Question

For h2o2(g), find the value of δh∘f. (use appendix c in the textbook.)

Answer 1

Delta H equals : -136.10 kj

Answer 2

Answer : - 136.0 KJ/mol

Explanation : The complete question is attached below; assuming that the bond energies are given as per the question to find out the heat of formation of
`H_(2)O_(2)_((g))` we need to draw its lewis dot structure for this reaction;

`H_(2)_((g)) + O_(2)_((g)) ----> H_(2)O_(2)_((g))`

`H_(2)` will have H-H bond and
`O_(2)` will have O=O with 2 pairs of lone electrons on each of O atom.....These are the bonds which are broken

In
`H_(2)O_(2)_((g))` has H-O-O-H bonds; Here, O atom again has 2 pairs of lone pairs on each O atom; ....These are bonds which are made

ΔH°f = ∑ {ΔH(bonds broken) - ΔH (bonds made)}

ΔH°f = ∑ { (432 + 494) - [(459 X 2) +142] }

On solving, We get,

ΔH°f = -136.0 KJ/mol

Hence, the heat of formation for
`H_(2)O_(2)_((g))` will be -136.0 KJ/mol