posted by Kai on .
What energy change is associated with the reaction to obtain one mole of H2 from one mole of water vapor? The balanced equation is 2 H2O(g) -> 2 H2(g) + O2(g)and the relevant bond energies are
H-H : 436 kJ/mol; H-O : 467 kJ/mol;
O-O : 146 kJ/mol; O=O : 498 kJ/mol.
1. +249 kJ
2. −436 kJ
3. +425 kJ
4. −425 kJ
It appears to me that we must break 4 OH bonds for the two moles H2O and form 2 H-H bonds and 2 O-O bonds. The difference between (sum bond energies reactants)-(sum bond energies products) = delta H rxn for 2 moles H2O and 2 moles H2. Therefore, divide that number by 2. Check my thinking.
the answer i -436
lisa that isnt the right answer lol... it is actually -436... stupiddddd