8. Thermochemistry

The oxidation of ammonia is illustrated by the following equation:

4 NH₃ (g) + 5 O₂ (g) → 4 NO (g) + 6 H₂O (g)

Calculate the enthalpy of reaction, ΔH_Rxn, based on the given standard heats of formation. 

Consider the following equation: 

2 ClF₃(g) + 2 NH₃(g) → 1 N₂(g) + 6 HF (g) + 6 Cl₂(g) ΔH_rxn = –1196 kJ

Determine the standard enthalpy of formation for chlorine trifluoride, ClF₃. 

N₂ + 2 O₂ → 2 NO₂
Based on the following data.
2 NO → N₂ + O₂    ΔH = −180 kJ
2 NO + O₂ → 2 NO₂    ΔH = −112 kJ

2 C₂H₂ (g) + 5 O₂ (g) → 4 CO₂ (g) + 2 H₂O (l)

Calculate the enthalpy of the reaction 2NO(g) + O₂(g) → 2NO₂(g) given the following reactions and enthalpies of formation: 12N₂(g) + O₂(g) → NO₂(g), δH^∘_a=33.2 kJ 12N₂(g) + 12O₂(g) → NO(g), δH^∘_b=90.2 kJ

What is the isobaric heat of combustion for ethane, C₂H₆(g), in kJ per mole of ethane at 298.15 k?

How much energy is required to decompose 765 g of PCl₃

What is the heat of combustion of ethane, C₂H₆, in kilojoules per mole of ethane? Enthalpy of formation values can be found in this list of thermodynamic properties.

Use standard enthalpies of formation to calculate δh∘rxn for the following reaction: 2 H₂S(g) + 3 O₂(g)→ 2 H₂O(l) + 2SO₂(g)

Calculate the enthalpy of the reaction 2NO(g) + O₂(g) → 2NO₂(g)

Use the molar bond enthalpy data in the table to estimate the value of 

δ𝐻°_rxn for the equation C₂H₄(g) + HBr(g) ⟶ C₅H₅Br(g)

Use standard enthalpies of formation to calculate δh∘rxn for the following reaction: Cao(s) + CO₂(g) → CaCO₃(s)

Calculate the enthalpy change for the reaction P₄O₆(s)+2 O₂(g) → P₄O₁₀(s)

Calculate the enthalpy of the reaction 2NO(g) + O₂(g) → 2NO₂(g) given the following reactions and enthalpies of formation: 1/2N₂(g) + O₂(g) → NO₂(g), ΔH^∘_a=33.2 kJ 1/2N₂(g) + 1/2O₂(g) → NO(g), ΔH^∘_b=90.2 kJ

Using the table below, estimate δh for the "water splitting reaction": H₂O(g) → H₂(g) + 12 O₂(g).

Which answer best describes the transfer of heat that occurs when 1.20 mol of H₂ reacts?

Which answer best describes the transfer of heat that occurs when 1.70 mol of H₂ reacts?

Which answer best describes the transfer of heat that occurs when 1.40 mol of H₂ reacts?

Given the following at 25°C, calculate ΔH_f for HCN(g) (in kJ/mol) at 25°C.

In many ways, hydrogen as a biofuel compares very favorably to ethanol and other fuels.

Which answer best describes the transfer of heat that occurs when 1.30 mol of H₂ reacts?

4 NH₃(g) + 5 O₂(g) → 4 NO(g) + 6 H₂O(g)

What is the change in enthalpy associated with the combustion of 530 g of methane (CH₄)?

The enthalpy of the reaction is –2,840 kJ. What is the heat of combustion, per mole, of glucose?

Burning methane in oxygen can produce three different carbon-containing products: soot (very fine particles of graphite), CO(𝑔), and CO₂(𝑔). (c) For which of the three potential products is the magnitude of ΔH the largest?

Propylene glycol, C3H8O2, is a viscous liquid used in the production of polyester resins. A 1.500-g sample of propylene glycol is combusted to CO2(𝑔) and H2O(𝑙) in a bomb calorimeter for which the total heat capacity is 6.355 kJ/°C. The temperature of the calorimeter increases from 22.45 to 28.10°C.

a. Write a balanced equation for the combustion of propylene glycol to CO2(𝑔) and H2O(𝑙).

b. How much heat is evolved during the combustion of the 1.500-g sample of propylene glycol?

c. Calculate the enthalpy change for the combustion of one mole of propylene glycol to CO2(𝑔) and H2O(𝑙).

d. What is the value of Δ𝐻𝑓° for propylene glycol?

The combustion of one mole of liquid ethanol, CH₃CH₂OH, produces 1367 kJ of heat.

a. Write a balanced chemical equation for the combustion of ethanol.

b. Calculate how much heat is produced when 235.0 g of ethanol are combusted.

The combustion of one mole of liquid octane, CH₃(CH₂)₆CH₃, produces 5470 kJ of heat.

a. Write a balanced chemical equation for the combustion of octane.

b. Calculate how much heat is produced if 1.000 gallon of octane is combusted. Octane has a density of 0.692 g/mL at 20°C.

Which of the following statements about enthalpy is or are true?

a. Because E, P, and V are state functions, H is a state function.

b. If a system changes its state under a constant external pressure, then Δ𝐻=𝑞.

c. Under constant-pressure conditions, if Δ𝐻=0, then ΔE must also equal zero.