Reactivity 1.2.1—Bond-breaking absorbs and bond-forming releases energy. Calculate the enthalpy change of a reaction from given average bond enthalpy data.

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Methane undergoes incomplete combustion.

2CH₄ (g) + 3O₂ (g) → 2CO (g) + 4H₂O (g)

What is the enthalpy change, in kJ, using the bond enthalpy data given below?

A. [2(1077) + 4(463)] − [2(414) + 3(498)]

B. [2(414) + 3(498)] − [2(1077) + 4(463)]

C. [8(414) + 3(498)] − [2(1077) + 8(463)]

D. [2(1077) + 8(463)] − [8(414) + 3(498)]

Which equation represents the N–H bond enthalpy in NH₃?

A.  NH₃ (g) → N (g) + 3H (g)

B.  $\frac{1}{3}$NH₃ (g) → $\frac{1}{3}$N (g) + H (g)

C.  NH₃ (g) → $\frac{1}{2}$N₂ (g) + $\frac{3}{2}$H₂ (g)

D.  NH₃ (g) → •NH₂ (g) + •H (g)

Which equation represents the N–H bond enthalpy in NH₃?

A.  NH₃ (g) → N (g) + 3H (g)

B.  $\frac{1}{3}$NH₃ (g) → $\frac{1}{3}$N (g) + H (g)

C.  NH₃ (g) → $\frac{1}{2}$N₂ (g) + $\frac{3}{2}$H₂ (g)

D.  NH₃ (g) → •NH₂ (g) + •H (g)

Which equation represents the N–H bond enthalpy in NH₃?

A.  NH₃ (g) → N (g) + 3H (g)

B.  $\frac{1}{3}$NH₃ (g) → $\frac{1}{3}$N (g) + H (g)

C.  NH₃ (g) → $\frac{1}{2}$N₂ (g) + $\frac{3}{2}$H₂ (g)

D.  NH₃ (g) → •NH₂ (g) + •H (g)

Which equation represents the N–H bond enthalpy in NH₃?

A.  NH₃ (g) → N (g) + 3H (g)

B.  $\frac{1}{3}$NH₃ (g) → $\frac{1}{3}$N (g) + H (g)

C.  NH₃ (g) → $\frac{1}{2}$N₂ (g) + $\frac{3}{2}$H₂ (g)

D.  NH₃ (g) → •NH₂ (g) + •H (g)

What is the $\mathrm{H}-\mathrm{H}$ bond enthalpy, in $\mathrm{kJ} {\mathrm{mol}}^{-1}$, in the ${\mathrm{H}}_2$ molecule?

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$∆H_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=x \mathrm{kJ} {\mathrm{mol}}^{-1}$

A.  $x-y+4z$

B.  $\frac{1}{2}\left(x-y+4z\right)$

C.  $x-y+2z$

D.  $\frac{1}{2}\left(x-y+2z\right)$

What is the $\mathrm{H}-\mathrm{H}$ bond enthalpy, in $\mathrm{kJ} {\mathrm{mol}}^{-1}$, in the ${\mathrm{H}}_2$ molecule?

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$∆H_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=x \mathrm{kJ} {\mathrm{mol}}^{-1}$

A.  $x-y+4z$

B.  $\frac{1}{2}\left(x-y+4z\right)$

C.  $x-y+2z$

D.  $\frac{1}{2}\left(x-y+2z\right)$

What is the $\mathrm{H}-\mathrm{H}$ bond enthalpy, in $\mathrm{kJ} {\mathrm{mol}}^{-1}$, in the ${\mathrm{H}}_2$ molecule?

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$∆H_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=x \mathrm{kJ} {\mathrm{mol}}^{-1}$

A.  $x-y+4z$

B.  $\frac{1}{2}\left(x-y+4z\right)$

C.  $x-y+2z$

D.  $\frac{1}{2}\left(x-y+2z\right)$

What is the $\mathrm{H}-\mathrm{H}$ bond enthalpy, in $\mathrm{kJ} {\mathrm{mol}}^{-1}$, in the ${\mathrm{H}}_2$ molecule?

$2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$∆H_{\mathrm{f}}\left({\mathrm{H}}_2\mathrm{O}\right)=x \mathrm{kJ} {\mathrm{mol}}^{-1}$

A.  $x-y+4z$

B.  $\frac{1}{2}\left(x-y+4z\right)$

C.  $x-y+2z$

D.  $\frac{1}{2}\left(x-y+2z\right)$

Which combustion reaction releases the least energy per mole of C₃H₈?

