Question

The magnitude of enthalpy changes for irreversible adiabatic expansion of a gas from `1 L` to `2 l` is `Delta H_(1)` and for reversible adiabatic expansion for the same expansion is `Delta H_(2)`. Then
A. `DeltaH_(1) gt DeltaH_(2)`
B. `DeltaH_(1) lt DeltaH_(2)`
C. `DeltaH_(1)=Delta H_(2)`, enthalpy being a state function `(Delta H_(1)=Delta H_(2))`
D. `Delta H_(1)=Delta E_(1) & Delta H_(2)=Delta E_(2)` where `Delta E_(1) & DeltaE_(2)` are magnitudes of change in internal energy of gas in these expansions respectively.

Answer 1

Correct Answer - B
`|W_(rev)| gt|W_(lrr)|rArrT_("final"(rev)) ltT_("final"(lrr)) " "rArr DeltaT_(rev) gt DeltaT_(lrr)`
`:. DeltaH prop Delta T rArr DeltaH_(rev) gt Delta H_(lrr)`