[Bysons]

An unknown gas, X2(g), which behaves much like N2(g), is analysed and the following enthalpies of formation are obtained;

Gas         delta(Hf)


X(g)        401 kJ/mol


H(g)        216 kJ/mol


X2H4(g)     413 kJ/mol



We also know that the X-H bond energy is 284 kJ/mol. Use this information to estimate the X-X single-bond energy. (ans in kJ/mol.)

Not sure how to figure this out.

[sjb]

An unknown gas, X₂(g), which behaves much like N₂(g), is analysed and the following enthalpies of formation are obtained;

Gas         delta(Hf)


X(g)        401 kJ/mol


H(g)        216 kJ/mol


X₂H₄(g)     413 kJ/mol



We also know that the X-H bond energy is 284 kJ/mol. Use this information to estimate the X-X single-bond energy. (ans in kJ/mol.)

Not sure how to figure this out.

Can you write out a Hess' law cycle for the proposed reaction?