Learning objectives Introduction Conditions For Volumetric Analysis Terms In Volumetric Analysis Primary Standard Methods Of Expressing Concentrations In Volumetric Analysis Types of Titration Methods Classification Of Titrimetric Or Volumetric Methods Conclusion References

1. Prepared by
G. Nikitha, M.Pharmacy
Assistant Professor
Department of Pharmaceutical Chemistry
Sree Dattha Institute Of Pharmacy
Hyderabad
Subject: Pharmaceutical Inorganic Chemistry
Year: Pharm-D 1st Year

2. CONTENTS
 Learning objectives
 Introduction
 Conditions For Volumetric Analysis
 Terms In Volumetric Analysis
 Primary Standard
 Methods Of Expressing Concentrations In Volumetric Analysis
 Types of Titration Methods
 Classification Of Titrimetric Or Volumetric Methods
 Conclusion
 References

3. LEARNING OBJECTIVES
In These topic we will discuss
 Introduction to Analytical chemistry,
 Qualitative Analysis and Quantitative Analysis
 Introduction to Volumetric Analysis
 conditions for Volumetric Analysis
 Terms in Volumetric Analysis
 Primary Standard
 Methods Of Expressing Concentrations In Volumetric Analysis
 Types of Titration Methods
 Classification Of Titrimetric Or Volumetric Methods

4. INTRODUCTION TO ANALYTICAL
CHEMISTRY

5. INTRODUCTION TO ANALYTICAL CHEMISTRY
 It is the branch of chemistry which deals with the analysis of substances. It is
mainly divided into two parts
1. Qualitative Analysis
2. Quantitative Analysis

6. 1. Qualitative Analysis: Qualitative Analysis is primarily concerned with the
identification of the constituents present in a chemical substance or a mixture of
substance.
2. Quantitative Analysis: Quantitative Analysis is primarily concerned with the
exact determination of the quantity of the constituents present in a chemical
substance or a mixture of substances.
Quantitative Analysis is carried out mainly for determining the purity of
chemical substances. The methods used for the determination of purity are
called assay methods. There are many methods of quantitative analysis such as
volumetric Analysis, gravimetric Analysis, refractometry, polarimetry,
fluorimetry, photometry, electochemical methods, chromatograhic methods etc.
volumetric Analysis is also known as titrimetric analysis.

7. INTRODUCTION TO VOLUMETRIC ANALYSIS
 Volumetric analysis is a mode of quantitative analysis which is based on the
determination of the volume of a solution of known concentration (standard)
required to react quantitatively with a solution of the substance to be analyzed.
 The substance to be analyzed is called the titrate, the reagent of known
concentration which is added to the solution of the substance to be analyzed is
called titrant.
 In Volumetric analysis, two solutions are always made to react in a conical flask
known as titration flask. One of these solutions is taken in a burette and other in
the titration flask. Then solution from burette is added to the titration flak. The
process of finding out the volume of the volume of the titrant (standard
solution) required to react completely with a known volume of solution under
analysis is known as titration.

8.  The exact point at which reaction is completed during titration is called end
point or equivalence point.
 In order to recognize the end point certain substances, called indicators, are
added which exhibit a marked colour change at the completion of the chemical
reaction.
 In the ideal titration the visible end-point will coincide with the theoretical end
point.
 In practice however a small difference occurs. This difference is termed as
titration error. The choice of indicator should be such that the titration error is as
small as possible.

9. CONDITIONS FOR VOLUMETRIC ANALYSIS
Estimation by volumetric analysis is only feasible if the reaction involved fulfils
the following conditions:
 Chemical reaction must be simple and should takes place quantitatively
according to a definite equation to form known products. It should represented
by a chemical reaction.
 The reaction should be instantaneous under the experimental conditions
maintained.
 The reaction should take essentially to completion under the experimental
conditions maintained.
 The end point should be well defined either between the reacting substances or
by the use of an indicator.

10. TERMS IN VOLUMETRIC ANALYSIS
Some terms must be known before studying the volumetric analysis.
They are
Titrate: The substance to be determined is termed as the titrate.
Titrant: The substance of known concentration is termed as titrant.
Titration: The process of determining the volume is termed as titration.
End Point: The point at which the reaction is complete is termed as end point.
Indicator: Some auxiliary substance which is used to detect the end point of the
titration is termed as the indicator.
Standard Solution: The solution of known concentration is termed as the stardard
solution.

