The end point of a titration should not come as a surprise to the analayst .Before a single drop of titrant has been added ,a n estimate of the end point volume should be carried out .For a simple foreward titration ,the approximate titre is given by
sample weight
--------------------- = "x" ml ( titre volume)
equivalent weight
This calculation makes two assumptions ,neither of which is valid ,namely that the factor of the titrant to be used in the assay is 1.000 and that the sample is 100 % pure .Neither of these assumptions is true,but the factor will be close to 1.000 and the purity will usually be close to 100% , so the estimate is worth doing .The approximate titre calculation is also the first sign the analyst has that things are going wrong in the assay .If the approximate titre is estimated as (say ) 18 ml , alarm bell should begin to ring if no end point has been reached after approximately 20 ml . One truth is that the analaysts are ,by nature ,lzy and do not want to refill the burette during a titration.
This calculation makes two assumptions ,neither of which is valid ,namely that the factor of the titrant to be used in the assay is 1.000 and that the sample is 100 % pure .Neither of these assumptions is true,but the factor will be close to 1.000 and the purity will usually be close to 100% , so the estimate is worth doing .The approximate titre calculation is also the first sign the analyst has that things are going wrong in the assay .If the approximate titre is estimated as (say ) 18 ml , alarm bell should begin to ring if no end point has been reached after approximately 20 ml . One truth is that the analaysts are ,by nature ,lzy and do not want to refill the burette during a titration.
tags: assay,titration calculations,assay calculation,shortcuts for titration, assay of compounds,calcuation of titre volume, detection of end point, titre volume without doing titration
