Wavelength from molar dissociation energy

P8.1.3Wavelength from molar dissociation energy

Write a function, get_wv, which takes a molar bond dissociation energy, D0, in $\mathrm{kJ\,mol^{-1}}$ and returns the wavelength of a photon corresponding to that energy per molecule, in nm. The energy of a photon with wavelength $\lambda$ is $E=hc/\lambda$ .

For example,

In [x]: get_wv(497)
Out[x]: 240.69731528286377

Show solution

Here is one way to define get_wv:

wvdissoc

import scipy.constants as pc


def get_wv(D0):
    E = D0 * pc.kilo / pc.N_A  # energy per molecule, J
    lam = pc.h * pc.c / E  # wavelength, m
    return lam / pc.nano  # return wavelength, nm


if __name__ == "__main__":
    D0 = 497
    print(
        f"The wavelength of a photon to dissociate a bond with dissociation"
        f" energy {D0} kJ.mol-1 is {get_wv(D0):.1f} nm."
    )

Output:

    The wavelength of a photon to dissociate a bond with dissociation
    energy 497 kJ.mol-1 is 240.7 nm.