Calculate the enthalpy change, ΔH^⦵, for the Haber–Bosch process, in kJ, using the following data.

$∆H_{ \mathrm{f}}^{⦵}\left({\mathrm{NH}}_3\right)=-46.2 \mathrm{kJ} {\mathrm{mol}}^{-1}$.

Hydrazine reacts with oxygen.

N₂H₄(l) + O₂(g) → N₂(g) + 2H₂O(l)      ΔH^θ = -623 kJ

What is the standard enthalpy of formation of N₂H₄(l) in kJ? The standard enthalpy of formation of H₂O(l) is -286 kJ.

A. -623 - 286
B. -623 + 572
C. -572 + 623
D. -286 + 623

The overall equation for monochlorination of methane is:

CH₄(g) + Cl₂(g) → CH₃Cl(g) + HCl(g)

Calculate the standard enthalpy change for the reaction, ΔH ^θ, using section 12 of the data booklet.

The enthalpy changes for two reactions are given.

Br₂ (l) + F₂ (g) → 2BrF (g)         ΔH = x kJ
Br₂ (l) + 3F₂ (g) → 2BrF₃ (g)      ΔH = y kJ

What is the enthalpy change for the following reaction?

BrF (g) + F₂ (g) → BrF₃ (g)

A.  x – y

B.  –x + y

C.  $\frac{1}{2}$(–x + y)

D.  $\frac{1}{2}$(x – y)

Outline why no value is listed for H₂(g).

What is the enthalpy change of reaction for the following equation?

C₂H₄ (g) + H₂ (g) → C₂H₆ (g)

C₂H₄ (g) + 3O₂ (g) → 2CO₂ (g) + 2H₂O (l)        ΔH = x

C₂H₆ (g) + $\frac{7}{2}$O₂ (g) → 2CO₂ (g) + 3H₂O (l)    ΔH = y

H₂ (g) + $\frac{1}{2}$O₂ (g) → H₂O (l)                           ΔH = z

A. x + y + z

B. −x − y + z

C. x − y − z

D. x − y + z

The standard enthalpy of formation of N₂H₄(l) is +50.6 kJ$$mol⁻¹. Calculate the enthalpy of vaporization, ΔH_vap, of hydrazine in kJ$$mol⁻¹.

N₂H₄(l) → N₂H₄(g)

(If you did not get an answer to (f), use −85 kJ but this is not the correct answer.)

Which equation shows the enthalpy of formation, $∆H_{\mathrm{f}}$, of ethanol?

A.  $2\mathrm{C} \left(\mathrm{s}\right)+3{\mathrm{H}}_2 \left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2 \left(\mathrm{g}\right)\to {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH} \left(\mathrm{g}\right)$

B.  $4\mathrm{C} \left(\mathrm{s}\right)+6{\mathrm{H}}_2 \left(\mathrm{g}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right)\to 2{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH} \left(\mathrm{g}\right)$

C.  $2\mathrm{C} \left(\mathrm{s}\right)+3{\mathrm{H}}_2 \left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2 \left(\mathrm{g}\right)\to {\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH} \left(\mathrm{l}\right)$

D.  $4\mathrm{C} \left(\mathrm{s}\right)+6{\mathrm{H}}_2 \left(\mathrm{g}\right)+{\mathrm{O}}_2 \left(\mathrm{g}\right)\to 2{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH} \left(\mathrm{l}\right)$

Calculate the standard enthalpy change for this reaction using the following data.

Determine the standard enthalpy change, ΔH^Θ, of step 1.

Why is the value of the enthalpy change of this reaction calculated from bond enthalpy data less accurate than that calculated from standard enthalpies of formation?

2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(g)

A.     All the reactants and products are gases.

B.     Bond enthalpy data are average values for many compounds.

C.     Elements do not have standard enthalpy of formation.

D.     Standard enthalpies of formation are per mole.

Determine the enthalpy change, ΔH, in kJ, for this reaction using data from the table and section 12 of the data booklet.

Determine the value of ΔH^Θ, in kJ, for the reaction using the values in the table.

Outline why no value is listed for H₂(g).

Consider the following reactions:

Fe₂O₃ (s) + CO (g) → 2FeO (s) + CO₂ (g)       ΔH^Θ = −3 kJ

Fe (s) + CO₂ (g) → FeO (s) + CO (g)               ΔH^Θ = +11 kJ

What is the ΔH^Θ value, in kJ, for the following reaction?

Fe₂O₃ (s) + 3CO (g) → 2Fe (s) + 3CO₂ (g)

A.   −25

B.   −14

C.   +8

D.   +19

What is the enthalpy change of the reaction?