Approximate bond enthalpy / kJ mol⁻¹
O=O    500
C=O    800
 C≡O   1000

A.  C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O (g)

B.  C₃H₈(g) + $\frac{9}{2}$O₂(g) → 2CO₂(g) + CO (g) + 4H₂O (g)

C.  C₃H₈(g) + 4O₂(g) → CO₂(g) + 2CO (g) + 4H₂O (g)

D.  C₃H₈(g) + $\frac{7}{2}$O₂(g) → 3CO (g) + 4H₂O (g)

Chemistry: Atoms First 2e, https://openstax.org/books/chemistry-atoms-first-2e/pages/9-4-strengths-of-ionic-andcovalent-bonds © 1999–2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License.
(CC BY 4.0) https://creativecommons.org/licenses/ by/4.0/.

Which combustion reaction releases the least energy per mole of C₃H₈?

Approximate bond enthalpy / kJ mol⁻¹
O=O    500
C=O    800
 C≡O   1000

A.  C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O (g)

B.  C₃H₈(g) + $\frac{9}{2}$O₂(g) → 2CO₂(g) + CO (g) + 4H₂O (g)

C.  C₃H₈(g) + 4O₂(g) → CO₂(g) + 2CO (g) + 4H₂O (g)

D.  C₃H₈(g) + $\frac{7}{2}$O₂(g) → 3CO (g) + 4H₂O (g)

Chemistry: Atoms First 2e, https://openstax.org/books/chemistry-atoms-first-2e/pages/9-4-strengths-of-ionic-andcovalent-bonds © 1999–2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License.
(CC BY 4.0) https://creativecommons.org/licenses/ by/4.0/.

Which combustion reaction releases the least energy per mole of C₃H₈?

Approximate bond enthalpy / kJ mol⁻¹
O=O    500
C=O    800
 C≡O   1000

A.  C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O (g)

B.  C₃H₈(g) + $\frac{9}{2}$O₂(g) → 2CO₂(g) + CO (g) + 4H₂O (g)

C.  C₃H₈(g) + 4O₂(g) → CO₂(g) + 2CO (g) + 4H₂O (g)

D.  C₃H₈(g) + $\frac{7}{2}$O₂(g) → 3CO (g) + 4H₂O (g)

Chemistry: Atoms First 2e, https://openstax.org/books/chemistry-atoms-first-2e/pages/9-4-strengths-of-ionic-andcovalent-bonds © 1999–2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License.
(CC BY 4.0) https://creativecommons.org/licenses/ by/4.0/.

Which combustion reaction releases the least energy per mole of C₃H₈?

Approximate bond enthalpy / kJ mol⁻¹
O=O    500
C=O    800
 C≡O   1000

A.  C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O (g)

B.  C₃H₈(g) + $\frac{9}{2}$O₂(g) → 2CO₂(g) + CO (g) + 4H₂O (g)

C.  C₃H₈(g) + 4O₂(g) → CO₂(g) + 2CO (g) + 4H₂O (g)

D.  C₃H₈(g) + $\frac{7}{2}$O₂(g) → 3CO (g) + 4H₂O (g)

Chemistry: Atoms First 2e, https://openstax.org/books/chemistry-atoms-first-2e/pages/9-4-strengths-of-ionic-andcovalent-bonds © 1999–2021, Rice University. Except where otherwise noted, textbooks on this site are licensed under a Creative Commons Attribution 4.0 International License.
(CC BY 4.0) https://creativecommons.org/licenses/ by/4.0/.

Which equation represents the bond enthalpy for H–Br in hydrogen bromide?

A.  HBr (g) → H⁺ (g) + Br⁻ (g)

B.  HBr (g) → H (g) + Br (g)

C.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (l)

D.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (g)

Which equation represents the bond enthalpy for H–Br in hydrogen bromide?

A.  HBr (g) → H⁺ (g) + Br⁻ (g)

B.  HBr (g) → H (g) + Br (g)

C.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (l)

D.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (g)

Which equation represents the bond enthalpy for H–Br in hydrogen bromide?

A.  HBr (g) → H⁺ (g) + Br⁻ (g)

B.  HBr (g) → H (g) + Br (g)

C.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (l)

D.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (g)

Which equation represents the bond enthalpy for H–Br in hydrogen bromide?

A.  HBr (g) → H⁺ (g) + Br⁻ (g)

B.  HBr (g) → H (g) + Br (g)

C.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (l)

D.  HBr (g) → $\frac{1}{2}$H₂ (g) + $\frac{1}{2}$Br₂ (g)

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Outline why the value obtained in (b)(i) might differ from a value calculated using ΔH_f data.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.

Calculate the enthalpy change of the reaction, ΔH, using section 11 of the data booklet.