http://lawrencekok.blogspot.com

Prepared by Lawrence Kok

Tutorial on Analytical Chemistry, Spectroscopy and Line Emission Spectrum

Study on Identification, Structural Determination, Quantification and Separation Involves Qualitative and Quantitative analysis• Quantitative analysis – Amount present in a sample/mixture• Qualitative analysis – What is present/Identity of species in a impure sample/mixture?• Structural analysis – Determination of structure of a molecule• Separation of mixtures – Chromatographic Techniques• Identification of molecules / functional groups• Purity of substances• Composition in a mixture

Analytical Chemistry

Classical method

Analytical Techniques

Qualitative analysis Quatitative analysis

Flame testChemical test

Gravimetric Volumetric Titration

Separation analysis

Melting/boiling point

Precipitation

http://www.glogster.com/joealba/flame-test-lab-post-lab-report/g-6m0d3jrphfhikt976ce4ia0/http://www.chemcollective.org/chem/ubc/exp01

Distillation

Analytical Techniques

Classical method

Instrumental method

Analytical Techniques

Classical method

Qualitative analysis

Quatitative analysis

Instrumental method

Spectroscopy analysis

Separation analysis

Analytical Techniques

Classical method

Qualitative analysis

Quatitative analysis

Chemical test

Flame test

Volumetric Titration

Gravimetric

Instrumental method

Spectroscopy analysis

Separation analysis

Nuclear Magnetic Resonance Spectroscopy

Atomic Absorption Spectroscopy

Ultra Violet Spectroscopy

Atomic Emission Spectroscopy

Infra Red Spectroscopy

Mass Spectroscopy

Paper Chromatography

High Performance Liquid ChromatographyGas Liquid Chromatography

Column Chromatography

Thin Layer Chromatography

• Spectroscopy measures the interaction of the molecules with electromagnetic radiation• Particles (molecule, ion, atom) can interact/absorb a quantum of light

Picture from: http://www.lpi.usra.edu/education/fieldtrips/2005/activities/ir_spectrum/

Spectroscopy

Electromagnetic Radiation

• Spectroscopy measures the interaction of the molecules with electromagnetic radiation• Particles (molecule, ion, atom) can interact/absorb a quantum of light

Picture from: http://www.lpi.usra.edu/education/fieldtrips/2005/activities/ir_spectrum/

Spectroscopy

Electromagnetic Radiation

High Energy Radiation

Gamma/X ray

UV or visible Infra Red Microwave Radiowaves

Low Energy Radiation

• Spectroscopy measures the interaction of the molecules with electromagnetic radiation• Particles (molecule, ion, atom) can interact/absorb a quantum of light

Picture from: http://www.lpi.usra.edu/education/fieldtrips/2005/activities/ir_spectrum/

Spectroscopy

Electromagnetic Radiation

Nuclear spin

High Energy Radiation

Gamma/X ray

Transition of inner electrons

UV or visible

Transition of outer most valence electrons

Infra Red

Molecular vibration

Microwave

Molecular rotation

Radiowaves

Low Energy Radiation

Infra Red Spectroscopy

Nuclear Magnetic Resonance Spectroscopy

Ultra Violet Spectroscopy

Atomic Absorption Spectroscopy

Velocity of light (c ) = frequency (f) x wavelength (λ)• c = f λ• All electromagnetic waves travel at the speed of light (3.00 x 108ms-1)• Radiation with high ↑ frequency – short ↓ wavelength• Electromagnetic radiation has a particle nature and each photon carry a quantum of energy given by

h = plank constant = 6.626 x 10-34 Js c = speed of light = 3.00 x 108ms-1

f = frequency λ = wavelength

hc

E Short ↓ λ, Higher ↑ frequency, Higher Energy ↑

E = hf

Electromagnetic Radiation

Picture from :http://www.azimuthproject.org/azimuth/show/Blog+-+a+quantum+of+warmth

Electromagnetic Radiation and Spectroscopy

Radiowaves Infra Red UV or visible

Electromagnetic Radiation

Electromagnetic Radiation Interact with Matter (Atoms, Molecules) = Spectroscopy

Electromagnetic Radiation and Spectroscopy

Radiowaves

Nuclear spin

Nuclear Magnetic Resonance Spectroscopy

Infra Red

Molecular vibration

Infra Red Spectroscopy

UV or visible

Transition of outer most valence electrons

Electromagnetic Radiation

UV Spectroscopy

Atomic Absorption Spectroscopy

Electromagnetic Radiation Interact with Matter (Atoms, Molecules) = Spectroscopy

Electromagnetic Radiation and Spectroscopy

Radiowaves

Nuclear spin

Nuclear Magnetic Resonance Spectroscopy

• Organic structure determination

• MRI and body scanning

Infra Red

Molecular vibration

Infra Red Spectroscopy

UV or visible

Transition of outer most valence electrons

• Organic structure determination

• Functional gp determination• Measuring bond strength• Measuring degree

unsaturation in fat• Measuring level of alcohol in

breath

Electromagnetic Radiation

UV Spectroscopy

Atomic Absorption Spectroscopy

• Quantification of metal ions• Detection of metal in various

samples

Electromagnetic Radiation Interact with Matter (Atoms, Molecules) = Spectroscopy

http://www.astrophys-assist.com/educate/orion/orion02.htm

Continuous Spectrum :Light spectrum with all wavelength/frequency

Emission Line Spectrum :• Spectrum with discrete wavelength/ frequency • Emitted when excited electrons drop from higher to

