Notes Unit I_A.
Q 1) Define Qualitative Analysis.
Answer: Qualitative analysis refers to analyses in which substances are identified or classified on the
basis of their chemical or physical properties like chemical reactivity, melting point, solubility, radiative properties (emission, absorption), nuclear half-time, mass spectra.
Q 2) Define Quantitative Analysis.
Answer: Quantitative analysis refers to analyses in which amount or concentration of the analyte may be determined (estimated) and expressed as numeric value in appropriate units.
P.S. Qualitative analysis may take place with quantitative analysis, but quantitative analysis requires
identification or qualification of the analytes for which numerical estimates are given.
1. Analytical methods are classified being either classical or instrumental.
2. Classical methods are sometimes called wet-chemical methods preceded instrumental methods by a century or more.
3.Classical Methods. Separating components of interest from a sample: Precipitation, Extraction,
Distillation.
Qualitative Analysis : Qualitative analysis is performed treating separated
component by reagent which yielded products which
could be recognized from their colour, their boiling or
melting points, solubilities in a series of solvents,their optical activities or refractive indexes.
Quantitative Analysis:The amount of the analyte was determined by gravimetric or volumetric measurements.
In gravimetric measurements, the mass of the analyte or some product produced from the analyte is measured
In volumetric measurements, the volume or mass of a standard reagent required to react completely with analyte is measured.
4.Instrumental Methods. Separation:1) Chromatography
2) Electrophoresis
In early twentieth century, scientists began to exploit phenomena other than those encountered in classical methods, like conductivity, electrode potential, light absorption or emission, mass-to- charge ratio ,for quantitative analysis.
Advantages of Instrumental Methods over classical methods
1.Time Saving: Analysis time has been reduced from several hours or days to even minutes.
2.Improvement in the accuracy of results by elimination of errors due to personal bias.
3.Improvement in sensitivity leading to trace analysis at ppt or even femto-mole levels.Such sensitivities could not be imagined using the conventional classical approach.
4.Fast decisions in case of online analysis during manufacturing operations or deciding on validity before taking commercial decisions.
Various Units used in Chemical Analysis.
1. Radiometry : Radiometry is a set of techniques for measuring electromagnetic radiation including
visible light. Radiometric techniques characterize the distribution of radiation power in space.
Quantity Unit Notes
Radiant Energy Joule Energy of electromagnetic radiation
Radiant Energy Density Joule per cubic metre Radiant Energy per unit volume
Radiant Flux Watt Radiant energy transmitted, reflected,
emitted, received per unit time.
Spectral Flux Watt per Hertz Radiant Flux per unit frequency or wavelength.
2.Photometry: Photometry is the science of measurement of light, in terms of its perceived brightness
to the human eye.
Quantity Unit Notes
Luminous Energy Lumen Second The Lumen Second is sometimes called
talbot.
Luminous Flux Lumen Luminous energy per unit time.
Luminous Intensity Candela Luminous flux per unit solid angle.
Luminance Candela per square metre Luminous flux per unit solid angle per unit projected area.
Q 1) Define Qualitative Analysis.
Answer: Qualitative analysis refers to analyses in which substances are identified or classified on the
basis of their chemical or physical properties like chemical reactivity, melting point, solubility, radiative properties (emission, absorption), nuclear half-time, mass spectra.
Q 2) Define Quantitative Analysis.
Answer: Quantitative analysis refers to analyses in which amount or concentration of the analyte may be determined (estimated) and expressed as numeric value in appropriate units.
P.S. Qualitative analysis may take place with quantitative analysis, but quantitative analysis requires
identification or qualification of the analytes for which numerical estimates are given.
1. Analytical methods are classified being either classical or instrumental.
2. Classical methods are sometimes called wet-chemical methods preceded instrumental methods by a century or more.
3.Classical Methods. Separating components of interest from a sample: Precipitation, Extraction,
Distillation.
Qualitative Analysis : Qualitative analysis is performed treating separated
component by reagent which yielded products which
could be recognized from their colour, their boiling or
melting points, solubilities in a series of solvents,their optical activities or refractive indexes.
Quantitative Analysis:The amount of the analyte was determined by gravimetric or volumetric measurements.
In gravimetric measurements, the mass of the analyte or some product produced from the analyte is measured
In volumetric measurements, the volume or mass of a standard reagent required to react completely with analyte is measured.
4.Instrumental Methods. Separation:1) Chromatography
2) Electrophoresis
In early twentieth century, scientists began to exploit phenomena other than those encountered in classical methods, like conductivity, electrode potential, light absorption or emission, mass-to- charge ratio ,for quantitative analysis.
Advantages of Instrumental Methods over classical methods
1.Time Saving: Analysis time has been reduced from several hours or days to even minutes.
2.Improvement in the accuracy of results by elimination of errors due to personal bias.
3.Improvement in sensitivity leading to trace analysis at ppt or even femto-mole levels.Such sensitivities could not be imagined using the conventional classical approach.
4.Fast decisions in case of online analysis during manufacturing operations or deciding on validity before taking commercial decisions.
Various Units used in Chemical Analysis.
1. Radiometry : Radiometry is a set of techniques for measuring electromagnetic radiation including
visible light. Radiometric techniques characterize the distribution of radiation power in space.
Quantity Unit Notes
Radiant Energy Joule Energy of electromagnetic radiation
Radiant Energy Density Joule per cubic metre Radiant Energy per unit volume
Radiant Flux Watt Radiant energy transmitted, reflected,
emitted, received per unit time.
Spectral Flux Watt per Hertz Radiant Flux per unit frequency or wavelength.
2.Photometry: Photometry is the science of measurement of light, in terms of its perceived brightness
to the human eye.
Quantity Unit Notes
Luminous Energy Lumen Second The Lumen Second is sometimes called
talbot.
Luminous Flux Lumen Luminous energy per unit time.
Luminous Intensity Candela Luminous flux per unit solid angle.
Luminance Candela per square metre Luminous flux per unit solid angle per unit projected area.
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