Page 55 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

Types of Titration Methods

1. Direct titration. 2. Back (Residual) titration.

3. Displacement (Substitution) titration.

1. Direct Titration

It means stepwise addition of the standard solution (titrant)

from the burette into the solution being analyzed until the

end point is reached.

i.e. Titration of sample ≠ standard (titrant)

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

of the standard

2. Back (Residual) Titration

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 remaining

unreacted excess (residual) of the standard is back titrated against another suitable

standard.

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

subtracting the E.P. which is equivalent to the unreacted amount of the first standard

from the initially added volume (the known added excess).

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

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