Problem: Suppose you have two unlabeled flasks, and each flask contains one of these two compounds:Can you differentiate the compounds using a UV spectrophotometer? Select the true statement.a. The λmax of the compound with 2 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 3 conjugated bonds. b. The λmax of the compound with 3 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 2 conjugated bonds.c. The two compounds cannot be differentiated by their λmax values.

FREE Expert Solution

Conjugated dienes are chromophores which contribute colors to a compound by light absorption.

The greater the conjugation and resonance, the longer the wavelength absorbed by the compound.

When electrons absorb energy, they transition from a lower energy orbital to a higher energy orbital.

Highest Occupied Molecular Orbital (HOMO) → Lowest Unoccupied Molecular Orbital (LUMO)


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Problem Details

Suppose you have two unlabeled flasks, and each flask contains one of these two compounds:

Can you differentiate the compounds using a UV spectrophotometer? Select the true statement.

a. The λmax of the compound with 2 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 3 conjugated bonds. 

b. The λmax of the compound with 3 conjugated bonds appears at a longer wavelength than does the λmax of the compound with 2 conjugated bonds.

c. The two compounds cannot be differentiated by their λmax values.

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