Biodiesel Titration Using
Phenolphthalein or Turmeric

Biodiesel titration is a pretty short process. It usually takes between 10 and 15 minutes. The instructions may seem long, but are in fact just very detailed.


Instructions for Titration:

• Label your small cups 'Titration,' 'Isopropyl,' and 'Titration Solution' to avoid simple mistakes.

• Label the syringes with 'Biodiesel titration solution,' 'Isopropyl,' and 'Oil'.

• Pour some isopropyl, titration solution, and oil into the corresponding cups to avoid contamination.

• With the syringe measure 10 ml of isopropyl and put it in the 'titration' container.

• With the other syringe measure 1 ml of oil and add it to the 'titration' cup as well.

• Pick up the 'titration' cup up and use a swirling motion to mix it together.

• Put 3-4 drops of Phenolphthalein into the 'titration' cup and give it a swirl. (if using Turmeric, see ** below).

• Put 10 ml of titration solution in the appropriate syringe. You will not use the entirety of this - it will slowly be added until the pH indicator indicates it is enough.

• Add a drop at a time of the titration solution from the syringe into the 'titration' cup. Continue mixing it by swirling the cup and watch for it to change color. When the mixture turns pink and stays that way for 30 seconds, stop. (Phenolphthalein remains colorless until a pH of 8.3, at which point it turns pink.)

• Calculate how much titration solution was added by subtracting what is remaining from 10 ml that was previously in the syringe.

• Now perform titration two more times and average the results!


** If Using Turmeric as Your pH Indicator:

• Add enough turmeric to the titration cup to give it a pale yellow, then while adding the titration solution, wait till it turns a dark red and holds that color for 20 seconds. This indicates a pH of 8.4.

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