Page 21 - PC 101 practical notes 24-25..

MANSOURA NATIONAL UNIVERSIY
PHARM D- CLINICAL PHARMACY LEVEL I PHARM. ANAL. CHEM. I (PC 101)

T Ty yp pe es s o of f t ti it tr ra at ti io on n m me et th ho od ds s

A A) ) D Di ir re ec ct t t ti it tr ra at ti io on n: : 0
{
E.P.
It means stepwise addition of the standard solution (titrant) from Standard
(titrant)
the burette into the solution being analyzed until the end point is

reached. 10 ml sample of
unknown concn.
i.e. Sample of unknown concn. ≠ Standard (titrant)

 Vol. taken from the sample [e.g. 10 ml] ≡ (E.P.) ml of the standard

B B) ) R Re es si id du ua al l t ti it tr ra at ti io on n O OR R B Ba ac ck k t ti it tr ra at ti io on n: :

In this type, a known excess of a standard (more than sufficient to react

with the sample) is added to the sample. Then after the reaction is complete, the

excess unreacted standard is back titrated against another suitable standard.

Part reacts with the sample
i.e. Sample + known excess of standard I

Part remains unreacted

titration of the remaining unreacted part

of standard I ≠ standard II (titrant)

 E.P. ≡ remaining unreacted part

 Sample ≡ reacted part ≡ (known excess added of 1st stand. – E.P.)

The amount of the first standard that reacted with the sample can be calculated

by subtracting the volume consumed in the back titration (E.P.) which is

equivalent to the unreacted amount of the first standard from the initially

added volume (the known added excess).

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