Question

1. Calculate the delta H for H2(g)+O2(g)=H2O2(g)

Bond energies, kJ x mol^-1
H-H 432
H-O 459
O-O 207
O=O 494

I did:
deltaH=(2(207kJ/mol))-(432kJ/mol+494kJ/mol)
=-512kJ
is that correct?

2. The theoretical effect of an increase in T can be explained in terms of the collision because it affects

a.The fraction of collisions that are effective and the required activation energy for a reaction.

b.The total number of collisions that occur and the required activation energy for a reaction.

I stumped whether the answer is a or b

Answer 1

1. I didn't calculate it but dHrxn = dHreactants + dHproducts.

2. It depends upon the fraction of the molecules that have the required activation energy as well as that constant "A" in the equation so I would go with a.

Answer 2

I thought the equtaion was
dH=[sum of dH of products]-[sum of dH of reactants]?

Answer 3

Your equation is correct if you are dealing with delta Ho BUT you have bond energies. Delta H from bond energies are calculated a different way.