Multiple Choice
Given the reaction Pb (s) + CO2 (g) → PbO (s) + CO (g) with ΔH° = +131.4 kJ, and the standard enthalpies of formation ΔHf° of CO2(g) = -393.5 kJ/mol and CO(g) = -110.5 kJ/mol, what is the standard enthalpy of formation for PbO(s)?
8. Thermochemistry
Enthalpy of Formation
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Use standard enthalpies of formation to calculate ΔH°_rxn for the following reaction: C(s) + H₂O(g) → CO(g) + H₂(g). Given the standard enthalpies of formation: ΔH°_f [C(s)] = 0 kJ/mol, ΔH°_f [H₂O(g)] = -241.8 kJ/mol, ΔH°_f [CO(g)] = -110.5 kJ/mol, ΔH°_f [H₂(g)] = 0 kJ/mol.
A
-352.3 kJ/mol
B
131.3 kJ/mol
C
-131.3 kJ/mol
D
0 kJ/mol
Verified step by step guidance1
Identify the given standard enthalpies of formation for each substance involved in the reaction: ΔH°_f [C(s)] = 0 kJ/mol, ΔH°_f [H₂O(g)] = -241.8 kJ/mol, ΔH°_f [CO(g)] = -110.5 kJ/mol, ΔH°_f [H₂(g)] = 0 kJ/mol.
Recall the formula for calculating the standard enthalpy change of a reaction (ΔH°_rxn) using standard enthalpies of formation: ΔH°_rxn = ΣΔH°_f(products) - ΣΔH°_f(reactants).
Apply the formula to the given reaction: C(s) + H₂O(g) → CO(g) + H₂(g). Calculate the sum of the standard enthalpies of formation for the products: CO(g) and H₂(g).
Calculate the sum of the standard enthalpies of formation for the reactants: C(s) and H₂O(g).
Subtract the sum of the enthalpies of the reactants from the sum of the enthalpies of the products to find ΔH°_rxn: ΔH°_rxn = [ΔH°_f(CO(g)) + ΔH°_f(H₂(g))] - [ΔH°_f(C(s)) + ΔH°_f(H₂O(g))].
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