H2O(ℓ)⇌H2O(v)
ΔH=ΔU+ΔngRT
for 1 mole waters ; Δng=1
∴ΔngRT=1mol×8.31J/mol−k×373K
=3099.63J≅31×102J
JEE Main 2021 — Chemistry Physical Chemistry
For water at 100∘C and 1 bar,
ΔvapH−ΔvapU=¯×102Jmol−1
(Round off to the Nearest Integer)
[Use : R=8.31Jmol−1K−1]
[Assume volume of H2O(l) is much smaller than volume of H2O(g). Assume H2O(g) treated as an ideal gas]
Held on 27 Jul 2021 · Verified 6 Jul 2026.
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