Verified Solution • 2025–26 Session moderate

QJEEM22Ch5010: JEE Main 2022 Chemistry - Class 11 JEEM22Ch5010 Solution: For complete combustion of methanol CH 3 OH(I) + O 2 (g) CO 2…

For complete combustion of methanol

CH3OH(I) + 32{3 \over 2} O2(g) →\to CO2(g) + 2H2O(I)

the amount of heat produced as measured by bomb calorimeter is 726 kJ mol −- 1 at 27 ∘^\circ C. The enthalpy of combustion for the reaction is −- x kJ mol −- 1, where x is ___________. (Nearest integer)

(Given : R = 8.3 JK −- 1 mol −- 1)

Step-by-Step Verified Solution

CH3OH(l)+32O2( g)→CO2( g)+2H2O(l)\mathrm{CH}_{3} \mathrm{OH}(\mathrm{l})+\frac{3}{2} \mathrm{O}_{2}(\mathrm{~g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}(\mathrm{l})

amp;ΔH=ΔU+ΔngRTamp;=−726 kJ+(−12)×8.3×300amp;≃−727 kJ mol−1\begin{aligned}&\Delta \mathrm{H}=\Delta \mathrm{U}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT} \\\\&=-726 \mathrm{~kJ}+\left(\frac{-1}{2}\right) \times 8.3 \times 300 \\\\&\simeq-727 \mathrm{~kJ} \mathrm{~mol}^{-1}\end{aligned}

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