Question

Calculate the wavelength of the radiation which would cause the photodissocitaion of chlorine molecule if the $Cl-Cl$ bond energy is $243kJ$ ${mol}^{-1}$.

Answer 1

$Cl-Cl$ bond energy is 243KJ/mol=$243000J/mol$

Hence,the energy required to dissociate$Cl-Cl$ bond in a chlorine molecule

$\frac{243000J{mol}^{-1}}{6.022\times {10}^{23}{mol}^{-1}}$

$=4\times {10}^{-19}J$

Since,$\frac{hc}{\lambda }$

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

Hence,

$6.626\times {10}^{-34}\times 3\times {10}^{\frac{-8}{4}}\times {10}^{-19}$

$4.97\times {10}^{-7}m$

$497nm$