Chromophores and Absorption of Light Quiz
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Chromophores and Absorption of Light Quiz

Created by
@DeftPluto

Questions and Answers

Which of the following compounds is an example of a compound with sufficient conjugation that absorbs in the visible region?

β-carotene

What effect does the length of the conjugated system generally have on the values of λmax?

It increases the values of λmax

What is an auxochrome?

A group that increases the value of λmax by extending the conjugation through resonance

Which of the following is NOT an example of an auxochrome group?

<p>CO2</p> Signup and view all the answers

What is the general effect of bathochromic groups on wavelength?

<p>They cause a red shift</p> Signup and view all the answers

What does ΔE = hν= hc/λ represent?

<p>The relationship between energy, frequency, and wavelength</p> Signup and view all the answers

What type of transitions do chromophores with both π and non-bonding electrons undergo?

<p>π → π* and n → π* transitions</p> Signup and view all the answers

What is the role of chromophores in relation to the color of compounds?

<p>They increase the ability to absorb radiation</p> Signup and view all the answers

What happens to the absorption maximum when two or more conjugated chromophore groups are present?

<p>It is shifted to a longer wavelength</p> Signup and view all the answers

Which compound shows a lower energy transition, 1,3-butadiene or ethylene?

<p>1,3-butadiene</p> Signup and view all the answers

What type of molecular orbitals are formed in conjugated dienes, from the separate alkene groups?

<p>2 bonding molecular orbitals and 2 antibonding molecular orbitals</p> Signup and view all the answers

Which compound shows a higher absorption maximum, ethylene or 1,3-butadiene?

<p>1,3-butadiene</p> Signup and view all the answers

Study Notes

Conjugation and Absorption

  • Compounds with sufficient conjugation absorb in the visible region.
  • The length of the conjugated system generally increases the values of λmax.

Auxochrome Groups

  • An auxochrome is a group that increases the intensity of color by extending the conjugation of a chromophore.
  • The -OH group is not an example of an auxochrome group.

Bathochromic Groups

  • Bathochromic groups shift the absorption maximum to a longer wavelength.

Energy Transitions

  • ΔE = hν = hc/λ represents the energy of a transition.

Chromophores and Transitions

  • Chromophores with both π and non-bonding electrons undergo n → π* and π → π* transitions.
  • The role of chromophores is to determine the color of compounds by absorbing specific wavelengths of light.

Multiple Chromophore Groups

  • When two or more conjugated chromophore groups are present, the absorption maximum increases.

Comparing Compounds

  • 1,3-butadiene shows a lower energy transition than ethylene.
  • 1,3-butadiene shows a higher absorption maximum than ethylene.

Molecular Orbitals

  • In conjugated dienes, separate alkene groups form molecular orbitals that are delocalized and extended.

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Description

Test your knowledge on chromophores and their role in the absorption of light. Explore the factors affecting the wavelength and intensity of absorption in compounds containing chromophores.

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