The Haber's process of production of ammonia involves the equilibrium:
`N_(2)(g)+3H_(2)(g)hArr2NH_(2)(g)`
Assuming `DeltaH^(@)` and `DeltaS^(@)` for the reaction do not change with temperature, which of the statements is true?
`(DeltaH^(@)=-95kJ and DeltaS^(@)=-198JK^(-1))`

Options

A. Ammonia dissociates spontaneously below 500 K
B. Ammonia dissociates spontaneously above 500 K
C. Ammonia dissociates at all temperatures.
D. Ammonia does not dissociates at any temperatures.

Answer

B

Explanation

`DeltaG^(@) = DeltaH^(@) -TDeltaS^(@) =-95 xx 1000 - 500 xx (-190) = -95000 + 95000=0`
Upto T=500 K the synthesis of ammonia is spontaneous. After 500 K synthesis becomes non-spontaneous, ammonia will dissociate spontaneously.