CHEMICAL ANALYSIS
BY
Dr.JAGADEESH
CHEMICAL ANALYSIS
• RESOLVING A SAMPLE IN TO ITS
ULTIMATE COMPONENTS
( COMPOUNDS OR ELEMENTS)
IMPORTANCE OF CHEMICAL
ANALYSIS
• IN INDUSTRY: TO CHECK THE QUALITY OF RAW
MATERIAL AND FINISHED PRODUCTS
• IN MEDICINE: TO DIAGNOSE THE DISEASES
• IN FOOD AND AGRICULTURE: TO CHECK THE TOXIC
MATERIALS
• IN ENVIRONMENTAL SCIENCE: TO MEASURE THE
POLLUTANTS IN AIR, WATER AND SOIL
TYPES OF CHEMICAL ANALYSIS
• QUALITATIVE: IT FINDS OUT THE
NATURE OF ELEMENTS OR
COMPOUNDS (IDENTIFIES WHAT IS
INSIDE THE SAMPLE)
• QUANTITATIVE : IT ESTIMATES THE
CONCENTRATION OF THE ELEMENTS
OR COMPOUNDS PRESENT IN A
SAMPLE ( FINDS OUT HOW MUCH?)
METHODS OF CHEMICAL
ANALYSIS
• VOLUMETRIC ANALYSIS ( Involves the measurement of volume of
reacting solutions)
• GRAVIMETRIC ANALYSIS (Involves the measurement of the weight
of a precipitate)
• SPECTROSCOPIC ANALYSIS ( Involves the measurement of light
absorbed or transmitted)
e.g. Visible, UV, Infra-red Spectroscopy and Atomic Absorption
Spectroscopy ( Depending on the nature of light and the source
used)
• Electro-chemical methods : ( Potentiometry, Voltammetry ,
Coulometry) Involves the measurement of potential, Current-Voltage
variation, total electrical Charge passed through the solution etc.
VOLUMETRIC ANALYSIS
• It measures the volume of a solution of
known / unknown concentration reacted
with a definite volume of another solution
of unknown / known.
VOLUMETRIC ANALYSIS
• Also known as Titrimetric analysis.
• Important terms:
Standard Solution: (Titrant )A solution of Known Concentration
Titrand : Solution of unknown Concentration
Titration: Process of adding small quantities of a solution to the other
to find the equivalence point.
Equivalence point: The point at which the reaction between the
titrant and titrand is complete.
Indicator: A reagent used to detect the end point by some physical
change produced by it ( like a colour change)
Essential conditions
• Simple reaction must be possible between
the two solutions and the completion of it
in stoichiometric proportions.
• Reaction must be fast.
• A marked change should be occurring at
the end point.
• An indicator must be available to detect
the end point.
Classification
• On the basis of the type of reaction:
Acid- Base titration ( Acidimetry or Alkalimetry)
Precipitation titration
Complexometric titration
Oxidation- reduction titration
Terms
• Standard Solution
The strength of solution is expressed by
i) Molarity
ii) Normality
iii) Molality
iv) Mole fraction
v) Percentage.
Calculation of Equivalent weight
• Equivalent Weight of an Acid
Basicity of an acid
• Equivalent Weight of a base
Acidity of a base
• Equivalent of a salt
• Equivalent Weight of an Oxidizing agent
• Equivalent Weight of a Reducing agent
Preparation of Standard Solutions
• Weigh definite quantity of Pure Substance.
Dissolve in suitable solvent.
Dilute and prepare required strength.
V1M1=V2M2
Pure substances:
e.g. Sodium carbonate, Potassium hydrogen phthalate, benzoic
acid, Sodium tetraborate, Silver nitrate, Sodium chloride, Potassium
chloride, Potassium dichromate etc.
Secondary standards-indirect method.
Primary & Secondary Standards
• Conditions to be satisfied by Primary
standard.
Must be easy to get in pure form, to dry and preserve in pure state.
Must be unaltered in air ( must not be hygroscopic, efflorescent or
Deliquescent and also not affected by Oxygen or Carbon dioxide)
Impurities should not exceed 0.01 to 0.02% and should be able to be
analyzed.
High relative molecular mass for the compound. Error in weighing
should not effect the accuracy of the strength of solution
Substance should be readily soluble.
Reaction must be stoichiometrically valid and fast