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4 Cards in this Set
- Front
- Back
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(a) understand the terms.. Relative atomic mass, Relative isotopic mass, Relative molecular mass, Molar mass based on the C-12 scale and of the Avogadros constant . And define the mole in terms of the C-12 isotope. |
Relative atomic mass Average mass of 1 atom of an element relative to 1/12th the mass of 1 atom of Carbon-12 Relative isotopic mass Mass of an 1 isotope relative to 1/12th the mass of 1 atom of Carbon-12 |
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(b) Mass spectrometry |
(1) gaseous sample into ionisation chamber
(2) beam of electrons fired from heated filament. Collides with sample and ionises it into a cation.
(3) accelerating negative plates accelerate cation.
(4) cation deflected by electromagnet dependant upon the mass/charge ratio (m/z)
(5) sample detected .
NB- must be free of air because: (1) sample will collide with air particles and slow down acceleration. (2) air can be detected and affect the spectrum results. |
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(b) Mass spectrum of the Chlorine molecule |
Chlorine naturally exist as a diatomic molecule. Means on a mass spectrum, there will be a spectrum at 35 and 37 but also: 70 (35+35) 72 (35+37) 74 (37+37) |
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(c) empirical formulae |
The simplest whole number ratio of the elements in a compound. |
