Dr. Palmer Graves, Instructor

Answers

1. Circle the member of each pair which has the higher value of entropy.

H₂O (s) at 0° C          H₂O (l) at 0°C
H2 (g) at 0.5 atm      H2 (g) at 2.5 atm
CH₃CH₃ (g)             CH₃OCH₃ (g)

2. Calculate the standard molar entropy change for the formation of gaseous propane C₃H₈ at 25°C.

3 C (graphite) + 4 H₂ (g)   ---->   C₃H₈ (g)

3. Use the table of Thermodynamic values below to solve the following problems.
 

Compound	*Hf°(kJ/mol)	S°(J/Kmol)	*Gf° (kJ/mol)
Al (s)			28.3
AlCl3 (s)	-704.2	110.7
C (graphite)		5.74
C2H5OH (l)	-277.7	160.7	-174.78
CO2 (g)	-393.5	213.7	-394.4
C3H8 (g)		269.9
Cl2 (g)			223.1
H2 (g)			130.7
H2O (l)	-285.8	69.9	-237.1
O2 (g)			205.1

 

a. Calculate the standard molar entropy change and free energy change for the reactions shown below:
 

i. 2 Al(s) + 3 Cl₂ (g) ------>   2 AlCl₃ (s)
 
 

ii. C₂H₅OH (l) + 3 O₂ (g) ------> 2 CO₂ (g) + 3 H₂O (l)

4. Calculate the equilibrium temperature for both of the above reactions.