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Module 8: Applying Chemical Ideas
Quick questions on Infrared spectroscopy of organic compounds explained: HSC Chemistry Module 8
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are strengths?Show answer
Fast (seconds per spectrum on a modern FTIR), non-destructive (the sample can be recovered), identifies functional groups directly, and works on solids, liquids and gases.
What are limits?Show answer
Does not give exact carbon counts (use mass spectrometry). Cannot distinguish enantiomers (use chiral chromatography or polarimetry). Heavily overlapping peaks in the fingerprint region need a reference library to resolve.
What is q1?Show answer
State the wavenumber ranges associated with each of: O-H of an alcohol, O-H of a carboxylic acid, C=O of a carbonyl. [3 marks]
What is q2?Show answer
A compound has molecular formula and shows a sharp strong absorption at 1720 cm but no absorption above 3000 cm. Calculate the degree of unsaturation and identify the compound. [3 marks]
What is q3?Show answer
A student records IR spectra of three unknowns X, Y, Z. X shows broad O-H at 3300, no C=O. Y shows sharp C=O at 1720, no O-H.
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