Chem Question Help

Question

Determine the ΔH of the reaction given the following average bond energies (kJ/mol):

C–O	358
C=O	799
C≡O	1072
C–H	413
H–H	436
O–H	463

Select one:

a.

+735 kJ

b.

+276 kJ

c.

–276 kJ

d.

–116 kJ

Answer 1

ΔH_rxn is approximately Σ_Rn_iE_Bi - Σ_Pn_iE_Bi where R = reactants, P is Products, n_i is the number of moles of that bond (stoichiometry of the species times the number of times the bond appears in that species) in the reaction statement. E_Bi is the bonding energy (The energy to break the bond)

You didn't list the reaction, so I'll just show an example:

CH₄ + 2O₂ ⇒ CO₂ + 2H₂O

4E_B,C-H + 2E_{B, O=O} - 2E_B,C=O + 2(2)E_B,O-H = ΔH