Verified Solution • 2025–26 Session moderate

QJEEM21Chfbb6: JEE Main 2021 Chemistry - Class 11 JEEM21Chfbb6 Solution: For water at 100 C and 1 bar, vap H vap U = _____________ 10 2…

For water at 100 ∘^\circ C and 1 bar,

Δ\Delta vap H −- Δ\Delta vap U = _____________ ×\times 102 J mol −- 1. (Round off to the Nearest Integer)

[Use : R = 8.31 J mol −- 1 K −- 1]

[Assume volume of H2O(l) is much smaller than volume of H2O(g). Assume H2O(g) treated as an ideal gas]

Step-by-Step Verified Solution

H2O(l) ⇌\rightleftharpoons H2O(v)

Δ\Delta H = Δ\Delta U + Δ\Delta ngRT

For 1 mole waters;

Δ\Delta ng = 1

∴\therefore Δ\Delta ngRT = 1 mol ×\times 8.31 J/mol-k ×\times 373 K

= 3099.63 J ≅\cong 31 ×\times 102 J

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