Analytical Chemistry Notes
This is a sample of our 11 page long Analytical Chemistry notes, which we sell as part of the IB Chemistry HL Notes collection, a Grade 7 package written at University Of Cambridge in 2012 that contains 57 pages of notes across 8 different documents.
Analytical Chemistry RevisionThe following is a plain text extract of the PDF sample above, taken from our IB Chemistry HL Notes. This text version has had its formatting removed so pay attention to its contents alone rather than its presentation. The version you download will have its original formatting intact and so will be much prettier to look at.
Option A: Modern analytical chemistry A1: Analytical techniques A.1.1 State the reasons for using analytical techniques.
- determination of purity
- structure determination
- composition analysis
- separation of mixtures
- identiﬁcation of substances
- determination of concentration of substance
A.1.2 State that the structure of a compound can be determined by using information from a variety of analytical techniques singularly or in combination.
- combination of analytical techniques used to determine unambiguously the exact structural formula Technique
- presence of organic functional groups
- strength of bonds
- structure & relative atomic masses
- isotropic composition of an element
determine molecular structure (isotopes)
concentration of metal ions in a sample
test for metal ions
A2: Principles of spectroscopy A.2.1 Describe the electromagnetic spectrum. Microwaves!
X-rays ! Gamma Rays
• Wavelength, λ in units of distance is the distance between successive peaks on the wave.
• Frequency, ƒ in units of Hertz is the number of peaks that pass a ﬁxed point every second.
• All electromagnetic spectrum travel at the same speed in a vacuum (c = 3.00 x 108 m s-1) Velocity of light = frequency x wavelength c = λƒ
A.2.2 Distinguish between absorption and emission spectra and how each is produced.
- absorption spectroscopy: continuous spectrum with missing regions corresponding to energies absorbed
- energy is required to move/excite electrons from ground state to excited state
- emission spectroscopy: regions corresponding to energies omitted
- radiation emitted by electrons from excited state (higher energy) → ground state (lower energy level)
A.2.3 Describe the atomic and molecular processes in which absorption of energy takes place.
- the greater the energy difference between the levels, the higher the frequency of the light absorbed
- most energetic absorptions = atomic electronic transitions which involve bond breaking + ionization
A3: Infrared (IR) spectroscopy A.3.1 Describe the operating principles of a double-beam IR spectrometer.
S infrared source: produces light M monochromator: produces a single frequency/wavelength A beam splitter: directs half of the radiation through the sample & the other half to the reference D detector: coverts radiation to an electronic signal; compares the intensities of the sample and reference beams; determines the absorption at particular frequencies Why use a reference?
* prevents ﬂuctuations in the output of the source affecting the data
* cancels the effects of the solvent (reference = pure form of the solvent the sample is in)
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