Neutralization Indicators (Aqueous, Non-Aqueous Titration)

Aqueous titration

Strong Acid + Strong Base = Phenolphthalein, methyl red, methyl orange

Aqueous titration

Weak Acid + Strong Base = Phenolphthalein

Aqueous titration

SA + WB = Methyl red

Aqueous titration

WA + WB = No indicator

Non- Aqueous titration

WA + Salt = Crystal violet, methylrosaniline Cl, quinaldine red, Methyl green

Non- Aqueous titration

Relatively SB = Methyl red, Methyl Orange

Non- Aqueous titration

WA = Azo-violet, o-nitro-aniline (very WA)

Non- Aqueous titration

SA = Thymol blue

Acidimetry

It is the direct or residual titrimetric analysis of bases (alkali) using an accurately measured volume of acid.

Direct titration

It is is conducted by introducing a standard acid solution gradually from a buret into a solution of the base being assayed until chemically equivalent amounts of each have reacted as shown by some change in properties of the mixture.

Residual titration

used whenever the end point of a direct titration deviates appreciably from the stoichiometric points of some reasons

1. when the basic sample is insoluble in water

2. the rate of its reaction with the standard acid is relatively slow.

reasons for residual titration

Stoichiometric point (equivalence point)

the theoretical point at which equivalent amount of each (titrant and analyte) have reacted.

Residual or back titration

This is frequently used when the reaction proceeds slowly

Residual or back titration

This is frequently used when the substance to be assayed does not give distinct or sharp end point with an indicator by direct titration

Residual titration

This is carried out by dissolving the substance under examination in an accurately measured quantity of standard solution known to be in excess and titrating the excess of the latter with another standard solution.

Poorly soluble in water and weakly reactive in water

Therapeutic agents for Non-aqueous Titrimetric