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JEE Main 20202 SeptemberMorning Shift
Exam
JEE Main
Year
2020
Date
2 September
Shift
Morning Shift
Subject
Chemistry
Chapter
Thermodynamics (C)

JEE Main 2020 · 2 September · Morning Shift · Chemistry · Thermodynamics (C)

The internal energy change (in J ) when 90g of water undergoes...

The internal energy change (in JJ) when 90g90g of water undergoes complete evaporation at 100°C100 ° C is ..............

(Given : ΔHvap{\Delta H}_{vap} for water at 373K=41kJ/mol373K = 41kJ / mol, R=8.314JK−1mol−1R = 8 . 314{JK}^{- 1}{mol}^{- 1})

Correct answer

189494

Step-by-step solution

Number of moles of water =9018=5moles\dfrac{90}{18} = 5moles

\DeltaH=\DeltaU+ΔngRT\begin{array}{ll}\DeltaH = \DeltaU + \Delta{n}_{g}RT\end{array}

41000X5=\DeltaU+5×8.314×373\begin{array}{ll}41000X5 = \DeltaU + 5 \times 8 . 314 \times 373\end{array}

205000=\DeltaU+15505.61205000 = \DeltaU + 15505 . 61

\DeltaU=189494.39J=189494J\DeltaU = 189494 . 39J = 189494J

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