Hydrogen atoms on collision (based on energy conservation)

[george2625]

"Given a simple and violent chemical reaction { H + H → H2 + 5eV }. however when hydrogen atoms collide in free space they simply bounce apart. the reason is that it is impossible to satisfy the laws of conservation of momentum and conservation of energy in a simple 2 body collision which releases energy..."

how can i prove this statement?

 

[voko]

What exactly are you supposed to prove? That H + H = H2 + 5 eV is impossible?

 

[george2625]

we have to prove that it is impossible ... the statement stands for itself,,, the reaction is impossible because of some facts like it don't satisfy the laws of conservation of energy. please help.