JEE Main 2020ChemistryThermodynamics (C)MediumNumerical

JEE Main 2020 — Thermodynamics (C) Question with Solution

JEE Main 2020 (02 Sep Shift 2)

Question

The heat of combustion of ethanol into carbon dioxides and water is -327 Kcal at constant pressure. The heat evolved (in cal) at constant volume at 27° C (if all gases behave ideally) is R=2 calmol-1K-1________

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Show full solutionCorrect answer: 326400
Correct answer
326400

Step-by-step explanation

C2H5OH(ℓ)+O2(g)⟶2O2(g)+3H2O(ℓ);ΔHC=-327Kcal
ΔHc=ΔUC+ΔngRT
-327×103=ΔUC+1×2×300
ΔUC=-326400 cal

So heat evolved as constant volume is 326400cal 

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About this question

This is a previous-year question from JEE Main 2020, covering the Thermodynamics (C) chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.