Question

For a specific molecule, the energy difference between the HOMO and LUMO is 2.50 eV. What wavelength (in nm) will there be a maximum absorbance? Do not include units in the answer and report to three significant figures.

Answer 1

Answer:

The wavelength at which maximum absorbance will be seen is 496.6 nm.

Explanation:

The energy difference between the HOMO and LUMO =E = 2.50 eV

The wavelength at which maximum absorbance will be observed is related to energy of the difference of the HOMO and LUMO.

$E=\frac{hc}{\lambda }$

E = energy of photon of related to wavelength

h = Planck's constant = $6.63\times 10^{-34}Js$

c = speed of light = $3\times 10^8m/s$

$\lambda$ = wavelength = ?

E = 2.50 eV = $=2.50\times 1.60218\times 10^{-19} J=4.0054 \times 10^{-19} J$

$\lambda =\frac{6.63\times 10^{-34}Js\times 3\times 10^8 m/s}{4.0054 \times 10^{-19} J}=4.966\times 10^{-7} m$

$\lambda =496.6 nm (1 m = 10^9 nm)$

The wavelength at which maximum absorbance will be seen is 496.6 nm.