A reaction is spontaneous if free energy change `DeltaG` , for the reaction is negative . The question arises, how we can explain, the spontaneous of reversible reaction taking the example of dissociation equilibrium `N_2O_4 hArr 2NO_2(g)` the variation of free energy with the fraction of `N_2O_4` dissociated under standard conditions is shown in the figure below.

When 2 moles of `NO_2` change into equilibrium mixture the value of `DeltaG^@` is

Options

A. `(5.40 +0.84)kJ`
B. `(5.40-0.84)kJ`
C. `(-5.40 -0.84)kJ`
D. `-5.40 kJ`

Answer

C

Explanation

When 2 moles of `NO_2` change into equilibrium mixture, free energy is lowered by (5.40+0.84) kJ =6.24.
`DeltaG=-6.24 kJ`