Question

The magnitudes of enthalpy changes for irreversible adiabatic expansion of a gas from 1L to 2L is $\Delta$H1 and for reversible adiabatic expansion for the same expansion is $\Delta$H2. Then

• A. $\Delta$H1>$\Delta$H2
• B. $\Delta$H1<$\Delta$H2
• C. $\Delta$H1 = $\Delta$H2, enthalpy being a state function ($\Delta$H1 = $\Delta$H2)
• D. $\Delta$H1 = $\Delta$E1&$\Delta$H2 = $\Delta$E2 where $\Delta$E1&$\Delta$E2 are magnitudes of change in internal energy of gas in these expansions respectively.

Answer 1

Answer: (B)

$\Delta$H1<$\Delta$H2

Answer 2

|Wrev| > |WIrr|

Tfinal(rev) < Tfinal(Irr)

$\Delta$Trev > $\Delta$TIrr

$\because$ $\Delta$H $\propto \Delta$T

$\Delta$Hrev > $\Delta$HIrr