Question

Molecules have ionization energies, just like atoms do. The ionization energy for molecular oxygen, for example, is 1314 kJ/mol. This is the amount of energy required to remove one electron from an O2 molecule, forming an O2+ ion. What is the longest wavelength of light that could ionize an O2 molecule?

Answer 1

Answer:

91.1835 nm

Explanation:

Given that the ionization energy of the oxygen molecule = 1314 kJ/mol

It means that

1 mole of oxygen molecules can be ionized by the energy = 1314 kJ = 1314000 J

1 mole of molecules contains 6.022 × 10²³ atoms

So,

6.022 × 10²³ atoms of oxygen molecules can be ionized by the energy = 1314000 J

1 atom require $\frac{1314000}{6.022\times 10^{23}}\ J$ of energy

Energy = $2.18\times 10^{-18}\ J$

Also

$E=\frac {h\times c}{\lambda}$

Where,  

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

$\lambda$ is the wavelength

So,

$\lambda=\frac {h\times c}{E}$

$\lambda=\frac{6.626\times 10^{-34}\times 3\times 10^8}{2.18\times 10^{-18}}\ m$

$\lambda=91.1835\times 10^{-9}}\ m$

Also,

$1\ nm=10^{-9}}\ m$

So, wavelength = 91.1835 nm