Virtual Labs

Electronic spectra of conjugated dye and test of free electron model

In a particle-in-a-box model the energy levels

a: are equally spaced Explanation

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b: are proportional to the box length Explanation

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c: are inversely proportional to the square of the box length Explanation

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d: Have random values Explanation

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Which of the following statements is true about the electronic spectra of conjugated dyes?

a: The position of the absorption bands is not affected by the length of the conjugated system Explanation

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b: The intensity of the absorption bands is not affected by the concentration of the dye in solution. Explanation

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c: The electronic spectra cannot be used to determine the concentration of the dye in solution Explanation

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d: The molar extinction coefficient can be calculated from the electronic spectra Explanation

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Which of the following statements is true about the electronic spectra of conjugated dyes?

a: The n-π* transition always occurs at a lower energy than the π-π* transitioner1 Explanation

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b: The π-π* transition always occurs at a lower energy than the n-π* transition. Explanation

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c: The energy difference between the π-π* and n-π* transitions is always constant irrespective of the molecule Explanation

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d: The σ - σ* transition always occurs at a lower energy than the π -π* transition Explanation

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In the Free Electron Model, what is the effect of increasing the number of electrons in the conjugated system?

a: The absorption bands shift to shorter wavelengths. Explanation

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b: The absorption bands shift to longer wavelengths. Explanation

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c: The absorption bands will not change. Explanation

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d: More vibrational fine structure will appear in the absorption band. Explanation

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What is the general trend observed in the electronic spectra of conjugated dyes as the length of the conjugated system increases?

a: The absorption bands shift to shorter wavelengths Explanation

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b: The absorption bands shift to longer wavelengths Explanation

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c: More vibrational fine structure will appear in the absorption band Explanation

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d: The intensity of the absorption bands decreases Explanation

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