Calculate Gibbs free energy and determine the type of thermodynamic reaction.
N2(g) + 3H2(g) ←→ 2NH3(g) + 43 kcal/mol
 
 ΔS = -740 kcal/mol.k
 
 At 25°, determine the ΔG and describe spontaneity of the reaction and what type of thermodynamic reaction is shown.