Titrations-Not as hard as I thought.

Been a while since I posted anything. I am doing a whorkshop for High School teachers this summer so I thought I'd run a few experiments they will perform. We will titrate some WVO, make B100 and determine it's viscosity. So today I let my 9 year girl and 7 year old boy help do the titrations. I had read the ASTM procedure for a titration and was a little intimidated but after thinking about it I saw where it could be made a lot easier. I made a 1g NaOH/L isopropanol (IPA) solution the day before. We added 25 mL of IPA to a 125 mL flask with a stir bar and then added 3 drops of phenolphthalein indicator . We titrated to a faint pink lasting for about 20-30 seconds. So the solvent takes about 0.5 to 0.8 mL of base. We then add 1mL of waste oil from the Dixie Classic Fair (Dave gave me some a while back). We recorded the starting volume and then titrated to the faint pink again. We recorded the ending volume and subtracted to find the amount of solution used. After four duplicate runs we averaged 2.47 +/- 0.03 mL. This translates to using an extra 2.47 g of NaOH per liter of oil. So this oil would need 3.5 + 2.47 = 5.97 g NaOH/liter oil. A rough calculation tells me this is oil is about 15% FFA. Definitly not a hard test to do. I wonder why it took me so long to try it???? Kids loved seeing the color change, of course.