Question
Crystal field theory predicts that octahedral complexes with six d electrons will be paramagnetic if this energy is large compared to the d orbital splitting energy. For 10 points each:
[10m] Name this energetic penalty imposed on molecules like singlet oxygen that do not follow Hund’s rule.
ANSWER: electron spin pairing energy
[10e] The energy required to pair the spins in oxygen is supplied as light from this region of the electromagnetic spectrum. This radiation produces radicals from diatomic halogens.
ANSWER: ultraviolet light [or UV; accept UV-A or UV-B]
[10h] Since pairing is spin-forbidden, this synthetic thia·zine dye is added as a sensitizer to improve yields of singlet oxygen. Microbiologists combine eosin with this dye to inhibit Gram-positive bacteria, and it is also the redox reporter bonded to gold in most electrochemical sensors.
ANSWER: methylene blue [or MB; or methylthioninium chloride; reject “methylene” or “methyl blue”]
<Chemistry>
Summary
| 2023 ACF Nationals | 04/22/2023 | Y | 1 | 20.00 | 100% | 100% | 0% |
Data
| Georgia Tech A | Chicago A | 10 | 10 | 0 | 20 |