19. Chemical Thermodynamics
Gibbs Free Energy
19. Chemical Thermodynamics Gibbs Free Energy
49PRACTICE PROBLEM
Ethylene (C2H4) reacts with chlorine (Cl2) to yield dichloroethane (C2H4Cl2):
C2H4(g) + Cl2(g) → C2H4Cl2(l)
Use the following ΔG°f values to calculate the ΔG° for this reaction and show that this reaction is spontaneous at 25.0 °C.
ΔG°f (C2H4) = 68.1 kJ/mol
ΔG°f (Cl2) = 0 kJ/mol
ΔG°f (C2H4Cl2) = −79.6 kJ/mol
Explain why this addition reaction is nonspontaneous at higher temperatures. Calculate the temperature where the spontaneity of the reaction changes from spontaneous to nonspontaneous.
Ethylene (C2H4) reacts with chlorine (Cl2) to yield dichloroethane (C2H4Cl2):
C2H4(g) + Cl2(g) → C2H4Cl2(l)
Use the following ΔG°f values to calculate the ΔG° for this reaction and show that this reaction is spontaneous at 25.0 °C.
ΔG°f (C2H4) = 68.1 kJ/mol
ΔG°f (Cl2) = 0 kJ/mol
ΔG°f (C2H4Cl2) = −79.6 kJ/mol
Explain why this addition reaction is nonspontaneous at higher temperatures. Calculate the temperature where the spontaneity of the reaction changes from spontaneous to nonspontaneous.