19. Chemical Thermodynamics
Entropy Calculations
78PRACTICE PROBLEM
Ethanol can be prepared in several ways. It can be produced during alcohol fermentation (Reaction A). It is also produced commercially from ethylene (Reaction B). Calculate the ΔG°rxn (kJ•mol–1) of each reaction.
A. C6H12O6(s) → 2 C2H5OH(l) + 2 CO2(g)
B. C2H4(g) + H2O(g) → C2H5OH(l)
Determine which method requires less energy under standard conditions.
Substance ΔG°f (kJ/mol)
C6H12O6(s) –910.4
C2H4(g) 68.4
C2H5OH(l) –174.8
H2O(g) –228.6
CO2(g) –394.4
Ethanol can be prepared in several ways. It can be produced during alcohol fermentation (Reaction A). It is also produced commercially from ethylene (Reaction B). Calculate the ΔG°rxn (kJ•mol–1) of each reaction.
A. C6H12O6(s) → 2 C2H5OH(l) + 2 CO2(g)
B. C2H4(g) + H2O(g) → C2H5OH(l)
Determine which method requires less energy under standard conditions.
Substance ΔG°f (kJ/mol)
C6H12O6(s) –910.4
C2H4(g) 68.4
C2H5OH(l) –174.8
H2O(g) –228.6
CO2(g) –394.4