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The dissociation energy of H2 is 430.53 KJ/mol. If H2 is exposed to radiant energy of wavelength 253.7 nm, what % of radiant energy will be converted into KE?

The dissociation energy of H2 is 430.53 KJ/mol. If H2 is exposed to radiant energy of wavelength 253.7 nm, what % of radiant energy will be converted into KE?

Grade:11

1 Answers

Ramesh V
70 Points
15 years ago

The bond dissociation energy for the H-H bond is the energy required to break the H2 molecule (in its most stable geometry) into separate hydrogen atoms.

Radiant energy = 1242 eV-nm / 253.7 nm = 4.895 eV = 7.843x10-19 J

1 mole of electrons is 6.022 x 1023 electrons

so radiant energy = 472.28 KJ/mol

dissoc. energy     = 430.53 KJ/mol

KE = rad. enrgy - dissoc. energy

      = 472.28 - 430.53

      =41.75 KJ/mol

% of rad. enrgy to KE is = 41.75*100/472.28

                                           = 8.84 %

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