(a) A sample of 1.0 mol of a monoatomic ideal gas is taken through a cyclic process of expansion and compression as shown in figure. What will be the value of `DeltaH` for the cycle as a whole?
(b) Which quantity out of `Delta_(r)G` and `Delta_(r)G^(Theta)` will be zero at equilibrium?

Explanation

(a) The net enthalpy change, `DeltaH` for a cyclic process is zero as enthalpy change is a state function, i.e., `DeltaH ("cycle") = 0`
(b) Gibbes energy for a reaction in which all reactants and products are in standard state `Delta_(r)G^(@)` related to the equilibrium constant of the reaction as follows.
`Delta_(r)G = Delta_(r)G^(@) + RT ln Q`
At equilibrium, `0= Delta_(r)G^(@) + RT ln R (therefore Delta_(r)G =0)` & `Q = k_(eq)`
or `Delta_(r)G^(@) = -RT ln R`
`Delta_(r)G^(@) =0` when R=1
For all other values of K, `Delta_(r)G^(@)` will be non-zero.