Titration, also known as titrimetry, is a technique used to determine the concentration of an unknown solution by reacting it with a solution of known concentration. The principle of titration is based on a complete chemical reaction between the analyte and titrant. Key terms in titration include the analyte, which is the unknown solution, and the titrant, which is the standard solution of known concentration. Titration calculations rely on the law of equivalence, which states that the amount of reactants must be equivalent at the endpoint of the reaction. Titration is used in various fields such as agriculture, oil industry, chemical industry, pharmaceuticals, and food industry due to its accuracy, precision, and cost effectiveness.
2. CONTENTS
• Introduction
• Principle of titration
• Terms used in titration
• Concentration Terms
• Titrimetric calculation
• Titrimetric apparatus
• Types of titration
• Fields of use
• Advantages of titration
3. Introduction:- A technique for determining
the concentration of a solution by
measuring the volume of one solution
needed to completely react with another
solution. Titration process involves addition
of solution of known conc. from burette to
the measured volume of analyte.
4. Principle of titration:- It is based on the
complete chemical reaction between the
analyte and the reagent (titrant) of known
concentration.
Analyte + Titrant → Product
5. Terms used in titration
Analyte:- The solution of unknown
concentration but known volume.
Titrant:- The solution of known
concentration.
6. Standard solution:- A solution of known
concentration is called the standard solution.
Types of standard solution:-
1) Primary standard:- It has certain
properties:-
(a)Extremely pure.
(b)Highly stable.
(c) Can be weighed easily.
For e.g. Na2CO3,
KHP
7. Secondary standard:- It has certain
properties:-
(a) Less pure than primary standard.
(b) Less stable than primary standard.
(c) Can not be weighed easily.
For e.g. NaOH, HCl
8. Euivalence Point:- Point where the amount of
two reactants are just equivalent .
End point:- Point at which the reaction is
observed to be complete, this point is usually
observe with the help of indicator.
9. Indicator:- An auxiliary substance which helps
in the usual detection of the completion of the
titration process at the end point.
For examples:- Methyl orange,
Phenolphthalein, Cresol red, Thymol blue.
10. Concentration Terms:-
The concentration of standard solutions
(titrants) are generally expressed in units of
either molarity (CM, or M) or normality (CN,
or N).
Molarity (M):-It is the number of moles of a
solute per liter of solution.
11. Normality:- It is the gram equivalent weight
of solute dissolved per litre of solution.
Molality:- It is the number of moles of solute
present in per kilogram of solvent.
12. Titrimetric calculation :-
It is based on the following law of equivalence:-
NaVa = NsVs
or
MaVa = MsVs
Where, Na is the normality of analyte.
Va is the volume of the analyte.
Ns is the normality of standard solution.
Vs is the volume of standard solution used.
Ma is the molarity of analyte.
Ms is the molarity of standard solution.
15. Acid – base Titration( neutralization):-A
sample of unknown concentration of acid is
estimated with a known concentrated base or
vice-verse.
acid + base → water + salt
HCl + NaOH ------> H2O + NaCl
16. Titrimetric curve and types of acid - base
titration:-
Titration curve:-A titration curve is a
graph of the pH as a function of the
amount of titrant (acid or base) added.
21. Complexometric Titrations:- As the name
indicates, the end point is seems by formation of
a complex molecule. Here titrant and titrand
react to form a complex till end point is reached.
Once complex is formed, the complex is stable
and not further reaction takes place.
Ca+2 + EDTA-4 ------> CaEDTA-2
Mg In + EDTA-4 ------> MgEDTA-2 + In-2
22. Redox titration:- Redox titration is based on
the redox reaction (oxidation-reduction)
between analyte and titrant.
For example:-
6 Fe2+ + 14 H+ + Cr2O7
2- => 6 Fe3+ + 2Cr3+ + 7 H2O
MnO4
- + 8 H+ + 5 Fe2+==>Mn2+ + 5 Fe3+ + 4 H2O
23. Precipitation titrations:- The titrations which
are based on the formation of insoluble
precipitates, when the solutions of two
reacting substances are brought in contact
with each other, are called Precipitation
titration.
Ag+(aq)+Cl−(aq)⇌AgCl(s)
24. Methods of precipitation titration:-
Mohr ‘s method:- It involve formation of colored
precipitate at the end point .
Volhard ‘s method:- It involves formation of
soluble colored complex at the end point.
Fajan’s method:- It involves adsorption of a
colored indicator on the precipitate at the end
point.
25. Fields of use:-
Titration is a widely applied analytical
technique. Some areas where titration is used
are given below:-
Agriculture, Oil Industry, Chemical industry,
Pharmaceuticals, Food Industry.
26. Advantages of titration :-
There are several reasons why titration is
used in laboratories worldwide:-
1)Titration is an established analytical
technique.
2)It is fast .
27. 3) It is a very accurate and precise technique.
4) Titration offers a good price/performance
ratio as compared to more sophisticated
techniques.
6) It can be used by low-skilled and low-
trained operators.
7) No need for highly specialized chemical
knowledge.