Which of the following are not state functions? (I) $q+W$ (II) $q$ (III) $W$ (IV) $H-T S$
Which of the following are not state functions?
(I) $q+W$
(II) $q$
(III) $W$
(IV) $H-T S$
(I) and (IV)
(II), (III) and (IV)
(I,) (II) and (III)
(II) and (III)
Solution
Key Idea : State function is the property of the system whose value depends only on the initial and final state of the system and is independent of the path.
$\because$ Internal energy $(\Delta E)=q+W$
It is a state function because it is independent of the path. It is an extensive property.
$\because$ Gibbs energy $(G)=H-T S$
It is also a state function because it is independent of the path. It is also an extensive property.
Heat $(q)$ and work $(W)$ are not state functions being path dependent.