Question

Bond energy of H-H is 103 kcal/mol.
Calculate energy to break one mole of hydrogen.
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Answer 1

Hey,

The question refers to one mole of molecular hydrogen, that is one mole of H2. No of atoms in one mole of hydrogen is:

$6.023 \times 10 {}^{23}$

Therefore the number of bonds will be half as many as this i.e 3.01 x 10^23. (One bond for two atoms)

Energy needed =

$103 \: \frac{kcal}{mol} \times \frac{1}{2} mol \: = 51.5 \: kcal$

You can now convert the answer to joules/calories if needed.