JEE Mains · Chemistry · STD 11 - 5. Thermodynamics and thermochemistry
The heat of combustion of ethanol into carbon dioxides and water is \(-327\, kcal\) at constantpressure. The heat evolved (in cal) at constant volume and \(27^{\circ} C\) (if all gases behave ideally) is \(\left( R =2\, cal\, mol ^{-1}\, K ^{-1}\right)\)
- A \(326400\)
- B \(312400\)
- C \(322425\)
- D \(322500\)
Answer & Solution
Correct Answer
(A) \(326400\)
Step-by-step Solution
Detailed explanation
\(C _{2} H _{5} OH _{(\ell)}+3 O _{2( g )} \longrightarrow 2 CO _{2( g )}+3 H _{2} O _{(\ell)}\) \(\Delta n _{ g }=2-3=-1\) \(\Delta_{ C } H =\Delta_{ c } U +\left(\Delta n _{ g }\right) RT\) \(\Delta_{ c } H =\Delta_{ c } U - RT\) \(\Delta_{ c } U =\Delta_{ c } H + RT\)…
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