Respuesta :
Answer:
The average bond energy of the sulfur-oxygen bonds in sulfur dioxide is 519.5 kJ/mol.
Explanation:
[tex]SF_4(g) + 2 H_2O(g)\rightarrow SO_2(g) + 4 HF(g) ,[/tex]ΔH = -123 kJ
We are given with:
[tex]\Delta H_{S-F}=327 kJ/mol[/tex]
[tex]\Delta H_{H-F}=565 kJ/mol[/tex]
[tex]\Delta H_{H-O}=467 kJ/mol[/tex]
[tex]\Delta H_{F-F}=154 kJ/mol[/tex]
[tex]\Delta H_{S-O}=?[/tex]
ΔH =
(Energies required to break bonds on reactant side) - (Energies released on formation of bonds on product side)
[tex]\Delta H=(1 mol\times 4\times \Delta H_{S-F}+2 mol\times 2\times \Delta H_{H-O})-(1 mol\times 2\times \Delta H_{S-O}+4 mol\times 1\times\Delta H_{H-F})[/tex]
[tex]\Delta H=(1 mol\times 4\times 327 kJ/mol+2 mol\times 2\times 467 kJ/mol)-(1mol\times 2\times \Delta H_{S-O}+4 mol\times 1\times 565 kJ/mol)[/tex]
[tex]-123 kJ=(1308 kJ+1868kJ)-(1mol\times 2\times \Delta H_{S-O}+2260 kJ)[/tex]
[tex]1mol\times 2\times \Delta H_{S-O}=123 kJ+1308 kJ+1868kJ-2260 kJ[/tex]
[tex]\Delta H_{S-O}=\frac{1039 kJ}{2\times 1 mol}=519.5 kJ/mol[/tex]
The average bond energy of the sulfur-oxygen bonds in sulfur dioxide is 519.5 kJ/mol.
Answer:
520 kJ·mol⁻¹
Explanation:
You calculate the energy required to break all the bonds in the reactants. Then you subtract the energy to break all the bonds in the products.
SF₄(g) + 2H₂O(g) ⟶ SO₂(g) + 4HF(g); ΔH = –123 kJ
Bonds: 4S-F + 4O-H 2S=O 4H-F
D/kJ·mol⁻¹: 327 467 x 565
The formula relating ΔᵣH and bond dissociation energies (D) is
[tex]\Delta _{\text{r}}H = \sum{D_{\text{reactants}} - \sum{D_{\text{products}}[/tex]
(Note: This is an exception to the rule. All other thermochemical reactions are “products – reactants”. With bond energies, it’s “reactants – products”. The reason comes from the way we define bond energies.)
Σ(Dreactants) = 4 × 327 + 4 × 467 = 3176 kJ
Σ(Dproducts) = 2x +4 × 565 = (2x + 2260) kJ
-123 =3176 - (2x + 2260)
-123 = 3176 - 2x - 2260
-123 = 916 - 2x
2x = 1039
x = 520 kJ·mol⁻¹
The average bond energy of the S=O bonds in SO₂ is 520 kJ/mol.
