When titrating I use the zero based method (I think that is what it is called). Where you add a bit of your KOH and distilled water to your methoanol till you get a reaction, then you add your WVO.
My question is: Since I do that do I need to account for KOH purity on these "calculators"? It seems to me like it would be "considered" when you zero your test. If I don't need to indicate purity on these calculators do I just put it in at 100%?
Thanks,
Joe

You are thinking of two different things . The first is when you add the KOH to yuor alcohol before adding the oil . This is known as a blank titration . The purpose is to compensate for alcohol that has aged and beome acidic . The second is completly separate from the first and that is the question of purity . When discussing purity you always want to adjust your base amount to compensate for a purity lower than 100% , if you have 90% KOH you will want to adjust your base amount to 7.7 . As long as you are titrating with the same base you are going to use in your reaction you only need to adjust the base , not the titration .

quote:

As long as you are titrating with the same base you are going to use in your reaction you only need to adjust the base , not the titration .

I think this is just what he is after.

Total catalyst to use = titration + BaseAmount*(2-purity)

Right?

So titration of 5ml with a 90% pure base would be;

5 + 7*(2-0.9) = 12.7 g/L