12. PRIMARY STANDARD
A standard solution can be obtained by dissolving a definite weight of a
substance having known purity called a primary standard in a definite volume.
The solution of this substance can be used as a titrant. There are very few
substances which can be used as primary standard substances.
Example: arsenic trioxide (As2O3), potassium dichromate (K2Cr2O7), potassium
bromate (KBrO3) potassium iodate (KIO3)
Properties:
 High purity
 Stability (low reactivity)
 Low hygroscopicity (to minimize weight changes due to humidity)
 High equivalent weight (to minimize weighing errors)
 Non-toxicity
 Ready and cheap availability

13. SECONDARY STANDARD
Secondary standard is a chemical that has been. standardized against a
primary standard for use in a. specific analysis. Secondary standards are
commonly used to calibrate analytical methods. A secondary standard is a
substance which may be used.
Example: Sodium Hydroxide (NaOH), Sodium Chloride (NaCl), Sodium
carbonate (Na2CO3)
Properties:
 It has less purity than primary standard.
 Less stable and more reactive than primary standard. But its solution remains
stable for long time.

14. METHODS OF EXPRESSING CONCENTRATIONS
IN VOLUMETRIC ANALYSIS
In volumetric analysis the various concentration terms are used. Normality and
molarity are most frequent terms to express the concentration.
Normality: It may defined as the number of gram equivalent weight of solute
present one liter of solution. It is represented by “N”.

15. Example:
1. How do you prepare and standardize 0.1N sodium hydroxide solution
Ans:
Formula for Normality
Gram equivalent weight of sodium hydroxide (NaOH) is 40
Molecular weight of sodium = 23
Molecular weight of Oxygen= 16
Molecular weight of hydrogen = 1
Number of hydrogen proton present in sodium hydroxide=1

16. One Normality of sodium hydroxide (NaOH) =
40grams of sodium hydroxide (NaOH) is dissolved in 1000ml or one liter of
solution.
For 0.1 One Normality of sodium hydroxide (NaOH)
_____ grams of sodium hydroxide (NaOH) is dissolved in 1000ml or one liter of
solution.
40grams of sodium hydroxide (NaOH) - one liter --- One Normality
__grams of sodium hydroxide (NaOH) - one liter --- 0.1 Normality
For 0.1 One Normality of sodium hydroxide (NaOH)
4 grams of sodium hydroxide (NaOH) is dissolved in 1000ml or one liter of
solution.

17. 2. How do you prepare 100ml of 0.1 N oxalic acid solution?
Ans:
Formula for Normality
Oxalic acid is a dibasic acid and available in crystalline form as. (C2H2O4) 2H20.
Gram equivalent weight of oxalic acid is 63
Equivalent weight of Oxalic acid = (Molecular weight / 2) = (126 / 2) = 63 g
To prepare 1000 ml of 1 N Oxalic acid solution, the amount of oxalic acid required
= 63 g.
Number of hydrogen proton present in Oxalic acid = 2

18. One Normality of Oxalic acid =
63 grams of Oxalic acid is dissolved in 1000ml or one liter of solution.
But as per the given question we have to make the normality for 100 ml solution
So 63 grams of Oxalic acid (NaOH) - one liter --- One Normality
_____ grams of Oxalic acid (NaOH) – 100 ml --- One Normality
6.3 grams of Oxalic acid (NaOH) – 100 ml --- One Normality
___grams of Oxalic acid (NaOH) – 100 ml --- 0.1 Normality
0.1 Normality of Oxalic acid =
0.63 grams of Oxalic acid is dissolved in 100ml or one liter of solution.

19. 3. If 0.98 grams of sulphuric acid H2SO4 are present in 500ml of solution. Find
Normality?
Ans:
Formula for Normality
Here n is Number of hydrogen proton present in sulphuric acid =2
Gram equivalent weight of sulphuric acid (H2SO4) is 49
Molecular weight of sodium = 23x1 =23
Molecular weight of Oxygen= 16x4 =64
Molecular weight of hydrogen = 1x2 =2

21. Molarity: Molarity of a given solution is defined as the total number of moles of
solute per litre of solution. It is represented by M.
Formula:
Here,
M is the molality of the solution that is to be calculated
n is the number of moles of the solute
V is the volume of solution given in terms of litres

22. Example:
A solution prepared using 15 g of sodium sulphate. The volume of the solution is
125 ml. Calculate the molarity of the given solution of sodium sulphate.
Solution:
The molecular formula for sodium sulphate is Na2SO4.
The molecular formula for water is H2O.
The molecular mass of sodium sulphate is calculated as given below,
M=23×2+32+16×4=142
The number of moles of sodium sulphate in the given question is calculated as,

23. The volume of the solution is 125 ml.
Expressing the above values in terms of litres,
Now, using the formula given above, we calculate the molarity of the given
solution.
Substituting the values, we get,
The molarity of the given solution is 0.85M.

