VOLUMETRIC ANALYSIS Flashcards
the determination of the
volume of a solution of
known concentration
required to react with a
given amount of a
substance to be analyzed.
Volumetric
Analysis
What is the importance of
volumetric analysis?
It is used in
determining the
purity of drugs
Food industry –
determination of
salt, vit and fatty
acid content.
Water treatment
– determination
of contaminants
and pH
a common laboratory method of quantitative chemical
analysis where a solution of known concentration is used
to determine the concentration of an unknown solution.
TITRATION
Parts of a titration set-up
- Analyte/Titrand
- Standard solution/ Volumetric Solution/ Titrant
- Indicator
a solution which
concentration is
accurately known.
Standard solution
the
chemical substance
being analyzed or the
active constituent in
the sample.
Analyte
a chemical
which changes
color at or very
near the endpoint.
Indicator
point during a titration when an indicator shows that
the amount of reactant necessary for a complete
reaction has been added to a solution
Endpoint (practical
s the theoretical point at which equivalent amounts
of each substance have reacted
Equivalence point or stoichiometric point or
theoretical endpoint
reaction between an acid and
a base to form salt of water
Neutralization
reactions that from an
insoluble precipitate
Precipitimetry
reaction between metal ions
and a ligand
Complexometry
reaction that involves the
transfer of electrons
Redox titration
Chemical substance, which changes color at or
very near the endpoint.
INDICATORS
Used to avoid errors during titration
INDICATORS
INDICATORS Referred to as
TS or Test Solutions
TS or Test Solutions Usual concentration is
0.05%, with 0.1 to 0.2 ml
of indicator used for 10 ml of the analyte
pH range; Acid; Base
Malachite green
0 – 2.0; Yellow; Green
pH range; Acid; Base
Methyl orange
3.2 -4.4 Pink Yellow
pH range; Acid; Base
Methyl red
4.2 – 6.2 Red Yellow
pH range; Acid; Base
Bromothymol
blue
6.0 – 7.6 Yellow Blue
pH range; Acid; Base
Phenolphthalein
8 - 10 Colorless Pink or red
pH range; Acid; Base
Thymol blue
8 – 9.2 yellow blue
Weak Acid Strong Base INDICATOR
Phenolphthalein
Weak Base Strong Acid INDICATOR
Methyl red
Strong Acid Strong Base INDICATOR
Phenolphthalein,
Methyl Orange,
Methyl Red
Weak Base Weak Acid INDICATOR
NONE – No
endpoint
PRECIPITATION INDICATORS
- Dichlorofluororesc ein
- Eosin Y
- Potassium Chromate
- FAS
COMPLEXATION INDICATORS
- Dithizone
- Eriochrome Black
- Hydroxynaphtol Blue
REDOX INDICATORS
- Iodine TS
- Potassium
Permangana
te VS - Starch TS
number of
moles of reactive unit
in a compound which
reacts or takes the
place of one mole of
Hydrogen ion
Equivalent
Equivalent of salts
Valence of cation
weight that is
chemically equivalent
to the reacting power
of one of one atomic
weight of hydrogen.
Equivalent weight
called milliequivalent
weight
1/1000 of Eq. weight
strength in grams equivalent to milliliter of
standard solution or the weight of a substance
chemically equivalent to 1 ml of a standard
solution.
TITER
no. of equivalents of solute per liter
NORMALITY
1N
NORMAL SOLUTION
2N
DOUBLE NORMAL
0.5N
HALF NORMAL
TENTH NORMAL
0.1N
TWENTIETH NORMAL
0.05N
HUNDREDTH NORMAL
0.01N
THOUSANDTH NORMAL
0.001N
refers to the no. of moles of solute per liter of solution
MOLARITY
refers to the no. of moles of solute per kilogram of solvent
MOLALITY
a solution of known concentration or a solution
whose exact concentration is known
STANDARD SOLUTION
Standard acid solution
HCl, H 2SO 4, HClO
Standard alkali solution
NaOH, KOH,
CH 3ONa
Process of determining exact concentration of a
solution.
STANDARDIZATION
Types of volumetric solution:
- Primary Standard 2. Secondary Standard
chemically pure solid substance almost 99.9%
pure used in the standardization of a solution
Primary Standard
Other requirements for primary standard are:
- It must be easy to prepare and pure.
- It must be of definite known composition.
- It must be stable.
- It must react stoichiometrically with the substance
present in the solution. - It must be soluble in water.
- it must have a fairly high equivalent weight.
Primary Standard for acid solutions:
Anhydrous
Na2 CO 3
CaCO 3
THAM
Primary Standard for alkali solutions:
Benzoic acid
Potassium
biphthalate
Sulfamic acid
substance that is not
necessarily pure but whose exact purity is
known.
Secondary Standard
A standard solution is a commonly used
secondary standard
to standardize only one of
the solutions by using a primary standard and
the other is standardized by using a
secondary standard
Common practice
Titrate with HCl
until a _________ is
achieved even after
boiling the solution.
permanent
faint pink color