C₆H₁₄ (l) → C₂H₄ (g) + C₄H₁₀ (g)

A.  + 1411 + 2878 + 4163

B.  + 1411 − 2878 − 4163

C.  + 1411 + 2878 − 4163

D.  − 1411 − 2878 + 4163

Determine the enthalpy change, ΔH, in kJ, for this reaction using data from the table and section 12 of the data booklet.

What is the enthalpy change of combustion of urea, (NH₂)₂CO, in kJ mol⁻¹?

2(NH₂)₂CO(s) + 3O₂(g) → 2CO₂(g) + 2N₂(g) + 4H₂O(l)

A.     2 × (−333) −2 × (−394) −4 × (−286)

B.     $\frac{1}{2}$[2 × (−394) + 4 × (−286) −2 × (−333)]

C.     2 × (−394) + 4 × (−286) −2 × (−333)

D.     $\frac{1}{2}$[2 × (−333) −2 × (−394) −4 × (−286)]

What is the enthalpy of combustion of butane in kJ mol⁻¹?

2C₄H₁₀(g) + 13O₂(g) → 8CO₂(g) + 10H₂O(l)

A.     4x + 5y − z 

B.     4x + 5y + z 

C.     8x + 10y − 2z 

D.     8x + 5y + 2z

Copper(II) chloride is used as a catalyst in the production of chlorine from hydrogen chloride.

4HCl (g) + O₂ (g) → 2Cl₂ (g) + 2H₂O (g)

Calculate the standard enthalpy change, ΔH^θ, in kJ, for this reaction, using section 12 of the data booklet.

What is the enthalpy change of the reaction, in kJ?

2C (graphite) + O₂(g) → 2CO (g)

A.  −394 − 283

B.  2(−394) + 2(−283)

C.  −394 + 283

D.  2(−394) + 2(283)

Determine the standard enthalpy change, ΔH^Θ, for the following similar reaction, using ΔH_f values in section 12 of the data booklet.

3C₂H₂(g) → C₆H₆(l)

Determine the standard enthalpy change, ΔH^Θ, for the following similar reaction, using ΔH_f values in section 12 of the data booklet.

3C₂H₂(g) → C₆H₆(l)

Thermodynamic data for the decomposition of calcium carbonate is given.

Calculate the enthalpy change of reaction, ΔH, in kJ, for the decomposition of calcium carbonate.

Determine the value of ΔH^Θ, in kJ, for the reaction using the values in the table.

Calculate the enthalpy change of reaction, ΔH, in kJ, for the decomposition of calcium carbonate.

Copper(II) chloride is used as a catalyst in the production of chlorine from hydrogen chloride.

4HCl (g) + O₂ (g) → 2Cl₂ (g) + 2H₂O (g)

Calculate the standard enthalpy change, ΔH^θ, in kJ, for this reaction, using section 12 of the data booklet.

Consider the following equations.

2Al (s) + $\frac{3}{2}$O₂ (g) → Al₂O₃ (s)    ΔH^Ɵ = −1670 kJ
Mn (s) + O₂ (g) → MnO₂ (s)    ΔH^Ɵ = −520 kJ

What is the standard enthalpy change, in kJ, of the reaction below?

4Al (s) + 3MnO₂ (s) → 2Al₂O₃ (s) + 3Mn (s)

A. −1670 + 520

B. $\frac{3}{2}$(−1670) + 3(520)

C. 2(−1670) + 3(−520)

D. 2(−1670) + 3(520)

Calculate the enthalpy change, in kJ, for the spray reaction, using the data below.

Calculate the standard enthalpy change (ΔH^⦵) for the forward reaction in kJ mol⁻¹.

ΔH^⦵_f PCl₃(g) = −306.4 kJ mol⁻¹

ΔH^⦵_f PCl₅(g) = −398.9 kJ mol⁻¹

Which equation represents the standard enthalpy of formation of lithium oxide?

A.  4Li (s) + O₂(g) → 2Li₂O (s)

B.  2Li (s) + $\frac{1}{2}$O₂(g) → Li₂O (s)

C.  Li (s) + $\frac{1}{4}$O₂(g) → $\frac{1}{2}$Li₂O (s)

D.  Li (g) + $\frac{1}{4}$O₂(g) → $\frac{1}{2}$Li₂O (g)

Calculate the standard enthalpy change (ΔH^⦵) for the forward reaction in kJ mol⁻¹.

ΔH^⦵_f PCl₃(g) = −306.4 kJ mol⁻¹

ΔH^⦵_f PCl₅(g) = −398.9 kJ mol⁻¹