24. Molality: The molality of a solution may be defined as number of moles of solute
per 1000g of solvent. It is represented by “m”.
Molality (m) = moles of solute / kilograms of solvent
Students have to remember that molality is used to measure the moles in relation to
the mass of the solvent and not the mass of the solution.

25. MOLALITY VS MOLARITY
Molality and Molarity are terms that are often confused and some students even use
it interchangeably. However, these are two different measures for representing
the concentration of a chemical solution. They are also used in different
instances. We will look at the differences between molality and molarity below.
Molality Molarity
1. It is the number of moles of
solute per kilogram of solvent.
1. It is the number of moles of
solute per liters of solvent.
2. Change in temperature will not
affect this unit of concentration.
2. The unit will change with change
in temperature.
3. Its unit is mol/kg. 3. Its unit is mol/litre.
4. Denoted by the letter (m). 4. Denoted by the letter (M).

26. Weight per cent: It specifies the number of grams of solute per 100 grams of
solution.
mole fraction: It is defined as moles of solute divided by the total moles. No unit.
Total mole solution = mole of solute + mole of solvent
Equivalent weight: The mass of a particular substance that can combine with or
displace one gram of hydrogen or eight grams of oxygen, used in expressing
combining powers, especially of elements.

27. TYPES OF TITRATION METHODS
It is possible to carry out titrimetric analysis using either of following methods:
1. Direct Titration: In these method, the solution of the substance to be
determined quantitatively is directly titrated with a suitable titrant by using an
appropriate indicator or a suitable instrument to locate the equivalent point.
Example: The titration of strong acids such as HNO3, H2SO4 and HCl etc. with
strong alkalis such as NaOH, KOH or magnesium salt solution with EDTA solution
etc.
2. Back Titration: This titration is followed when the direct titration is not
possible. This method is used for those substances which are not water soluble or
which are weak acids or bases by nature
Example: ZnO, alkaloids etc.

28. In these method, the substance to be estimated quantitively is dissolved in a known
sufficient volume of a standard solution of acid or alkali. The excess of acid or
alkali remaining in the solution is back titrated by using a suitable indicator. A
black determination (without substance) is done from which the difference is
volume required for the substance is found out.
3. Indirect Titration: When substance is not directly titrable employing a
chemical reaction it can be precipitated or removed from the reaction and the
reaction product thus formed has to be titrated.

29. CLASSIFICATION OF TITRIMETRIC OR
VOLUMETRIC METHODS
Depending upon the nature of chemical reactions, it is possible to classify various
types of titrimetric methods into the following types:
1. Acid-Base Titrations
2. Redox titrations
3. Precipitation titrations
4. Complexometric titrations
5. Non aqueous titrations
6. Diazotizations titrations

30. CONCLUSION
In these topic we have discussed
 Introduction to Analytical chemistry,
 Qualitative Analysis and Quantitative Analysis
 Introduction to Volumetric Analysis
 conditions for Volumetric Analysis
 Terms in Volumetric Analysis
 Primary Standard
 Methods Of Expressing Concentrations In Volumetric Analysis
 Types of Titration Methods
 Classification Of Titrimetric Or Volumetric Methods

31. REFERENCES
 Pharmaceutical Chemistry -Inorganic Volume-1 by G. R. Chatwal.
 Essentials of Inorganic Chemistry by Katja A. Strohfeldt.
 Indian Pharmacopoeia.
 M.L Schroff, Inorganic Pharmaceutical Chemistry.
 P. GunduRao, Inorganic Pharmaceutical Chemistry, 3rd Edition
 A.I. Vogel, Text Book of Quantitative Inorganic analysis.
 Bentley and Driver's Textbook of Pharmaceutical Chemistry.

32. THANK YOU