8. Thermochemistry

Hess's Law

Multiple Choice
Calculate the∆Hrxnfor the following thermochemical equation:
When given the following:
Multiple Choice
Calculate the∆H_rxnfor
Given the following set of reactions:
Multiple Choice
Calculate the∆H_rxn for
Given the following reactions:
Multiple Choice
Find ΔH_rxn for the following reaction:
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
Open Question
Calculate the enthalpy of the reaction 4B(s) + 3O₂(g) → 2B₂O₃(s)
Open Question
Consider the combustion of liquid methanol ch3oh(l)
Open Question
Calculate the enthalpy of the reaction 4B(s) + 3O₂(g) → 2B₂O₃(s).
Open Question
Consider the reaction H2O(l) → H2O(g), ΔH =44.0 kJ what will ΔH be for the reaction if it is reversed?
Multiple Choice
Using Hess's Law, calculate ΔH for the reaction 2 S (s) + 3 O2 (g) → 2 SO3 (g) at 298 K given the following reactions and their enthalpy changes:1. S (s) + O2 (g) → SO2 (g) ΔH = -296.1 kJ2. 2 SO3 (g) → 2 SO2 (g) + O2 (g) ΔH = 198.2 kJ
Multiple Choice
Calculate ΔHrxn for the following reaction using Hess's Law: Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g). Given the following reactions and their ΔH values: 1) 2Fe(s) + 3/2O2(g) → Fe2O3(s), ΔH = -824.2 kJ; 2) CO(g) + 1/2O2(g) → CO2(g), ΔH = -282.7 kJ.
Multiple Choice
Calculate ΔH_rxn for the reaction: N2O (g) + NO2 (g) → 3 NO (g) using the following reactions and given ΔH values: 1) 2 NO (g) + O2 (g) → 2 NO2 (g), ΔH = -113.1 kJ; 2) N2 (g) + O2 (g) → 2 NO (g), ΔH = +182.6 kJ; 3) 2 N2O (g) → 2 N2 (g) + O2 (g), ΔH = -163.2 kJ.
Multiple Choice
Calculate ΔH⁰ for the process 1/2 N2(g) + 1/2 O2(g) → NO(g) using Hess's Law and the following reactions: 1. N2(g) + 3 H2(g) → 2 NH3(g) ΔH⁰ = -91.8 kJ 2. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) ΔH⁰ = -906.2 kJ 3. H2(g) + 1/2 O2(g) → H2O(g) ΔH⁰ = -241.8 kJ
Multiple Choice
Using Hess's Law, calculate the ΔH for the reaction: N2(g) + 2O2(g) ---> 2NO2(g) using the following data:1. 2 NH3(g) + 4 H2O(l) ---> 2 NO2(g) + 7 H2(g) ΔH = −142.4 kJ2. N2(g) + 3H2(g) ---> 2NH3(g) ΔH = −115 kJ3. H2O(l) ---> H2(g) + 1/2 O2(g) ΔH = −43.7 kJ
Multiple Choice
Determine the enthalpy of reaction for 2CH₄(g) → C₂H₂(g) + 2H₂(g) using the given equations and Hess's Law.
Multiple Choice
Using Hess's Law, calculate the enthalpy change for the reaction: 2 Cl(g) + O2(g) → 2 ClO2(g), given that a chlorine-oxygen bond in ClO2(g) has an enthalpy of 243 kJ/mol, an oxygen-oxygen bond has an enthalpy of 498 kJ/mol, and the standard enthalpy of formation of ClO2(g) is ΔH°f = 102.5 kJ/mol.