The hydrogenation of ethene gas under standard conditions (T = 298K) shows a decrease in disorder (ΔS* = -120.7 J/(mol m*K)) during an exothermic reaction (ΔH* = -136.9 kJ/mol).

C_2H_4 (g) + H_2 (g) > C_2H_6 (g)

a. Explain how you would have predicted the sign of ΔS* for this reaction.

b. Explain what is happening to the disorder of the surroundings.

c. Determine whether the reaction is spontaneous or nonspontaneous by calculating ΔG°.

d. How would the spontaneity of the reaction change with an increase in temperature? Explain.