Verified Solution • 2025–26 Session moderate

QJEEM24Ch454b: JEE Main 2024 Chemistry - Class 11 JEEM24Ch454b Solution: The heat of combustion of solid benzoic acid at constant volume …

The heat of combustion of solid benzoic acid at constant volume is −321.30 kJ-321.30 \mathrm{~kJ} at 27∘C27^{\circ} \mathrm{C} . The heat of combustion at constant pressure is (−321.30−xR) kJ(-321.30-x \mathrm{R}) \mathrm{~kJ} , the value of xx is __________.

Step-by-Step Verified Solution

C6H5COOH(s)+152O2( g)⟶7CO2( g)+3H2O(I)\mathrm{C}_6 \mathrm{H}_5 \mathrm{COOH}(\mathrm{s})+\frac{15}{2} \mathrm{O}_2(\mathrm{~g}) \longrightarrow 7 \mathrm{CO}_2(\mathrm{~g})+3 \mathrm{H}_2 \mathrm{O}(\mathrm{I})

amp;ΔH=ΔU+Δn9RTamp;ΔH=−321.30−12R×300\begin{aligned}& \Delta \mathrm{H}=\Delta \mathrm{U}+\Delta \mathrm{n}_9 R T \\& \Delta \mathrm{H}=-321.30-\frac{1}{2} \mathrm{R} \times 300\end{aligned}

So, x=150x=150

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