A researcher records three distinct absorption peaks for an unknown gaseous molecule
CHEMISTRY · Multi-part · A Level · Chemistry · Organic analysis and spectroscopy · Organic analysis and spectroscopy
Problem
A researcher records three distinct absorption peaks for an unknown gaseous molecule. The measured peak positions are listed below.
• Peak I: 3.20 mm
• Peak II: 4.50 µm
• Peak III: 250 nm
Answer the following questions based on these data. Use the usual physical constants that appear on the AP Chemistry reference tables.
(1) For each peak, identify the region of the electromagnetic spectrum in which it lies.
(2) For each peak, state the type of molecular transition (rotational, vibrational, or electronic) that is most plausibly responsible for the absorption and describe, in one or two sentences, the physical meaning of that transition.
(3) Without performing a numerical computation, order the three photons associated with Peaks I–III from lowest energy to highest energy and justify your ranking qualitatively.