I've run into problems with measuring lye myself, and ultimately managed to work out a loose but somewhat workable way to measure out the lye by volume. It produced some of my best results to date, too, so I think I'm safe to share it with yas.
Sodium Hydroxide has a density of 2.1 grams per cubic centimeter. Since a cubic centimeter = a milliliter, you can use your beaker with mL scale on it to measure out the lye volumetrically. For a test batch with virgin oil it's going to be some incredibly small number; under 2ml, I believe. I was only doing a 300mL test batch, so I needed under a milliliter of NaOH.
Using the density of NaOH, convert your titrated grams into milliliters, then measure them out volumetrically and add to your methanol as per normal. I'd suggest erring on the side of caution when measuring it out though; unless your beaker is graduated in .01mL increments it might be hard to get a truly accurate volume.
I decided when I tried it to err on the low side, as an incomplete reaction I've read can be reprocessed but too much lye is worse news on the washing step.
In the end though, all these guys on the list are right; there's no substitute for a good, accurate gram scale. Just picked on up myself, in fact, measures out to .1 grams with a 500g capacity.
Good luck to ya!
-K
On 10/15/05, Brian Rodgers <[EMAIL PROTECTED]> wrote:
Hi biodieselers
I am here with my wife in our kitchen working on our first titration of WVO.
We have determined through heating a sample of WVO that no water is
present. We have found a soil test kit that has several types of
litmus paper. We did several tests of the litmus to determine if it
was still fairly accurate by testing a light solution of lye water,
household water, distilled water and finally battery acid. We have
compared the litmus paper color change and are satisfied that we can
tell the difference in major pH scales. By the way, this
experimentation is too much fun.
We have several browser windows open to the archives and conversion
tables for reference. It seems the first thing I forgot to collect for
this first test is a gram scale. We live 15 miles from town and a
hopeful there is a way to measure the lye without making a special
trip. Or, are we done for the day?
We have a decent thermometer, 1 beaker with ml scale, two syringes
with cc scales, goggles, gloves and lots of excitement.
Our question is this: Can we do this first step without the scale?
What else are we forgetting if a trip to town is needed?
Thanks for your help.
Brian & Nell Rodgers
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