titration without water

2. Contents
Introduction
Why Non-aqueous Titrations
Theory
Advantages
Disadvantages
Effect of Temperature on Assays
Non-aqueous Solvents
Properties of solvents
Role of Solvents
Types of Solvents
Selection of Solvent
Leveling and Differentiating Effect
Detection of End Point
Applications

10. Arrhenius Theory
This is talk about the dissociation of
compound in aqueous solution to describe
its acidic or basic character
But
In Non-aqueous Titration, Water is
not take apart in titration.
So.,
It can't be applied for this

11. Lowry-Bronsted Theory
 The ability of substances to act as acids or
bases depend on the choice of solvent system.

13.  Organic acids and bases that are insoluble in water
are soluble in non-aqueous solvent.
 Organic acid, which is of comparable strength to
water, can be titrated easily in non-aqueous solvent.
Bases also follow the same rules.
 A non-aqueous solvent may help two are more acids
in mixture. The individual acid can give separate
end point in different solvent.
 By the proper choice of the solvents or indicator, the
biological ingredients of a substance whether acidic
or basic can be selectively titrated.

15.  Temperature ,moisture,co2 should be control
 Solvents are expensive
 Volatile solvents can pollute environment
 Indicator must be prepare in non-aqueous
medium.

17. Effect of Temperature on Assays
Non-aqueous solvents possess greater
coefficients of expansion as compared to water,
so there is effect of temperature.
The volume of titrant may be corrected by the
application of the following formula :
Vc = V [1 + 0.001 (tl + t2)]
Vc = Corrected volume of titrant,
V = Volume of titrant measured,
tl = Temperature at which titrant was standardized,
t2 = Temperature at which titration was performed.

19. Capacity of Self-dissociation
Dielectric Constant
Acid-Base Character of Solvent

20. The capability of the compound to store
the electric charge.
The dielectric constant of a solvent is
the ratio of the capacity of a condenser
filled with the solvent to the capacity of the
empty condenser.
Dielectric Constant

21. Strength of the compound varies based on
atmospheric conditions that’s in turns says the effect
of solvent
In non aqueous solvents the acidity is decreases in
the following order
HCIO4> HBr>H2SO4>HCI>HNO3
HCl in water…….strongly acidic
HCl in acetic acid……weakly acidic
Acetic acid in water……weakly acidic
Acetic acid in ammonia….strongly acidic

22. The solvents are divided into 4 groups
 Aprotic solvents
 Protophilic solvents
 Protogenic solvents
 Amphiprotic solvents

23. Aprotic solvents (inert solvents) :
 Aprotic solvents(inert solvents)
 Aprotic solvents are neutral, chemically inert
substances such as benzene and chloroform.
 They have a low dielectric constant, do not react
with either acids or bases and therefore do not
favor ionization. The picric acid gives a colorless
solution in benzene or toluene which becomes
yellow on adding aniline shows that picric acid is
not dissociated in benzene or toluene solution.
 This type of solvents neither accept or donate
protons
Ex:-Benzene , dioxan , chloro-benzene, chloroform, ethyl
acetate, carbon tetra chloride.

24. Protophilic solvent :
Protophilic solvent Basic in character and react
with acids to form solvated proton
HB + Sol. ⇌ Sol.H + B
Acid + Basic solvent ⇌ Solvated proton + Conjugate base of acid
A weakly basic solvent has less tendency than a
strongly basic one to accept a proton.
Similarly a weak acid has less tendency to donate
protons than a strong acid.
Ex:-acetone , ethers, pyridine ,liquid ammonia

25. Protogenic solvents :
Protogenic solvents Acidic in nature and donte
protons
Ex:- sulphuric acid , formic acid, propionoic
acid ,acetic anhydride etc.
They have high dielectric constant and ionised
 Because of their strength and ability to donate
protons.

26. Amphiprotic solvents :
Amphiprotic solvents have both protophilic and
protogenic properties.
This can accept or donate protons.
They are dissociated to a slight extent
Ex:-water , alcohols, acetic acid

27. Solubility of the sample
Nature of the sample
Should produce sharp end point
Should have high dielectric point
Should be of low toxicity
Should be easily purified
Should be in expensive

30. Potentiometric titration
Indicator method

31. Potentiometric titration :
Potentiometric method for the detection
of the equivalence point
The end point is determined by using
indictor electrode (glass electrode) and
reference electrode (saturated calomel
electrode)

32. Indicators for Non-Aqueous Titrations :
The ionized and unionized or the different
resonant forms of indicators are apply equally well for
non-aqueous titrations but their colour changes at the
end point vary from titration to titrations, as they
depend on the nature of the titrant.
The colour corresponding to the correct end
point may be established by carrying out a
potentiometric titration while simultaneously
observing the colour change of the indicator.

33. The important indicator used for non-aqueous titration
are follow:
Crystal violet : It is used as 0.5% solution in glacial
acetic acid, it gives violet color in basic medium and
yellowish green in acidic medium. It is most widely use
for the titration of pyridine with perchloric acid.
Oracet Blue B Indicator: It is prepared o.5% glacial
acetic acid. It gives blue colour in basic medium while
pink colour in acidic medium.
Quinaldine Red Indicator: It is used 0.1% solution in
methanol/ethanol. Methanol is more stable. It gives
yellow colour in basic medium while almost colourless
in acidic medium.

36. Non Aqueous Titration of weak Bases :
Solvents used in the titration of weak bases;
Neutral solvents :
Ex: Alcohol, chloroform,benzene,chlorobenzene
Acidic solvents:
Ex: Formic acid, glacial acetic acid, propionic acids
Titrant used in the titration of weak bases:
Ex: Perchloric acid
Indicators used in the titration of weak bases
Ex: Oracat blue ,crystal violet,
1-naphtholbenzein (weak bases)
methyl red,
methyl orange & thymol blue (stronger bases)

37. Non Aqueous titration of weak acids :
Many weakly acidic substances (alcohol or
aprotic solvent)can be titrated in an appropriate non
aqueous solvents with a sharp end point .
Ex:- acidic halides, acids, amino acids, enols
(barbiturates, xanthenes), phenols, pyroles and
sulphonamides etc,.

38. Solvents used in the titration of weak acids:
Ex: Ethylenediamine,n-butylamine,morpholine
Titrant used in the titration of weak acids:
Ex: Sodium methoxide, lithium methoxide,
potasium methoxide ,tetrabutyl ammonium
hydroxide etc.
Indicators used in the titration of weak acids
Ex: azo violet, thymol blue, thymolphthalein.,
O-Nitro aniline