What is the standard enthalpy of formation of liquid butyraldehyde,CH₃CH₂CH₂CHO(l) ?
CH₃CH₂CH₂CHO(l) +
O₂(g) → 4H₂O(l) + 4CO₂(g) ; ΔH° = -2471.8 kJ
Substance
ΔH°_f (kJ/mol)
CO₂(g)
-393.5
H₂O(l)
-285.8

Question

What is the standard enthalpy of formation of liquid butyraldehyde,CH₃CH₂CH₂CHO(l) ?
CH₃CH₂CH₂CHO(l) +

What is the standard enthalpy of formation of liquid butyraldehyde,CH<sub>3</sub>CH<sub>2</sub>CH<sub>2</sub>CHO(l) ? CH<sub>3</sub>CH<sub>2</sub>CH<sub>2</sub>CHO(l) + O<sub>2</sub>(g) → 4H<sub>2</sub>O(l) + 4CO<sub>2</sub>(g) ; ΔH° = -2471.8 kJ Substance ΔH°<sub>f</sub> (kJ/mol) CO<sub>2</sub>(g) -393.5 H<sub>2</sub>O(l) -285.8 A) -245.4 kJ/mol B) +245.4 kJ/mol C) -1792.5 kJ/mol D) -3151.1 kJ/mol E) +3151.1 kJ/mol

O₂(g) → 4H₂O(l) + 4CO₂(g) ; ΔH° = -2471.8 kJ
Substance
ΔH°_f (kJ/mol)
CO₂(g)
-393.5
H₂O(l)
-285.8

Quizplus · Accepted Answer

Using Hess's Law, we can calculate the standard enthalpy of formation of butyraldehyde, CH3CH2CH2CHO(l).
We know that the standard enthalpy of formation of CO2(g) is -393.5 kJ/mol, and the standard enthalpy of formation of H2O(l) is -285.8 kJ/mol. Therefore, the enthalpy change for the reaction, 4CO2(g) + 4H2(g) → 4H2O(l) + CH3CH2CH2CHO(l), is (-393.5 kJ/mol x 4) + (-285.8 kJ/mol x 4) = -3142.2 kJ/mol.
We also know the enthalpy change for the reaction, CH3CH2CH2CHO(l) + 11/2O2(g) → 4CO2(g) + 5H2O(l), which is -2471.8 kJ/mol.
Therefore, the standard enthalpy of formation of CH3CH2CH2CHO(l) can be calculated using the equation:
ΔH°f(CH3CH2CH2CHO(l)) = (-2471.8 kJ/mol - (-3142.2 kJ/mol))/1 mol = 670.4 kJ/mol
However, for this question, we need to use the following equation, which includes the standard enthalpies of formation of the substances involved in the reaction:
CH3CH2CH2CHO(l) + 11/2O2(g) → 4CO2(g) + 5H2O(l)
ΔH°rxn = ∑ΔH°f(products) - ∑ΔH°f(reactants)
-2471.8 kJ/mol = (4)(-393.5 kJ/mol) + (5)(-285.8 kJ/mol) + ΔH°f(CH3CH2CH2CHO(l))
-2471.8 kJ/mol = -1574.0 kJ/mol + (-1429.0 kJ/mol) + ΔH°f(CH3CH2CH2CHO(l))
ΔH°f(CH3CH2CH2CHO(l)) = -245.4 kJ/mol
Therefore, the standard enthalpy of formation of butyraldehyde, CH3CH2CH2CHO(l), is -245.4 kJ/mol.

What Is the Standard Enthalpy of Formation of Liquid Butyraldehyde,CH3CH2CH2CHO(l)

What Is the Standard Enthalpy of Formation of Liquid Butyraldehyde,CH₃CH₂CH₂CHO(l)