The internal energy change when a system goes fromk state `A` to `B` is `40 kJ mol^(-1)`. If the system goes from `A` to `B` by a reversible path and returns to state `A` by an irreversible path, what would be the net change in internal energy?

Options

A. zero
B. `40 kJ`
C. `gt 40 kJ`
D. `lt 40 kJ`

Answer

A

Explanation

Internal energy is a state function. Thus,
`Delta U = U_(f) - U_(i)`
Since the system returns to its initial state, `U_(f) = U_(i)`. Hence, `Delta U = 0`
It does not matter what path is followed.