top of page

Spontaneity Examples 

Consider the following reaction 

N2(g) + 3H2 (g) (↔) 2NH3 (g)

1) Suggest why this reaction is important for humanity

Can't assimilate Ntirogen unless it is in the form of Ammonia can't metabolise N2, and we rely on plants and bacteria to make NH3. HH3 is important for amino acids.

The absolute entropy values S, at 328 K for N2 (g), H2 (g) and NH3 are 192 , 131, and 193 kJ  mol-1 respectively.

 

Calculate delta G for the reaction at 238 K. State and explain whether the reaction is spontaneous.

 

REMEMBER THE EQUATION: delta G = delta H - T delta S

 

= 76.0 - 298 (-0.199)) = - 16.7 (kJ)

 

As the value of Delta G is negative; it is spontaneous.

 

 

 

bottom of page