Question

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

Answer 1

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

Answer 2

Delta H equals : -136.10 kj