The absorbance features observed in the visible spectrum for curcumin is a result of an allowed optical excitation of an electron from the π-HOMO to the π*-LUMO. What is the energy change for this electronic excitation based on the spectrum? (Hint: Energy and wavelength are related by the equation E = hc/λ.) h = 4.136 × 10-15 eV⋅ s c = 2.998 × 108 m/s

The energy change for the electronic excitation is :  3.68 * 10⁻¹⁹J

Given data :

h = 4.136 * 10⁻¹⁵ eV⋅ s

c = 2.998 * 108 m/s

λmax = 550 * 10⁻⁹  ( Obtained from image attached below )

Applying the energy and wavelength relationship equation

E = hc / λmax

  = ( 4.136 * 10⁻¹⁵  * 2.998 * 108  ) /   550 * 10⁻⁹

  =  2.3 ev   ≈ 3.68 * 10⁻¹⁹J.

Hence we can conclude that the energy change for the electronic excitation is 2.3 ev   ≈ 3.68 * 10⁻¹⁹J.

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Missing data related to your question is attached below

2.3 ev or 3.68 ×10^-19J

Explanation:

The spectrum is shown in the image attached

h= 4.136 × 10-15 eV⋅ s

c = 2.998 × 108 m/s

λmax= 550×10^-9 (from the spectrum attached)

E=hc/λmax

E= 4.136 × 10^-15 × 2.998 × 10^8/550×10^-9

E= 2.3 ev or 3.68 ×10^-19J