Spectroscopy & Analysis is a core part of A-Level Chemistry. Revise the key concepts and common mistakes below, then lock them in with the free games.
Key concepts
Mass spectrometryFinds relative masses and structure from mass/charge ratios.
Infrared spectroscopyIdentifies bonds and functional groups from absorption peaks.
NMR spectroscopyReveals carbon and hydrogen environments in a molecule.
ChromatographySeparates and identifies components by relative attraction.
FragmentationBreakdown of ions in mass spectrometry, giving structural clues.
Structure determinationCombining techniques to deduce a molecule's structure.
Molecular ion M+Rightmost peak = molecular mass.
M+1 peakFrom 13C isotope; ~1.1% per C.
M+2 peakIndicates Cl (3:1) or Br (1:1).
Base peakTallest peak; normalised to 100%.
TOFTime-of-flight mass spectrometer.
TMSTetramethylsilane reference; delta=0 ppm.
Chemical shift δPosition of NMR signal, ppm.
IntegrationPeak area ~ number of H atoms.
Common mistakes to avoid
Questions where students often pick the tempting wrong answer — make sure you know the right one:
What does mass spectrometry measure?✗ The colour of a compound. ✓ Mass-to-charge ratios, giving relative masses and structural clues.
What does infrared (IR) spectroscopy identify?✗ Exactly how much of a substance is present. ✓ The bonds / functional groups present, from absorption peaks.
Do analytical instruments print a structure with no interpretation?✗ Yes, the machine directly states the structure. ✓ No — spectra (NMR, IR, MS) must be interpreted to deduce structure.
What does a mole of a substance represent?✗ A mole is a unit of mass equal to the relative molecular mass in grams of any substance. ✓ Avogadro's number (6.02 x 10^23) of particles of that substance.
If 50 cm^3 of a 1 mol/dm^3 solution is diluted to 100 cm^3, what is the new concentration?✗ The new concentration is 0.05 mol/dm^3 because you doubled the volume so you halve the concentration once and shift the decimal too. ✓ 0.5 mol/dm^3 — the moles stay the same but the volume doubled.
Practise Spectroscopy & Analysis — free games
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