STANDARDChemistry-Thermochemistry
STANDARD Chemistry Enthalpy of Formation MCQ Question
Type: MCQ-numerical-Medium
rU° of combustion of CH₄(g) at certain temperature is −393 kJ mol⁻¹. The value of ΔfH° is
A
Zero
B
< ΔfU°
C
ΔfU°
D
equal to ΔfU°
Correct Answer
Option B
Detailed Explanation
The balanced equation for combustion of methane is CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l). Here, Δng = 1 − 3 = −2. rH° = ΔfU° + ΔngRT; ΔfH° = −393 − 2RT. Therefore, ΔfH° < ΔfU°.
Found an issue with this question?
Related Questions
More from Thermochemistry
The standard heat of formation, in kcal/mol of Ba²⁺ is: [Given: standard heat of formation of SO₄²⁻ ion (aq) = -216 kcal/mol, standard heat of crystal...
2025Chemistry
From the following bond energies: H – H bond energy: 431.37 kJ mol⁻¹ C = C bond energy: 606.10 kJ mol⁻¹ C – C bond energy: 336.49 kJ mol⁻¹ C – H bond ...
2009Chemistry
Bond dissociation enthalpy of H₂, Cl₂ and HCl are 434, 242 and 431 kJmol⁻¹ respectively. Enthalpy of formation of HCl is
2008Chemistry