This will be investigated.[How? -AL]

Log

2010-10-19

11:32 Set water bath temperature to 40C
11:35 Calculate the mass of Piperonal about 3g.
11:57 Clean two tubes with pure n-Hexanes. Marked two tubes as A and B.
12:01 Weight empty tubes.
12:02 Pour about 3g Piperonal into tube. Weight both tube again. Take Picture.1
12:13 Add Hexane to both tubes about 3 quarters of the whole tube. Weight the tubes again.
12:16 Seal both tubes and stick tubes with tape into water bath. Take Picture.2
12:22 Put them in and start bath for 1 hour.
12:24 Measure mass of each of 2 10ml, 5ml, 2ml, 1ml flasks.
13:23 Take both tubes out, obserbed two layers of liquid. The temperature for water bath is 40C at that time.Take Picture.3
13:26 Put both tubes into a 25C water bath for 10 minutes. Take Picture.4
13:35 Take them out after 10 minutes bath and transfer the upper level liquid into two new tubes marked as A1 and A2. Observed most part of tube bottoms are solid.
13:40 Pour them into different volume of flasks and started to measure the mass of whole flask with capped on. Take Picture.5

2010-10-20

15:11 Clean the volume flasks used yesterday with pure Hexane and clean them with air.
15:27 Measured the empty flasks with caps on.
15:31 Put in the pure Hexane and weight the flasks with capped on. After measuring, take Picture.6