Question

How do you determine the heat of formation of hydrogen peroxide from the given bond energies: `H_2(g) + O_2(g) -> H_2O_2(g)`? Bond energies: H-H = 432; O2 = 494, O-H = 459. O-O = 142?

Answer 1

See below

Explanation:

I'd maybe draw out the lewis structure for the reacting species, this is important in figuring the `DeltaH_(Rx)` so that we know exactly how many of each bond is being broken and how many of each bond has formed through one mol of the reaction about the chemical system.

For the `DeltaH_(Rx)` for `H_2(g)+O_2(g)=>H_2O_2(g)`, see the graphic below:

The specific energies are shown in parenthesis.