Liquid/Liquid Extraction

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Titration Methodology

The following procedure is recommende for determining the concentration of acetone in the effluent stream.

Procedure

1. Pour 300 ml of hydroxylamine hydrochloride solution into a beaker.
2. Put a magnetic stirrer into the beaker and place onto a stirring plate and turn on the stirring plate.
3. Put the pH meter into the beaker into the solution and turn it on.
4. Record the initial pH.
5. Note the initial height of NaOH in the burette.
6. With a syringe, add 1cm³ of the sample into the hydroxylamine hydrochloride solution. The pH of the solution will then begin to decrease.
7. Titrate this with the NaOH solution provided. Bring the pH back to its initial pH (recorded in 4).
8. Note the final NaOH level on the buret. Subtract this value from the initial NaOH level to find the volume of NaOH needed to titrate the sample.
9. The volume percent of acetone is equal to this NaOH volume multiplied by 0.78.(Why?)

Notes

• After one titration has been completed, you can add another 300 ml of hydroxylamine hydrochloride solution directly into the beaker and perform another titration on top of the titration that has just been conducted.
• After the beaker has been filled up, put the waste into the red gasoline canisters located to the left of the fume hood.
• Unless another titration is to be conducted immediately, place the pH meter into the bottle of distilled water provided. The pH meter can be damaged if it is left in open air for extended periods of time.
• The results of this titration give volume fraction, and not mole fraction!  Ideally, they should be the same, but be sure to include a justification of the usage of the volume fraction in the reports.
• When finished, rinse the syringe with distilled water.
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