lower energy level Absorption Line Spectrum :• Spectrum with discrete wavelength/frequency • Absorbed when ground state electrons are excited

Continuous Spectrum Vs Line Spectrum

http://www.astrophys-assist.com/educate/orion/orion02.htm

Continuous Spectrum :Light spectrum with all wavelength/frequency

Emission Line Spectrum :• Spectrum with discrete wavelength/ frequency • Emitted when excited electrons drop from higher to

lower energy level Absorption Line Spectrum :• Spectrum with discrete wavelength/frequency • Absorbed when ground state electrons are excited

Atomic Emission Spectroscopy

Ground state

Excited stateElectrons from excited state

Emit radiation when drop to ground state

Radiation emitted

Emission Spectrum

Continuous Spectrum Vs Line Spectrum

http://www.astrophys-assist.com/educate/orion/orion02.htm

Continuous Spectrum :Light spectrum with all wavelength/frequency

Emission Line Spectrum :• Spectrum with discrete wavelength/ frequency • Emitted when excited electrons drop from higher to

lower energy level Absorption Line Spectrum :• Spectrum with discrete wavelength/frequency • Absorbed when ground state electrons are excited

Atomic Emission Spectroscopy Vs Atomic Absorption Spectroscopy

Ground state

Excited stateElectrons from excited state

Emit radiation when drop to ground state

Radiation emitted

Emission Spectrum

Electrons from ground state

Absorb radiationto excited state

Electrons in excited state

Radiation absorbed

Continuous Spectrum Vs Line Spectrum

Line Emission Spectra for Hydrogen

Energy supplied to atoms • Electrons are excited from ground to excited states• Electrons exist in fixed energy level (quantum)• Electrons drop from higher to lower, emitting energy of particular wavelength/frequency• Higher the energy level, smaller the difference in energy between successive energy level.• Spectrum will converge(get closer) with increasing frequency• Lines in spectrum converge- energy levels also converge• Ionisation energy can be determined (Limit of convergence)

Atomic Emission Spectroscopy

UV regionLyman Series n=∞ → n= 1

Visible regionBalmer Series n=∞ → n= 2

IR regionPaschen Series n=∞ → n= 3

Line Emission Spectra for Hydrogen

Energy supplied to atoms • Electrons are excited from ground to excited states• Electrons exist in fixed energy level (quantum)• Electrons drop from higher to lower, emitting energy of particular wavelength/frequency• Higher the energy level, smaller the difference in energy between successive energy level.• Spectrum will converge(get closer) with increasing frequency• Lines in spectrum converge- energy levels also converge• Ionisation energy can be determined (Limit of convergence)

Atomic Emission Spectroscopy

UV regionLyman Series n=∞ → n= 1

Visible regionBalmer Series n=∞ → n= 2

IR regionPaschen Series n=∞ → n= 3

Line Emission Spectra for Hydrogen

Energy supplied to atoms • Electrons are excited from ground to excited states• Electrons exist in fixed energy level (quantum)• Electrons drop from higher to lower, emitting energy of particular wavelength/frequency• Higher the energy level, smaller the difference in energy between successive energy level.• Spectrum will converge(get closer) with increasing frequency• Lines in spectrum converge- energy levels also converge• Ionisation energy can be determined (Limit of convergence)

N = 3-2, 656nm

N= 4-2486nm

N= 5-2434nm

N= 6-2410nm

Atomic Emission Spectroscopy

Visible region- Balmer Series

UV regionLyman Series n=∞ → n= 1

Visible regionBalmer Series n=∞ → n= 2

IR regionPaschen Series n=∞ → n= 3

Atomic Emission Spectra• Energy supplied• Electrons surround nucleus in allowed energy states (quantum)• Excited electron returning to lower energy level, photon of light with discrete energy/wavelength(colour) will be given out.• Light pass through a spectroscope, with a prism to separate out different colours• Line emission spectra is produced.

Line emission spectra for different elements can be found here

Acknowledgements

Thanks to source of pictures and video used in this presentation

Thanks to Creative Commons for excellent contribution on licenseshttp://creativecommons.org/licenses/

Prepared by Lawrence Kok

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