2. ANALYSIS
• Chemists are the people concerned with
ANALYSIS.
• Analysis is the process of learning nature and
composition of any substance.
3. CLASSIFICATION
• The THREE important questions generally
studied in ANALYSIS are….
• WHAT ??????
• HOW MUCH????
• WHERE ???
4.
5. But for a chemist………………
• WHAT does it consist?
• HOW MUCH each of the constituent is ?
• WHERE from it was bought?
• Answer for the first question………..
• It consists of flour, sugar, cashew, ghee,
kishmish, ilachi……..
6. • Answer for the second question……
500g of flour; 300g of sugar; 100g of cashew;
100g of kishmish; 500g of ghee; 5g of ilachi.
Answer for the third question is……
bought from
XYZ Sweet store (ISO:9000 certified)
7. God blessed us with the two
wonderful organs for both the
QUALITATIVE ANALYSIS
and
QUANTITATIVE ANALYSIS
EYES are for Qualitative Analysis and
TONGUE is for Quantitative analysis
with limitations
8. • QUALITATIVE ANALYSIS is the process of
identification of each of the constituent
present in a sample provided.
• QUANTITAIVE ANALYSIS is the process of
determination of the QUANTITY of each of the
constituent present in the sample.
9.
10.
11.
12.
13. It was mainly based on classical gravimetric and titrimetric
schemes followed by the invention of a precise analytical
balance - extremely low throughputs and highly precise and
accurate analyses with restricted sensitivity (detection up to fraction
of a per cent only).
Gravimetry is the determination of an element or species through the
measurement of the mass of a well-characterized insoluble product of a
definite chemical reaction involving that element or species
Gravimetry
14. • When NaCl solution is
mixed with a solution
of silver nitrate it
forms a precipitate of
silver chloride
15. Titrimetry
Titrimetry is the determination of an element or species through
the measurement of mass of a chemical necessary to exactly
complete a definite chemical reaction in
a solution containing that element or species
End points generally are determined by observing a color change
in an indicator.
Endpoints are also commonly determined by observations of
potential differences
at electrodes, or changes in conductivity
16.
17. TERMS USED IN VOLUMETRIC
ANALYSIS
• TITRATION The process, operation, or method of
determining the concentration of a substance in solution by
adding to it a standard reagent of known concentration in
carefully measured amounts until a reaction of definite and
known proportion is completed, as shown by a color change or
by electrical measurement, and then calculating the unknown
concentration.
• TITRATE The reagent of known concentration in the
process of titration.
18. • TITRANT the solution in a titration that is added from
a burette to a measured quantity of another solution.
19. • INDICATOR a
substance used in
titrations to indicate
the completion of a
chemical reaction,
usually by a change
of colour.
21. • ENDPOINT The point in a titration at which no
more titrant should be added. It is
determined, for example, by a color change in
an indicator or by the appearance of a
precipitate.
• (In the above picture we can clearly observe
the endpoint)
22. • ERROR is defined as the difference between
the true value and observed value. The
following are the different types of errors
generally seen.
• Physical error
• Experimental error
23. • Parallax is a deceptive change
of the position of an object
which is observed while the
position of the observer
changes. Position of eye at all
volumetric vessels must be at
the same level as the
meniscus. If not, the parallax
will cause an error while
reading the position of the
meniscus of a liquid in a
burette. It will be a positive
mistake if the eye is lower, and
negative if the eye is higher
than the meniscus plane
24. Experimental error
• These errors are due to………..
1.Preparation of solutions and reagents
2.Concentration of reagents and indicators
3.Weighing the required chemical substances
4.Addition of reagents from graduated
apparatus such as burette pipette etc
25. AACURACY AND PRECISION
• ACCURACY is defined as the NEAREST
approach to the true value……
• For example if the % of iron in iron ore is
theoretically 74 and that of the reported is
73.8 then the reported value is said to be
accurate. And if the reported value is found to
be 67.5 then the value is not accurate.
26. • PRECISION is defined as REPEATABILITY AND
REPRODUCIBILITY of the REPORTED value
which is found to be accurate….
Accurat
e value
Day1 Day2 Week1 Week2 Month
0.049 0.049 0.049 0.049 0.049 0.048
0.048 0.048 0.048 0.048 0.048 0.047
0.049 0.049 0.049 0.049 0.049 0.048
0.049 0.049 0.049 0.049 0.049 0.048
0.049 0.049 0.049 0.049 0.049 0.048
27.
