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Multiple Choice
Use standard enthalpies of formation to calculate ΔH⁰_rxn for the following reaction: N2O4(g) + 4H2(g) → N2(g) + 4H2O(g). Given the standard enthalpies of formation: ΔH⁰_f [N2O4(g)] = 9.16 kJ/mol, ΔH⁰_f [H2(g)] = 0 kJ/mol, ΔH⁰_f [N2(g)] = 0 kJ/mol, ΔH⁰_f [H2O(g)] = -241.8 kJ/mol.
A
967.2 kJ
B
483.6 kJ
C
-483.6 kJ
D
-967.2 kJ
Verified step by step guidance
1
Understand the concept of standard enthalpy of formation (ΔH⁰_f), which is the change in enthalpy when one mole of a compound is formed from its elements in their standard states.
Use the formula for calculating the standard enthalpy change of a reaction (ΔH⁰_rxn): ΔH⁰_rxn = ΣΔH⁰_f(products) - ΣΔH⁰_f(reactants).
Identify the standard enthalpies of formation for each compound involved in the reaction: ΔH⁰_f [N2O4(g)] = 9.16 kJ/mol, ΔH⁰_f [H2(g)] = 0 kJ/mol, ΔH⁰_f [N2(g)] = 0 kJ/mol, ΔH⁰_f [H2O(g)] = -241.8 kJ/mol.
Calculate the total enthalpy of formation for the products: N2(g) and 4H2O(g). Use the formula: ΣΔH⁰_f(products) = ΔH⁰_f[N2(g)] + 4 * ΔH⁰_f[H2O(g)].
Calculate the total enthalpy of formation for the reactants: N2O4(g) and 4H2(g). Use the formula: ΣΔH⁰_f(reactants) = ΔH⁰_f[N2O4(g)] + 4 * ΔH⁰_f[H2(g)].