Problem 1: Alcohols for use as biofuels can be produced from glucose that is obtained from starch and cellulose in plants. Use the information in the table below to determine the free-energy change. at 78°C, which is the boiling point of an ethanol-water azeotrope.
C6H12O6 (s) → 2 CH3CH2OH (l) + 2 CO2 (g)
|
Compound
|
ΔHfº (kJ/mol)
|
Sº [J/(mol × K)]
|
|
Glucose (s)
|
-1,274
|
212
|
|
Ethanol (l)
|
-278
|
161
|
|
Carbon dioxide (g)
|
-394
|
214
|
In kJ.
Note: Report your final answer to the correct number of significant figures and do not use scientific notation when reporting your answer!
Problem 2: For a given reaction, ΔH = +21.38 kJ/mol and ΔS = +45.5 J/K . mol. Above what temperature is the reaction is spontaneous?