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Re: What exactly is titration?
The following is from journeytoforever.org The REASON for titrations is to find out exactly how much LYE you need to correctly transesterify the glycerin from the oil. Too much and you get jelly. Not enough, and you will have an incomplete reaction.
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Basic titration
An electronic pH meter is best, but you can also use pH test strips (or litmus paper), or phenolphthalein solution (from a chemicals supplier).
Dissolve 1 gram of lye in 1 liter of distilled or de-ionized water (0.1% lye solution).
In a smaller beaker, dissolve 1 ml of dewatered WVO oil in 10 ml of pure isopropyl alcohol. Warm the beaker gently by standing it in some hot water, stir until all the oil dissolves in the alcohol and the mixture turns clear. Add 2 drops of phenolphthalein solution.
Using a graduated syringe, add 0.1% lye solution drop by drop to the oil-alcohol-phenolphthalein solution, stirring all the time, until the solution stays pink (actually magenta) for 10 seconds.
Take the number of milliliters of 0.1% lye solution you used and add 3.5. This is the number of grams of lye you'll need per liter of oil.
With a pH meter or test strips, use the same procedure without adding the phenolphthalein. Add the 0.1% lye solution drop by drop as before until the pH reaches 8.5.
Better titration
Unless you have a very accurate scale, it's not easy to measure exactly 1 gram of sodium hydroxide. It's much easier to measure 5 gm than 1 gm, so mix 5 gm of sodium hydroxide with 500 milliliters of distilled or de-ionized water.
Before titration measure out 5 ml of the stock solution, add 45 ml of distilled or de-ionized water. This makes a 0.1% lye solution.
It's also not easy to measure exactly 1 milliliter of oil. Instead of the usual 1 ml of oil and 10 ml of isopropyl alcohol, mix 4 ml of oil in 40 ml of isopropyl alcohol in a glass beaker.
Warm the mixture gently by standing the beaker in hot water, stir until all the oil disperses and it becomes a clear mixture.
Then titrate as usual, measuring milliliters of stock solution used. When it reaches pH8.5 count up the number of milliliters used as normal and divide by 4. This will give a much more precise measurement.
To save on isopropyl alcohol, use 2 ml of oil in 20 ml of isopropyl and divide the results by two -- still twice as accurate.
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