28. ROLE OF INDICATOR……
• An indicator in a titration plays key role by
detecting the END POINT. The indicator
shows a different and distinct colour change
at the point of addition of excess of drop of
reagent from burette. It works accurately on
some conditions such as pH, medium (acidic
or alkaline) and on potentials.
29. ACID BASE TITRATIONS
• An acid-base titration is the determination of the
concentration of an acid or base by exactly neutralizing the
acid/base with an acid or base of known concentration.
• Before starting the titration a suitable pH indicator must be
chosen.
• The pH of the equivalence point can be estimated using
the following rules:
1. A strong acid will react with a strong base to form a neutral
(pH=7) solution.
2. A strong acid will react with a weak base to form an acidic
(pH<7) solution.
3. A weak acid will react with a strong base to form a basic
(pH>7) solution.
30. REDOX TITRATIONS
• Redox titration (also called oxidation-reduction
titration) is a type of titration based on a
redox reaction between the analyte and titrant.
• Redox titration may involve the use of a
redox indicator and/or a potentiometer.
• Oxidation is defined as the addition of oxygen
or removal of hydrogen or loss of electrons.
For example, in the extraction of iron from its
• Fe(II)
31. • Reduction id removal of oxygen or addition of
hydrogen or gain of electrons
• A redox reaction is a simultaneous oxidation
and reduction process
32. COMPLEXOMETRIC TITRATIONS
• Complexometric titration is a form of
volumetric analysis in which the formation of a
colored complex is used to indicate the end point of
a titration. Complexometric titrations are particularly
useful for the determination of a mixture of different
metal ions in solution.
• The indicators used here are called as
METALLOCHROMIC INDICATORS.
33. • Metal +In→ [M-In]
• M-In is metal indicator complex
• [M-In]+EDTA → [M-EDTA]+In
34. PRECIPITATION TITRATIONS
• The titration, which involves the formation of
precipitate during the course of a titration.
• The first drop of titrant in excess will react
with an indicator resulting in a color change
and indicating the end point of the titration.
35. SELECTION OF INDICATORS
• ACID BASE INDICATORS: Acid - Base indicators (also
known as pH indicators) are substances which change colour
with pH. They are usually weak acids or bases, which when
dissolved in water dissociate slightly and form ions.
Consider an indicator which is a weak acid, with the formula
HIn. At equilibrium, the following equilibrium equation is
established with its conjugate base:
HIn(Aq) +H2O -------H3O+
+In-
37. • A redox indicator (also called an oxidation-reduction
indicator) is an indicator that undergoes a definite
color change at a specific electrode potential.
• The requirement for fast and reversible color change
means that the oxidation-reduction equilibrium for an
indicator redox system needs to be established very
fast. Therefore only a few classes of organic redox
systems can be used for indicator purposes.
38. • There are two common type of redox indicators:
• metal-organic complexes (Ex. phenanthroline)
• true organic redox systems (Ex. Methylene blue)
• Sometimes colored inorganic oxidants or reductants
(Ex. Potassium manganate, Potassium dichromate)
are also incorrectly called redox indicators. They can’t
be classified as true redox indicators because of their
irreversibility.
• Almost all redox indicators with true organic redox
systems involve a proton as a participant in their
electrochemical reaction. Therefore sometimes redox
indicators are also divided into two general groups:
independent or dependent on pH.
39. • Internal indicator means that the substance used as
an indicator is actually added to the reaction flask
and this flask changes colour once the end point has
been reached.........examples include diphenylamine
and ferroin.
• External indicators are not added to the reaction
flask....these are used ONLY WHEN A SUITABLE
INTERNAL INDICATOR IS UNAVAILABLE because
these indicators take a lot of time to calculate
examples are potassium ferricyanide
40. Metal ion indicator……………
• To carry out metal cation titrations using EDTA, it is
almost always necessary to use a complexometric
indicator to determine when the end point has been
reached. Common indicators are organic dyes such
as Fast Sulphon Black, Eriochrome Black T,
Eriochrome Red B or Murexide.een displaced from
the metal cations in solution, and that the endpoint
has been reached. Thus, the free indicator (rather
than the metal complex) serves as the endpoint
indicator. These are also called as
METALLOCHROMIC INDICATORS
