The bond energy of 1 mole of C=C is 620kJ ==> the bond energy of 1 particle of C=C = 620/(6.02*10^23) = 1.03*10^(-21)kJ = 1.03*10^(-18)J= 2B ==> B = 5.15*10^(-19)J Maximum wavelength are in nanometer, so I think we need to convert it to meter; this value of B would make sense. I hope this is correct.

-- Anonymous, March 28, 2000